Solution-Processed Organic-Inorganic Perovskite Thin · PDF fileSolution-Processed...

Solution-Processed Organic-Inorganic Perovskite Thin-Film Transistors

with High Carrier Mobilities

*T. Matsushima1)2)3), A. S. D. Sandanayaka1),3), C. Qin1),3), T. Fujihara4), and *C. Adachi1),2),3) 1) Organic Photonics and Electronics Research (OPERA), Kyushu Univ., 744 Motooka, Nishi, Fukuoka 819-0395,

Japan, 2)Center for International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu Univ., 744

Motooka, Nishi, Fukuoka 819-0395, Japan, 3)Japan Science and Technology Agency (JST), ERATO, Adachi

Molecular Exciton Engineering Project, 744 Motooka, Nishi, Fukuoka 819-0395, Japan, 4)Innovative Organic

Device R&D Laboratory, Institute of Systems, Information Technologies and Nanotechnologies (ISIT), Fukuoka

Industry-Academia Symphonicity (FiaS) 2-110, 4-1 Kyudaishinmachi, Nishi, Fukuoka 819-0388, Japan * [email protected] and [email protected]

Keywords: Organic-inorganic perovskite, Semiconductor, Transistor, Carrier mobility, Solution processing

While organic-inorganic perovskite materials are currently attracting considerable attention as an absorber for

highly efficient solar cells, we have focused our attention on utilizing perovskite materials as the semiconductor in

field-effect transistors because perovskites promise the processability and flexibility inherent to organic

semiconductors as well as the excellent carrier transport inherent to inorganic semiconductors. Several reports of

transistors with perovskite as the semiconductor already exist but their field-effect carrier mobilities are not

sufficient for practical applications. The source of low carrier mobilities in reported perovskite transistors is thought

to be low perovskite quality, high carrier trap density, and inefficient carrier injection. In addition to improving

carrier mobilities, large hysteresis in the output and transfer characteristics measured at room temperature is another

serious issue for perovskite transistors. Thus, the true performance of perovskite transistors remains unknown and

open to debate.

In this study, we demonstrate a record hole mobility of up to 15 cm2 V−1 s−1 at room temperature along with

negligible hysteresis and good bias stability in p-channel transistors with a spin-coated semiconductor of the

perovskite (C6H5C2H4NH3)2SnI4 by solving the aforementioned issues through surface treatment of the substrate

with a self-assembled monolayer containing ammonium iodide terminal groups in combination with the adoption of

a top-contact/top-gate structure with MoOx hole injection layers [Fig. 1(a)] [1]. We also demonstrate the first-ever

n-channel operation in (C6H5C2H4NH3)2SnI4 transistors with a record electron mobility of up to 2.1 cm2 V−1 s−1 at

room temperature by combining low-work-function Al source/drain electrodes and C60 electron injection layers with

the top-contact/top gate structure [Fig. 1(b)] [2]. However, the presence of the contact resistance between the

(C6H5C2H4NH3)2SnI4 semiconductor and the source/drain electrodes is still problematic for both p- and n-channel

transistors. Although smaller channel lengths are crucial for the fabrication of transistor integrated circuits, we

decide to increase channel lengths to reduce the contribution of the contact resistance relative to the total resistance

for a better understanding of the intrinsic carrier

mobilities in a spin-coated (C6H5C2H4NH3)2SnI4 film.

We show that the intrinsic hole and electron

mobilities obtained at large channel lengths > 400

μm, where the relative contribution of the contact

resistance is negligibly small, are 26 and 4.8 cm2 V−1

s−1, respectively, for a spin-coated

(C6H5C2H4NH3)2SnI4 film [3]. The large contact

resistance at short channel lengths, small perovskite

crystallites, and a non-stoichiometric composition in

a resulting perovskite film are the remaining issues,

which must be overcome to further develop

perovskite transistors. We are now investigating to

overcome the above issues in our laboratory with the

aim of realizing carrier mobilities > 100 cm2 V–1 s–1

in solution-processed perovskite transistors.

References 1) T. Matsushima, C. Adachi, et al., Adv. Mater., 28, 10275 (2016).

2) T. Matsushima, C. Adachi, et al., Appl. Phys. Lett., 109, 253301 (2016).

3) T. Matsushima, C. Adachi, et al., Appl. Phys. Express, 10, 024103 (2017).

Fig. 1. (a) p-channel and (b) n-channel transport

properties of perovskite transistors.

Solvent-Free Printed Electronics by Electrophotography

*M. Sakai, and K. Kudo

Department of Electrical and Electronic Engineering, Chiba University, Japan *[email protected]

Keywords: Organic Electronics, Printed Electronics, Flexible Electronics, C8-BTBT, Electrophotography

Recent years, various printing processes are extensively developed for the industrial production of flexible

electronics using high-throughput roll-to-roll schemes. Conventional printing processes inevitably use inks

including toxic organic solvents. Toxic solvents and their vapor evaporated during drying the ink have high

environmental impact and also result in additional industrial cost for solvent recovery and/or neutralization. For

example, volatile organic compound (VOC) problem around large city is not resolved for a long time1)

. VOC

problem is difficult to resolve because each VOC emission site is small plant, factory, printing office, or construction

site and so on, and is highly dispersed. The sum of the emission is not negligible for atmosphere around the city

because VOC causes photochemical smog. In this paper, we present novel solvent-free printing using direct

patterning of organic materials with subsequent thin film formation2,3,4)

for the continuous fabrication of flexible

organic devices, which is expected to be applicable to industrial roll-to-roll processes and provide high throughput

production.

We prepared two substrates. The first was a thin (thickness:12µm) hybrid polyimide film (POMIRAN N) with a

900 nm thick parylene-SR buffer layer and Au contact electrodes. This substrate film was called cover film. The

second substrate (base film) was also the POMIRAN N film with Au gate electrode and a 900 nm thick parylene-SR

gate insulating layer. A proper amount of dioctylbenzothienobenzothiophene (C8-BTBT)5)

toner was transferred onto

the base or cover film by electrostatic toner marking. Then the base film

was covered by the cover film and inserted into thermal laminator or

ultrasonic welder to make a thin film.

Figure 1(a) is optical micrograph of the mixture of C8-BTBT toner

and carrier particle. A diameter of C8-BTBT toner particle is

approximately 5 m. Carrier particle consists of ferrite material with

polymer coating, of which diameter is approximately 70 m and the role

is to make toner particles being charged by friction. A proper amount of

the mixed particle was mounted on the magnet surface. High alternating

electric field was applied between the magnet and Au electrode pattern

prepared on the POMIRAN N surface. Charged C8-BTBT toner particles

were transferred from the surface of the carrier particle to the Au

electrode to make a pattern of dispersed toner, as shown in Figure 1(b).

C8-BTBT toner particles are clearly distributed on the Au electrode

patterns from 30 m up to 9.1 m line/space. By using our organic

semiconductor toner, we have succeeded in patterning of the organic

semiconductor onto flexible film substrates, and made thin film of

organic semiconductor by thermal lamination or ultrasonic welding. We

have confirmed that the field effect transistor was stable during and after

10,000 times bending under the bending radius of 1 mm.

Acknowledgement

The authors thank Professor Takashi Kitamura for valuable advices.

The authors also thank Nippon Kayaku Co., Ltd. and Powdertech Co.,

Ltd. for devoted cooperation. Hybrid polyimide film (POMIRAN N)

were provided by courtesy of Arakawa Chemical Industries, Ltd. Organic semiconductor toner particle was

pulverized by courtesy of Nippon Pneumatic Mfg. Co., Ltd. This work was supported by a research grant from the

Murata Science Foundation. This work was also supported by A-STEP program of Japan Science and Technology

Agency, Japan.

References

1) Website of the Ministry of Economy, Trade and Industry; http://www.meti.go.jp/policy/voc/top/

2) A. Inoue et al., Phys. Status Solidi A 210, 1353 (2013).

3) M. Sakai et al., Phys. Status Solidi (RRL) 7, 1093 (2013).

4) T. Sasaki et al., Adv. Electron. Mater., 2, 1500221 (2016).

5) H. Ebata et al., J. Am. Chem. Soc. 129, 15732 (2007).

100 µm

(a)

(b)

100 µm

C8-BTBT toner(d 5 μm)

carrier particle(d 70 μm)

Figure 1 (a) Optical micrograph of the

mixture of C8-BTBT toner particle

and carrier particle. (b) C8-BTBT

toner particle distributed on the Au

electrode pattern.

Electronic Structures of Organic Films and Interfaces Studied by High-Sensitivity Photoemission Technique T. Sato1), J. Yamazaki1), K. Shimizu1), K. Ikegami1), A. Matsuzaki1), H. Kinjo1), Y. Tanaka1)2) and *H. Ishii1)2)3) 1)Graduate School of Science and Engineering, 2) Center for Frontier Science, 3)Molecular Chirality Research Center, Chiba University, Chiba-shi, Chiba, Japan *[email protected] Keywords: Organic Semiconductor, High-Sensitivity Photoemission Spectroscopy, Gap State, Density of States, Interface electronic structure

Organic electronic devices such as organic light-emitting diodes, organic transistors and organic solar cells have attracted much attention. To understand the device physics and improve the performance, the elucidation of bulk and interface electronic structures is indispensable. Various spectroscopic techniques such as UV photoemission spectroscopy (UPS), photoelectron yield spectroscopy (PYS)[1], and inverse photoemission spectroscopy(IPES) have developed as tools for device researchers. These techniques give the information on the electronic structures such as ionization energy and electron affinity to construct device energy diagram to discuss the performance. The importance of such techniques is still growing up. In this presentation, the following topics on electronic structure issue including our development of measurement methods will be presented. 1)Interface electronic structure “How the energy levels align at interface when two solids become contact?” is a key question to construct the

energy diagram of device. The group of prof. K. Seki intensively investigated this issue for organic/metal interfaces, and the vacuum levels shift model in which the vacuum levels of the two solids do not align at the interface [2]. Later, several models have been developed to understand the mechanism. Now the existence of weak density-of-states in HOMO-LUMO gap is considered to be the key to control the energy level alignment. Actually, the numerical way to estimate the alignment was also proposed recently [3]. The overview on this energy level alignment issue will be briefly presented. 2)Direct observation of density-of-states of polymers including gap states

By improving the sensitivity of UPS and PYS, we have succeeded to determine the absolute value of DOS of several polymers such as nylon-6,6 and PTB7. Our new technique, called “hν-dependent high-sensitivity UPS” enables to observe the density-of-states in the range from 1015 to 1022 cm-3eV-1[4]. Based on the observed DOS distribution of nylon-6.6, the origin of the tribo-electricity of the polymer will be discussed. Our finding demonstrates the existence of gap states which can work as charge reservoir to be charged [5]. Regarding PTB7, which is a good material for organic solar cell, as a function of photo-carrier density, the position of quasi-Fermi level was estimated from the observed DOS. The relation between the existence of gap states and device property will be discussed. 3) Electronic structures of OLED-related film and interfaces

High sensitivity measurement makes it possible to detect unusual shallow states above Fermi level for various OLED-related films and interfacse. The films with spontaneous orientation polarization often captures anions at the surface with positive polarization charge. High-sensitivity UPS can observe such anions and give us the information about LUMO state [6]. Even without such positive polarization charge, shallow states were observed for OLED host materials such as non-polar CBP and polar Bebq2. The observed shallow states can be ascribed to exciton states and trap states. In relation to inverted-OLED structure, the interface electronic structure of ITO/polyethyleneimine/Bebq2 will be also reported [7].

References : 1) H. Ishii et al, Chap. 8 (pp. 131 -155) in Electronic processes in organic electronics: Bridging nanostructure, electronic states and device properties, eds. by H. Ishii, K. Kudo, T. Nakayama, N. Ueno, Springer (2015). 2) H. Ishii, K. Sugiyama, E. Ito, and K. Seki, Adv. Mater., 11(1999)605. 3) M. Oehzelt, et al., Nat. Commun. 5 (2014) 4174. 4) T. Sato, H.Kinjo, J. Yamazaki and H. Ishii, Appl. Phys. Exp., 10, 011602 (2017). 5) T. Sato, K. R. Koswattage , Y. Nakayama and H. Ishii, Appl. Phys. Lett.,110, 111102 (2017). 6) H. Kinjo, H. Lim, T. Sato, Y. Noguchi, Y. Nakayama and H. Ishii et al, Appl. Phys. Express, 9, 021601(2016). 7) K. Shimizu, H. Fukagawa, K. Morii, H. Kinjo, T. Sato and H. Ishii, MRS Advances Published Online, 1–6 (2017).

Improved Ambipolar Carrier Transport and Emission Properties of

Fluorene-Type Polymer Light-Emitting Transistors

*H. Kajii1), and Y. Ohmori1) 1)Osaka University, Suita, Osaka, Japan *[email protected]

Keywords: Organic light-emitting transistors, Ambipolar carrier transport, Conjugated polymers, Oriented films

Organic light-emitting transistors (OLETs) are multifunctional devices that combine the light emission

property of an organic light-emitting diode with the switching property of a field-effect transistor in a single device

architecture. As the emission occurs in the channel between source/drain (S/D) electrodes, OLETs can be used as the

micro-light source by patterning of S/D electrodes. Fluorene-type polymers specifically have emerged as an

important class of conjugated polymers due to their efficient emission, relative high mobility, and high stability [1-5].

Top-gate-type devices with ITO S/D electrodes using fluorene-type polymers [e.g. poly(9,9-dioctylfluorene) (F8),

poly(9,9-dioctylfluorene-co-bithiophene) (F8T2), poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT)] exhibit

both ambipolar and light-emitting properties.[2-5] We have previously achieved full channel illumination in bilayer

polymer light-emitting transistors that incorporated two

types of fluorene polymers and that were fabricated by a

solution process[6,7]. As the mobility of crystalized film is

higher than that of amorphous film, the OLETs can be driven

at the high current density. Given the higher mobility, a

high-brightness emission should to be achievable in an

OLET based on crystalline polymer films. In this study, we

investigated improved ambipolar carrier transport and

emission properties of solution-processed OLETs utilizing

fluorene-type polymers.

Liquid-crystalline semiconducting polymers are

self-organized owing to both the reorientation of molecules

and the increase in the size of crystalline regions during

thermal annealing. The F8(||) device using an oriented F8

layer with the channel direction parallel to the polymer

orientation exhibits higher hole and electron mobilities of

approximately 10-2 cm2/Vs as shown in Fig. 1, and improved

EL intensity than that with the channel direction

perpendicular to the polymer chains orientation.

Donor–acceptor polymers induce intermolecular interactions

through increased molecular ordering resulting from the

self-assembly of polymer chains, and this effect has led to

high field-effect mobility in OLETs. The device with the

poly(9,9-dioctylfluorene-co-dithienyl-benzothiadiazole)

(F8TBT) film annealed at moderate temperature exhibits higher hole field-effect mobility of approximately 0.1

cm2/Vs than other fluorene-type polymers and red to near-infrared emission. The improved hole field-effect mobility

results in the increased emission intensity. We also demonstrate the improved characteristics of single-layer

polymeric light-emitting transistors including printed carbon nanotube electrodes and polarized surface emission in

heterostructure OLETs utilizing oriented fluorene-type polymer films.

References 1) Y. Ohmori, M. Uchida, K. Muro and K. Yoshino, Jpn. J. Appl. Phys., 30, L1941-L1943 (1991),

2) H. Kajii, K. Koiwai, Y. Hirose and Y. Ohmori, Org. Electron., 11, 509-513 (2010),

3) K. Koiwai, H. Kajii and Y. Ohmori, Synth. Met., 161, 2107-2112 (2011),

4) I. Ikezoe, H. Tanaka, K. Hiraoka, H. Kajii and Y. Ohmori, Org. Electron., 15, 105- (2014),

5) H. Tanaka, H. Kajii, and Y. Ohmori, Synth. Met., 203, 10-15 (2015),

6) H. Kajii, H.Tanaka, Y.Kusumoto, T. Ohtomo and Y. Ohmori, Org. Electron., 16, 26-33 (2015),

7) T. Ohtomo, K. Hashimoto, H. Tanaka, Y. Ohmori, M. Ozaki and H. Kajii, Org. Electron., 32, 213-219 (2016).

0 20 40 60 80 10010

-3

10-2

10-1

100

101

F8TBT(spin coat)

F8(||)

F8()

VD=100V

I D (

A)

VG (V)

Fig. 1. Transfer characteristics of F8 devices with oriented

films and F8TBT device.

[Abstract] Trap density-of-states at pentacene/gate insulator interface measured via the in-situ field-effect thermally-stimulated-current technique *M.-C. Jung1), T. Fujii2), K. Kudo2), and M. Nakamura1) 1)Graduate School of Materials and Science, Nara Institute of Science and Technology, Japan 2)Graduate School of Engineering, Chiba University, Japan *[email protected] Keywords: in-situ field-effect thermally-stimulated-current, organic OTFT, trap density-of-states at interface Trap states at organic/gate insulator interfaces in organic thin-film transistors (OTFTs) highly influence on the characteristics and stability of OTFTs.1) Density and depth of the trap states depend on the chemical composition of the insulator surface although it does not significantly change the field-effect mobility under high-carrier-density conditions.2) We have been quantitatively studying the density of interface trap states using an originally developed instrument for the in-situ field-effect thermally-stimulated-current (FE-TSC) technique which enables us to characterize the trap states without exposing the sample to the air. By this instrument, the density of trap states at pure pentacene/gate insulator (bare and bis(trimethylsilyl)amine (HMDS)-treated SiO2) interfaces has been estimated. The results indicated the existence of an isolated trap state at 70–100 meV above the highest-occupied-molecular-orbital edge of pentacene, of which energy was insensitive to the surface chemical structure of any gate materials. Electron traps at 500–600 meV below the lowest-unoccupied-molecular-orbital edge appeared only after the bare SiO2 interface was exposed to the air.

References: 1) S. Yogev, R. Matsubara, M. Nakamura, U. Zschieschang, H. Klauk, and Y. Rosenwaks, Phys. Rev. Lett. 110,

036803 (2013). 2) Matsubara, Y. Sakai, T. Nomura, M. Sakai, K. Kudo, Y. Majima, D. Knipp and M. Nakamura, J. Appl. Phys. 118,

175502 (2015).

1011

1012

1013

1014

1015

1016

1017

Den

sity

of s

tate

s (c

m-2

eV-1

)

0.200.150.100.050.00-0.05-0.10Energy from HOMO-band edge (eV)

from band-edge fluctuation measured with AFMP

Pentacene HOMO band

Pen/SiO2interface

Pen/HMDSinterface

from bandcalculation

Effect of Flexural Deformation on Electrical Conductance of Transparent

Indium Tin Oxide Thin Film

H.-I Lu and

*C.-K. Lin

Department of Mechanical Engineering, National Central University, Jhong-Li District, Tao-Yuan City, Taiwan *[email protected]

Keywords: flexural deformation, indium tin oxide thin film, electrical conductance

Flexible electronic devices have great potential for widely novel applications as they can conform to a desired

shape, or flex in its use. In a typical flexible electronic assembly, a highly transparent, conductive electrode is

needed for light transmitting, e.g. in organic light-emitting diode and organic photovoltaic device. In practical

applications of such flexible electronic devices, they might be subjected to long-term static flexural deformation

which may cause damages in their components and degrade their performance. In particular, flexural-deformation

induced damages (microcracking and/or delamination) would reduce the electrical conductance of transparent,

conductive thin-film electrode. In this regard, structural reliability is one of the greatest challenges which must be

addressed prior to wide spread commercial application of flexible organic devices. For this reason, it is necessary to

investigate the bending behavior of transparent conductive thin film and how their electrical properties are affected,

when subjected to long-term static flexural deformation. The aim of this study is thus to systematically characterize

the effect of long-term static flexural deformation on the electrical conductance of transparent conductive thin film.

Flexural tests are conducted on indium tin oxide (ITO) thin film with a polymeric substrate, namely polyethylene

terephthalate (PET). The change of electrical resistance is monitored simultaneously during mechanical testing so as

to investigate the effect of flexural deformation on electrically conductive properties of the ITO film under bending.

In this study, a commercial ITO thin film on PET substrate (ITO/PET) sheet is used. Rectangular ITO/PET

samples in physical dimensions of 36, 51, 83, and 114 mm (length) x 10 mm (width) are cut out to conduct static

bending tests at various radii of curvature, namely 5, 10, 20, and 30 mm, respectively. For mechanical testing of ITO

thin film under static bending, each sample is firmly fixed in a homemade fixture with a specific bending curvature.

When the sample is bent in the fixture, ITO thin layer is under tension or compression if it is placed at the top or

bottom position, respectively. Each specimen is continuously bent until 1,000 h. During the bending test, electrical

resistance of ITO film is monitored using a source measurement unit. The resistance change of each ITO sample is

then determined in situ throughout the bending test. After mechanical test, facture surfaces of the ITO/PET

specimens are observed using an optical microscope and SEM to analyze the failure mechanism.

(a) (b)

Fig. 1 Relative change of electrical resistance in ITO/PET sheet under static bending at a curvature radius of (a) 10 mm and (b) 5 mm.

Results reveal that tensile bending is much more detrimental than compressive bending to the electrical

conductance of the given ITO/PET sheet under a long-term static flexural deformation. No significant change in

electrical resistance of the ITO/PET sheet is found for compressive bending after 1,000 h at a curvature radius of 10

mm or larger. For tensile bending at a curvature radius of 20 mm or larger, electrical conductance of ITO/PET sheet

is stable for up to 1,000 h. After 1,000 h of tensile bending at a 10-mm curvature radius, the electrical conductance

of ITO is degraded by 6%-20% (Fig. 1(a)). After tensile bending at a 5-mm curvature radius for 1,000 h, the amount

of change in electric resistance of ITO is about 600 times the initial electrical resistance value (Fig. 1(b)).

Fractography analyses reveal microcracks are formed to deteriorate the ITO/PET sheet’s electrical performance.

High Performance Flexible Transparent Heater with Super Water-repellency

Exhibited by PEDOT:PSS/Polymer Composite Nanoparticles

*S. Shiratori, T. Matsubayashi, M.Tenjimbayashi 1)Graduate school of Science and Technology, Keio University, Yokohama, Kanagawa, Japan, *[email protected]

Keywords: Transparent heater, power efficiency, de-icing, flexible electrode, water repellency

Ice formation causes numerous problems in many industrial fields as well as in our daily life. Various functional

anti-ice coatings have been extensively studied during the past several decades; however, the development of feasible

ice-repellent surfaces with long-term stability has been found to be extremely difficult.

In this study, an efficient anti-icing coatings have been developed by combining water-repellent and

electrothermogenic properties of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) embedded in ethyl

cyanoacrylate. The resulting film surfaces were able to effectively repel supercooled water droplets due to their strong

hydrophobicity and to serve as protective coatings against freezing rain. Moreover, the produced films possessed

important defrosting properties, which were related to the ability to generate heat via applied voltage, and thus could

be operational in freezing environments. The fabricated superhydrophobic heaters exhibited fast and uniform heating

responses as well as low energy consumption (260.8 °C cm2/W). In addition to the dewetting and defrosting properties,

the produced coatings were characterized by high mechanical and chemical resistance, good flexibility, and high

optical transparency. The proposed integrated fabrication method resulted in better film mechanical durability and

transparency as compared to the structures containing separate electrical conductive and hydrophobic layers.

Therefore, the synthesized transparent, conducting, and super-repellent nanocomposites can be potentially used in

anti-icing coatings, transmission antennas, wind rotor impellers, and other applications utilized in our daily life.

Furthermore, the described concept of integrated transparency, super-repellency, and electrothermal heating may

provide new insights into the design and development of the next-generation anti-icing coatings.

Figures. Heating characteristics of the conductive superhydrophobic surfaces. (a) A schematic of the superhydrophobic heater

with dimensions of 15 × 25 mm2. (b) Temperature profiles recorded for the P30 heater at applied voltages of 3, 6, 9, 12, 15, and 18

V. (c) Saturation temperatures for the superhydrophobic heaters with different PEDOT:PSS fractions. (d) A power consumption

plot for the P30 heater characterized by a high energy efficiency of 260.8 °C cm2/W. (e) Repeated heating/cooling cycles applied

to the superhydrophobic film heater. (f) Infrared images obtained for the superhydrophobic film heater before and after applying

voltage, which exhibit temperature uniformity across the entire heater surface.

Reference:Takeshi Matsubayashi, Mizuki Tenjimbayashi, Kengo Manabe, Masatsugu Komine, Walter Navarrini, and

Seimei Shiratori, ACS Appl. Mater. Interfaces 2016, 8, 24212−24220.

Giant Seebeck Effect in p-Conjugated Molecular Solids Enabling Thermoelectric Generators to be Revolutionary Simple *M. Nakamura1), H. Kojima1), and T. J. Inagaki2) 1) Nara Institute of Science and Technology, Ikoma, Nara, Japan, 2) Butsuryo College of Osaka * [email protected] Keywords: thermoelectric generator, organic semiconductor, giant Seebeck effect, charge-vibration coupling

In recent years, great attention has been placed on the "Internet of Things (IoT)" technologies. Wireless sensors are key devices to connect billions of “things” to the Internet world. So, can we maintain the billions of batteries for those sensors? A good solution is to use waste heat from our body or living environment to harvest electrical power. Development of flexible thermoelectric generators (TEGs) is therefore urgently necessary and studies on organic-based thermoelectric materials have become more and more intensive. In this talk, I will briefly introduce one of the on-going studies on organic-based thermoelectric materials in my group, the Giant Seebeck Effect (GSE).

The GSE was first found with pure C60 thin-films1) and eventually confirmed its universality in various organic semiconductors. Fig. 1 summarizes the temperature dependence of Seebeck coefficient and conductivities in some of the organic semiconductors. Irregularly large Seebeck coefficients, > 0.1 V/K, are observed for almost all materials. The Seebeck coefficient is sensitive to temperature as indicated by the connected marks, which is an irregular behavior for Seebeck effect in this temperature range. From a scientific point of view, the GSE is interesting because the conventional models in condensed matter physics cannot explain their extremely large Seebeck coefficients. A strong charge-vibration coupling in molecular solids is considered to be a driving force of this phenomenon (Fig. 2) and theoretical study is under progress. From an application point of view, such a large Seebeck coefficient possibly produces revolutionary simple TEGs (Fig. 3) being free from the series connection of hundreds of p- and n-type blocks. References 1) H. Kojima, R. Abe, M. Ito, Y. Tomatsu, F. Fujiwara, R. Matsubara, N. Yoshimoto, and M. Nakamura, Appl. Phys. Express 8, 121301 (2015).

Fig. 1. Temperature dependences of Seebeck coefficient and electrical conductivity in various organic semiconductors.

Fig. 2. Conceptual scheme of the Giant Seebeck Effect.

Fig. 3. Revolutionary simple structure of TEG.

Plasmonic-Gold Quantum Dots Hybrid Nanostructures for Improvement of

Organic Solar Cells

*A. Baba, C. Lertvachirapaiboon, K. Shinbo, K. Kato, F. Kaneko Graduate School of Science and Technology and Center for Transdisciplinary Research,

Niigata University, Niigata, Japan *[email protected]

Keywords: Plasmon, Gold quantum dots, Organic solar cells, Gold nanoparticles, Grating

Plasmonic photoelectric conversion systems are a promising approach to create additional light trapping for the

improvement of light absorption capability and efficiency of the solar cells without increase of the active layer

thickness [1-4]. When the gold particle size becomes smaller than 100 nm, localized plasmons are excited around

the gold nanoparticles by an irradiation of visible light. When the size of gold nanoparticles further becomes smaller

(< 2 nm), they are called gold clusters or gold quantum dots. As they have a diameter of less than 2 nm, they exhibit

a quantum size effect; this effect means that the size of the AuQDs determines the wavelength of the fluorescence

emission. Electrons in AuQDs are excited from the ground state to the excited state by absorbing mainly near-UV

light. This implies that AuQDs can harvest light from the UV region and convert it into visible light. Because most

organic photoelectric-converting materials harvest light mostly

in the visible range, one important challenge is to apply AuQDs

especially for organic light-harvesting systems. In this report,

enhanced properties of organic thin-film solar cells (OSCs) by

incorporating gold quantum dots (AuQDs) with plasmonic

systems are demonstrated.

Three types of AuQDs with different fluorescence

emission wavelengths: blue (B-AuQDs); green (G-AuQDs); and

red (R-AuQDs) are used. The emission wavelengths depended

on the number of gold atoms within the AuQDs. UV–vis spectra,

atomic force microscope images, current density versus voltage

properties, and the impedance spectra of the fabricated devices

were measured for the three types of AuQDs. AuQDs and

AuNPs were included into a

poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)

(PEDOT:PSS) thin-film layer of organic thin-film solar cells

(OSCs). The power conversion efficiency of AuQDs-AuNPs

loaded OSCs was increased as compared to the reference cell.

The result indicates that incorporating AuQDs into OSCs

increases the short-circuit current. Furthermore, further increase

was obtained by the combination of AuQDs and AuNPs as

shown in Fig. 1.

References:

1) S. Nootchanat, A. Pangdam, R. Ishikawa, K. Wongravee, K. Shinbo, K. Kato, F. Kaneko, S. Ekgasit and A. Baba,

Nanoscale, DOI: 10.1039/C6NR09951C (2017)

2) K. Hara, C. Lertvachirapaiboon, R. Ishikawa, Y. Ohdaira, K. Shinbo, K. Kato, F. Kaneko and A. Baba, Phys.

Chem. Chem. Phys., 19, 2791-2796 (2017).

3) A Pangdam, S Nootchanat, R Ishikawa, K Shinbo, K Kato, F Kaneko, C. Thammacharoen, S. Ekgasit and A.

Baba, Phys. Chem. Chem. Phys., 18, 18500-18506 (2016).

4) A. Baba, N. Aoki, K. Shinbo, K. Kato and F. Kaneko, ACS Appl. Mater. Interfaces., 3, 2080-2084 (2011).

Fig. 1. A schematic of fabricated

AuQDs/plasmonic enhanced OSC and J-V curves of AuQDs-AuNPs incorporated OSCs

Abstract Guideline (Leave two lines for presentation number)

Novel Benzothiadiazole-fused Naphthalenediimides for High Performance

OFETs Benlin Hu

1),

*Martin Baumgarten

1)

1) Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

* [email protected]

Keywords: Strong acceptor, Benzothiadiazole, Naphthalenediimide, n-type organic semiconductor,

Thiadiazoloquinoxaline

The exploration of strong acceptors to develop excellently organic semiconductors with high carrier mobility and

excellent stability is an intensive research topic in the community of organic electronics. Naphthalenediimide (NDI),

benzothiadiazole (BT) and N-heteroacene (NHT) are the most frequently used electron-deficient units to design high

performance n-type and ambipolar organic semiconductors. Herein, strong acceptors, benzothiadiazole-fused

naphthalenediimides (BT-f-NDI), that combine naphthalenediimide (NDI), benzothiadiazole (BT) and

N-heteroacene (NHT) in the same molecule are firstly reported. A series of BT-f-NDIs were synthesized by the

condensation of tetrabromo-NDI and benzothiadiazole diamine. The strong acceptors with LUMO energy levels of

~4.5 eV were obtained. Organic field-effect transistors (OFETs) based on the BT-f-NDI were fabricated by solution

process, showing good n-chanel field-effect character of high electron mobility and stability under ambient

conditions. The structures of single crystals are characterized to explicate the high mobility of the BT-f-NDIs.

Scheme 1. The synthesis of BT-f-NDIs.

References:

1) U. H. F. Bunz, Acc. Chem. Res., 48, 1676-1686 (2015)

2) A Mateo-Alonso, Chem. Soc. Rev., 43, 6311-6324 (2014)

3) U. H. F. Bunz, J. U. Engelhart, B. D. L. and M. Schaffroth, Angew. Chem. In. Ed., 52, 3810-3821 (2013)

4) T. Takeda, J. Tsutsumi, T. Hasegawa, S. Noro, T. Nakamurac and T. Akutagawa, J. Mater. Chem. C, 3,

3016-3022 (2015)

5) S. Ito, Y. Tokimaru and K. Nozaki, Chem. Commun., 51, 221-224 (2015)

6) D. Sakamaki, D. Kumano, E. Yashima and S. Seki, Angew. Chem. In. Ed., 54, 5404-5407 (2015)

7) S.Kato, T. Furuya, M. Nitani, N. Hasebe, Y. Ie, Y. Aso, T. Yoshihara, S. Tobita1 and Y. Nakamura, Chem. Eur.

J., 21, 3115-3128 (2015)

8) D. Timea, H. Manuel, B. Martin, Org. Lett., 13, 1936-1939 (2011)

9) D. Timea, B. Dirk, B. Gunther, B. Martin, J.Am.Chem.Soc., 133, 13898–13901 (2011).

Solution-processable Conjugated Small Molecules Semiconductors for High

Performance Organic Field Effect Transistor Application

G.-Y. He1), D.-Y. Huang1), B.-C. Chang1), S.-H. Tung2), M.-C. Chen1), and *C.-L. Liu1) 1) National Central University, Taoyuan, Taiwan, 2) National Taiwan University, Taipei, Taiwan *[email protected]

Keywords: organic semiconductor, field effect transistor, solution-processing, mobility, device

Organic small molecular semiconductors have attracted much attention for their potential applications in organic

field effect transistors (OFETs) for memory devices, smart cards, radio frequency identification tags, electronic

papers, flexible displays and sensors. Among these, solution-processable small molecules with high performance

and ambient stability are of great interest due to their possibility of a low-cost solution process and high flexibility in

molecular design/modification for various OFETs applications. The molecular design of these semiconductors

include aromatic building blocks with good -conjugation for optimal charge transport and appropriate alkyl chain

substitution to enable processability. With regard to the conjugated heterocyclic aromatics, fused- and

oligo-thiophenes are extensively studied in OFETs due to their extensive conjugation, strong intermolecular S-S

interactions, highly coplanar cores, and higher ambient stabilities. In particular, fused thiophenes exhibit a planar

backbone structure and strong π-π stacking in the solid state, resulting in the enhancement of the neighboring

molecular orbital overlapping, and so enabling more efficient charge carrier transport. As a result, a variety of small

molecular and polymeric fused thiophene semiconductors have been reported. However, solution-processable fused

thiophenes remain relatively unexplored compared to other -conjugated systems. We are particularly interested in

small molecules, since the latter have a number of advantages over polymers, such as structural versatility, facile

synthesis, high purity, better reproducibility, and reliability without batch-to-batch variations. In my presentation,

two series of small molecules, p-type compounds with alkyl chain-substituted tetrathienoacene (TTAR) as the

central core and both ends capped with thiophene (DT-TTAR), thienothiophene (DTT-TTAR) and dithienothiphene

(DDTT-TTAR) and n-type dialkyl dithieno[3,2-b:2′,3′-d]thiophene -based dicyanomethylene end capped quinoids

(DTTQs), are synthesized and examined as solution-processable organic semiconductors for OFETs applications.

Alkyl chain substituents modifications and end group effect strongly direct the molecular packing and

intermolecular interactions of the organic semiconductors. The physical and electrochemical properties as well as

OFETs performance and thin film morphologies of these new small molecules semiconductors are systematically

studied. Using a solution-shearing method, DTTQ-11 exhibits n-channel transport with the highest mobility of up to

0.45 cm2V-1s-1 and current ON/OFF ratio (ION/IOFF) greater than 105 whereas the highest mobility of up to 0.81 cm2

V-1 s-1 is achieved using DDTT-TTAR film. These results indicate that OFETs semiconducting materials can be

modulated through successive changes in conjugation length/side chain substituent length and molecular interaction,

based on a combination of molecular design and solution-processing technique.

References 1) S. Vegiraju, G.-Y. He, C. Kim, P. Priyanka, Y.-J. Chiu, C.-W. Liu, C.-Y. Huang, J.-S. Ni, Y.-W. Wu, Z. Chen,

G.-H. Lee, S.-H. Tung, C.-L. Liu, M.-C. Chen, and A. Facchetti, Adv. Funct. Mater., in press (2017).

(DOI: 10.1002/adfm.201606761)

2) H.-W. Hsu, W.-C. Chang, S.-H. Tung, and C.-L. Liu, Appl. Mater. Interface, 3, 1500714 (2016).

Fig.2. P-type TTAR small molecules.

Fig.1. Solution-sheared n-type DTTQs small molecules.

-20 0 20 40 60 80 1000.0

5.0x10-3

1.0x10-2

1.5x10-2

2.0x10-2

2.5x10-2

Gate Voltage (V)

DTTRQ-3

DTTRQ-6

DTTRQ-11

DTTRQ-15

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

Dra

in C

urre

nt

1/2 (A

1/2)

Dra

in C

urr

en

t (A

)

Fig.2. Transfer characteristics of DTTQs OFETs.

Abnormal strong burn-in degradation in solution-processed organic

bulk-heterojunction solar cells

*N. Li1), C. J. Brabec1)2) 1) Institute of Materials for Electronics and Energy Technology (i-MEET), Friedrich-Alexander University

Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany. 2) Bavarian Center for Applied Energy Research

(ZAE Bayern), Immerwahrstrasse 2, 91058 Erlangen, Germany. *[email protected]

Keywords: BHJ polymer solar cells, solution processing, phase separation, burn-in degradation, spinodal demixing.

Tremendous progress has been made in the field of organic photovoltaics (OPV) in the last few years, and the

power conversion efficiencies of OPV devices were steadily improved to the 12% regime. To push the OPV

technology towards commercial applications, the reliability and stability of champion OPV devices have to be well

examined and understood. The performance of solution-processed organic solar cells (OSCs) is determined by the

delicate, optimized bulk-heterojunction (BHJ) microstructure, where the organic donor and acceptor are fine-mixed

in the nano-meter regime to facilitate exciton dissociation at the donor/acceptor interface.

In this contribution, we will examine the reliability and stability of BHJ microstructures for various

state-of-the-art solution-processed OSCs and explore their potential for large-scale mass production.1-3 An abnormal

strong burn-in degradation is observed for highly-efficient OSCs, which dramatically reduces the charge generation

in OSCs at room temperature and in the dark. This abnormal degradation is caused by spinodal demixing of the

donor and acceptor phases, and can be attributed to the inherently low miscibility of both materials.3 Even though

the BHJ microstructure can be kinetically tuned for achieving high-performance, the inherently low miscibility of

donor and acceptor leads to spontaneous phase separation in the solid state. Furthermore, strategies to design and

develop BHJ microstructures with promising functionality and stability will also be discussed in this contribution.4

References:

1) N. Li and C. J. Brabec, Energy Environ. Sci., 8, 2902-2909 (2015).

2) C. Zhang, A. Mumyatov, S. Langer, J. D. Perea, T. Kassar, J. Min, L. Ke, H. Chen, K. L. Gerasimov, D. V.

Anokhin, D. A. Ivanov, T. Ameri, A. Osvet, D. K. Susarova, T. Unruh, N. Li, P. Troshin, C. J. Brabec, Adv. Energy

Mater., doi: 10.1002/aenm.201601204 (2016).

3) N. Li, J. D. Perea, M. Richter, T. Heumueller, G. J. Matt, Y. Hou, N. S. Güldal, H. Chen, S. Chen, S. Langner, T.

Kassar, M. Berlinghof, T. Unruh, C. J. Brabec, Nat. Commun., accepted (2017).

4) J. D. Perea, S. Langner, M. Salvador, C. Zhang, J. Kontos, G. Jarvas, A. Dallos, N. Li, C. J. Brabec, in

preparation (2017).

Electrolyte Dependence of Strain in Polypyrrole Softactuators

*F. Hata, H. Takahashi, S. Uto, and K. Kaneto Department of Biomedical Engineering, Osaka Institute of Technology, Osaka, Japan *[email protected]

Keywords: softactuators, conducting polymer, polypyrrole, electrochemomechanical deformation, ion radius

Softactuators using electroactive polymers (EAP) are intensively studied to drive robots, since they are lightweight,

compact and easy control. Among EAP such as ionic polymer and metal composites (IPMC), dielectric elastomers,

polymer gels and conducting polymers,1) the conducting polymers are the most prospective candidate for the

softactuators, because of large strain and stress by the low voltage operation. The conducting polymer swells and

shrinks upon electrochemical oxidation and reduction, respectively, that is, electrochemomechanical strain (ECMS).

It has been known that the electrochemical strain depends on the bulkiness of anion, which was inserted during

oxidation in conducting polymers. However, it has not been clarified that the detailed dimension of anions in

conducting polymer, namely, size of ionic radius or Stokes radius.

In this talk, anion dependence of ECMS in polypyrrole (PPy) softactuators is

presented. PPy film was prepared by electro-polymerization of pyrrole. Typical

dimension of PPy film, length (l) x width (w) x thickness (d) were 10mm x 2.0mm

x 20μm, respectively. For the measurement of ECMS, the handmade apparatus

shown in Fig.1 was used. The film was hanged at the working electrode(WE) ①,

and the opposite site of film was fixed at moving part② in Fig.1. The change of

film length (l) was conveyed to a reflector③ through a rod④ and the position

of reflector was measured with a laser displacement sensor. The apparatus was

immersed in 1M NaCl, NaNO3, NaBr, NaBF4, or NaClO4 as for the electrolyte

solution.

Curves (a) and (b) in Fig.2 show ECMS and cyclic voltammogram (CV) of

polypyrrole film, respectively, at the scan rate of 2 mV/s in NaBr.

From the integration of current in the CV curve the electric charge

(Q) inserted in the film was estimated. The curves (c) in Fig.2 show

the ECMS versus charge. From the gradient of the curve, the

incremental volume due to the inserted anion is estimated. Namely,

the number of anion (n) inserted is estimated by n = Q/e, where e is

the electron charge. If the volume of single anion is named as v0, the

volume increase of film by inserted anions will be v = nv0 (m3),

namely, v = (l+l)(w+w)(d+d) – lwd, where lwand are

increment of length, width and thickness, respectively. Assuming

the isotropic expansion of film, 2) the incremental volume v ≒

3(lwd)l /l, and the estimated ion radius (r) are obtained as Eq.(1),

(pm) . (1)

Fig.3 shows the estimated ion radii obtained from the present

experiment in horizontal axis. The vertical axis is the published

ones3) of stokes radius, ionic radius and covalent radius. It is

reasonable to suppose that the ions accommodate in polypyrrole

film as they settle by ionic bonding with polarons or bipolarons

rather than solvated ion in electrolytes. And also anions in

oxidized polypyrrole stay as ionic bonding.

This work was supported by JSPS KAKENHI Grant Number

16K06280.

References 1) K. Kaneto, J. Physics: Conference Series, Vol.704, Issue 1 April (2016) 012004.

2) M. Onoda et.al. Organic Iontronics, Morikita Pub. Comp. (2016) p102.

3) Jacob N. Israelachvili. Intermolecular and Surface Forces, Second Edition, Asakura Pub. (1996) p53.

Fig.2 ECMS (a), CV (b) and (c) strain for inserted charge amount in PPy film,

Fig.1 Handmade apparatus for the measurement of ECMS in polypyrrole film

polymers

Fig.3 Relationship of anion radii between Stokes radius, ionic radius and the estimated radius in PPy film,

Silver Nanoprisms Enhanced Propagating Surface Plasmon Resonance on

Metallic Grating Structure Detected by Transmission Surface Plasmon

Resonance Imaging Technique

*C. Lertvachirapaiboon

1), A. Baba

1), S.Ekgasit

2), K.Shinbo

1), K.Kato

1), and F.Kaneko

1)

1) Graduate School of Science and Technology, Niigata University, Japan,

2) Sensor Research Unit, Department of

Chemistry, Faculty of Science, Chulalongkorn University, Thailand *[email protected]

Keywords: transmission surface plasmon resonance image, metallic grating, silver nanoprisms, biosensor

Transmission surface plasmon resonance (TSPR) is a phenomenon

involving an extraordinary transmission of light through plasmonic

metal-coated nanohole arrays and grating structures. The enhanced

electric field associated with TSPR is highly sensitive to the local

dielectric condition at the metal interface and can be observed by

conventional spectroscopy and imaging technique. Hence, TSPR

technique has been employed for several biosensor applications.

Recently, the localized surface plasmon resonance (LSPR) from

plasmonic nanoparticles was used to facilitate and tune the electric field

at the metal-grating/dielectric interface for signal enhancement of TSPR

substrates. We previously reported an enhancement of a TSPR signal by

plasmonic nanoparticles (e.g. silver and gold nanoparticles) and the

distance-dependent plasmon resonance coupling between a metal

grating film and functionalized metal nanoparticles. In this study, we

investigated the effect of near-field LSPR of silver nanoprisms

(AgNPrs) on the far-field TSPR of a silver-coated grating substrate and

exploited this hybrid material as a hydrogen peroxide (H2O2) sensor.

Silver-coated grating substrates were functionalized with

3-mercapto-1-propanesulfonic acid sodium salt before deposition of

a 5-bilayer poly(allylamine hydrochloride)/poly(sodium 4-styrene

sulfonate) (PAH/PSS). AgNPrs were subsequently deposited on

the functionalized surface to determine the enhancement of

TSPR phenomenon. The TSPR image and TSPR signal were

recorded using a camera coupled with liquid crystal tunable

filters. An obvious increase in TSPR intensity and a redshift of the TSPR

peak position were observed when AgNPrs were deposited onto the

functionalized silver grating substrate (Fig. 1A). These results indicated

that the plasmon excitation of TSPR could be facilitated and further

excited by LSPR of the AgNPrs. A darker TSPR image with the decrease in TSPR intensity at the wavelength of 720

nm from 2471.8 (black line in Fig 1B) to 1079.2 counts (red line in Fig. 1B) was detected by camera. The

decreasing in TSPR signal after deposition of AgNPrs was due to the shifting of TSPR peak to longer wavelength.

Due to the oxidative disintegration of AgNPrs via H2O2, this hybrid material was employed to use as a H2O2

sensor. The 3-channel microfluidic cell was assembled to the developed substrate. Water and aqueous solutions of

H2O2 at concentrations of 1 and 10 µM were simultaneously injected into the microfluidic channels for 10 min, and

water was subsequently injected into all channels. The ∆TSPR intensity of the silver grating with AgNPrs substrate

from the detected channels with 1 and 10 µM H2O2 and water were 290.3, 653.6, and 27.1 counts, respectively.

These promising results strongly indicated that the TSPR imaging technique can be exploited in biosensor

applications, particularly with an oxidative enzyme system (e.g. glucose oxidase, cholesterol oxidase, reduced

dihydronicotinamide adenine dinucleotide oxidase).

References 1) T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, Nature, 391, 667-669 (1998), 2) A. Baba, et al., Adv. Funct. Mater., 22, 4383-4388 (2012), 3) C. Lertvachirapaiboon, et al., Plasmonics, 9, 899-905 (2014), 4) T. Parnklang, et al., RSC Adv., 3, 12886-12894 (2013).

Fig. 1. (A) TSPR spectra and (B) corresponding

TSPR images and TSPR intensities of silver

grating substrate with (red line) and without

AgNPrs (black line).

without AgNPrs

with AgNPrs

with AgNPrs

without AgNPrs

1000 1200 1400

Co

un

ts

Pixel

500

TS

PR

inte

nsity

A

700 720 740 760

TS

PR

inte

nsity

Wavelength (nm)

400 500 600 700 800 900

Wavelength (nm)

B

Structure of a Model Dye/Titania Interface: Geometry of Benzoate on Rutile-TiO2 (110)(1x1) W. Busayaporn1),2),3), D. A. Duncan4), F. Allegretti4), A. Wander2), M. Bech5), P. J. Møller5)†, B. P. Doyle6), N. M. Harrison2),7), G. Thornton8), *R. Lindsay1)

1)Corrosion and Protection Centre, School of Materials, The University of Manchester, Sackville Street, Manchester, M13 9PL, UK, 2)STFC, Daresbury Laboratory, Daresbury, Warrington WA4 4AD, UK, 3)Synchrotron Light Research Institute, Nakhon Ratchasima 30000, Thailand, 4)Physik-Department E20, Technische Universität München, James-Franck Str. 1, D-85748 Garching, Germany, 5)Department of Chemistry, University of Copenhagen, Universtetsparken 5, DK 2100 Copenhagen Ø, Denmark, 6)TASC-INFM Laboratory, Area Science Park – Basovizza, Trieste I-34014, Italy, 7)Department of Chemistry, Imperial College London, Exhibition Road, London SW7, 8)London Centre for Nanotechnology and Chemistry Department, University College London, 20 Gordon Street, London WC1H 0AJ, UK *[email protected] Keywords: Titania, Chemisorption, Surface structure, Titanium oxide, Carboxylic acid, Single crystal surface, Photoelectron Diffraction

Scanned-energy mode photoelectron diffraction (PhD) and ab initio density functional theory (DFT) calculations have been employed to investigate the adsorption geometry of benzoate ([C6H5COO]-) on rutile-TiO2(110)(1x1) (1). PhD data indicate that the benzoate moiety binds to the surface through both of its oxygen atoms to two adjacent five-fold surface titanium atoms in an essentially upright geometry. Moreover, its phenyl (C6H5-) and carboxylate ([-COO]-) groups are determined to becoplanar, being aligned along the [001] azimuth. This experimental result is consistent with the benzoate geometry emerging from DFT calculations conducted for laterally rather well separated adsorbates. However, at shorter inter-adsorbate distances, the theoretical modeling predicts a more tilted and twisted adsorption geometry, where the phenyl and carboxylate groups are no longer coplanar, i.e. inter-adsorbate interactions influence the configuration of adsorbed benzoate. The result from calculation also disputed the previous work proposed on alternatively twist model of phenyl ring on the rutile-TiO2

(110)(1x1) surface (2). References (1) W. Busayaporn, D. A. Duncan, F. Allegretti, A. Wander, M. Bech, P. J. Møller, B. P. Doyle, N. M. Harrison, G. Thornton, R. Lindsay, J. Phys. Chem. C, 120 (27), 14690–14698 (2016). (2) Q. Guo, I. Cocks, E. M. Williams, Surf. Sci., 393, 1 (1997). † Deceased

Fig. 1 Theoretical modeling predicts a more tilted and twisted adsorption

geometry of phenyl (C6H5-) ring on rutile-TiO2

(110)(1x1) surface.

Relationship between Elasticity and Contraction Force in Conducting

Polymer Polyaniline Softactuators *K. Kaneto, H. Takahashi, F. Hata, and S. Uto

Department of Biomedical Engineering, Osaka Institute of Technology, Osaka, Japan *keiichi,kaneto@oit. ac. jp

Keywords : conducting polymer, artificial muscle, softactuator, Young’s Modulus, contraction force

Artificial muscles or softactuators are interested in the application to human friendly robots with noiseless and

simple structure for complicated motions. Amongst several materials in softactuators, conducting polymers are

superior in operation voltage, magnitude of deformation and contraction force, as well as electrical conductivity,

flexibility and toughness, being suitable for softactuator. They are electrochemically oxidized and reduced in

electrolyte solution, resulting in the electrochemomechanical deformation (ECMD). The ECMD of conducting

polymer is induced by insertion and exclusion of anions. It has been shown that the magnitude of deformation is

determined by the total volume of inserted bulky ions, being up to 40%1)

at the most and larger than skeletal muscle

of 25%. The contraction force is several MPa, being ten times larger than that of muscle of 0.4 MPa. However, little

is known about the origin of contraction force. In this talk, the contraction force is discussed based on the

experimental results on static stress-strain -) and ECMD measurements under tensile loads in polyaniline films.

Polyaniline was synthesized by chemical oxidation from aniline in hydrochloric acid. The polyaniline

(emeraldine base; EB) powder was dissolved in NMP and casted on a slid glass, resulting in EB film with the

thickness of 20~25 m. The EB film was cut in strips with the dimension of 15mmx2mm, and used for the

measurements. Electrical conductivity（el）was measured by 4 probes methods.

Curves in Fig.1 show typical -characteristics for EB and ES films immersed in various acids of 1M HCl, HBr,

HBF4 and HClO4, H2SO4 (exceptionally 0.1M). The -measurements were carried out with several films and the

data were averaged. From the gradient of linear approximation of curves the Young’s moduli were obtained from

= Y. Figure 2 shows typical strain (l/l0) of ECMD under tensile loads (f), which were applied to ES films in the

acid electrolytes. The linear approximation of the curves shown in Fig.2 gives an empirical relationship of l/l0 = -

f/E + lm/l0, where E is quasi-Young’s modulus during electrochemical reaction. lm/l0 is the maximum strain or

deformation at zero tensile loads. E is obtained from the reciprocal gradient of the curves. In Table 1 summarized

the parameters of conductivities, Young’s Moduli, E and the maximum ECMD and blocking force ( f0 ), which is

obtained from the relationship of l/l0 = 0.

It is interesting to note that ES films of HBF4 and HClO4

show low electrical conductivity and high Young’s modulus

Y and E values compared with others as shown in Table 1.

The results indicates that ES films doped with the large

anion are somehow hard, less conductive, lager blocking

force and smaller deformation. However, this is not

conclusive at the present stage. It is also noted that H2SO4 is

di-anion, which may bond with two polarons or bipolaron,

and form ionic crosslink, though the Y is unexpectedly small.

This work was supported by JSPS KAKENHI Grant Number 16K06280.

1) S. Hara, T. Zama, W. Takashima and K. Kaneto, Smart. Mater. Struct. 14 (2005) 1501-1510.

Fig. 1. Typical results of static stress-strain curves in polyaniline EB and ES in various acids

Fig. 2. Characteristic of tensile load dependence of ECMD strain in polyaniline film.

Table 1. Parameters in ES in various acids, YEB=0.26 GPa

Colorimetric organic dosimeter to promote most efficient use of neonatal

phototherapy

*R.F. Bianchi1), G.R. Ferreira1)2) , A.M. Tannure1), M.F. Savedra1) and A.G.C. Bianchi 1) Universidade Federal de Ouro Preto, Ouro Preto – MG, Brazil, 2) Universidade dos Vales do Jequitinhonha e Mucuri, Janaúba – MG, Brazil *[email protected] Keywords: Radiation sensor, innovation, flexible device, medical device. Hyperbilirubinemia is a systemic global problem and an often diagnosed pathology in newborns. In most cases blue-light phototherapy (410-460 nm) is the only treatment required to prevent the bilirubin neurotoxicity, but its effectiveness is dose-dependent and it is highly affected by the skills, knowledge, and attention from nurses and clinicians who implement the treatment. This paper presents a novel light-sensitive colorimetric dosimeter to simulate the effect of blue-light phototherapy on the optical properties of in-vitro bilirubin. The dosimeter is based on a multilayered organic structure comprising a light-stable green light emitter (copper phthalocyanine, C32Cl16CuN8), and a blue-light sensitive red emitter (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene] vinylene, OC1OC6-PPV). The optical and chemical properties of the dosimeter were investigated by fluorescence and FTIR spectroscopies and by color coordinates of CIE (1931) diagram chromatics, while the photochemical process of bilirubin was evaluated by UV-Vis absorption spectroscopy. The optical response of the dosimeter for conventional (10 µW/cm2) and intensive (40 µW/cm2) phototherapy was found to present the same photochemical kinetics of bilirubin. These findings highlight a cutting-edge solution for monitoring the bilirubin elimination in neonates as a function of the dosimeter’s color evolution. This novel colorimetric dosimeter provides a standardized method for reporting and measuring phototherapy dose to promote an efficient use of available phototherapy units in health facilities.

FIG. 1: CIE 1931 obtained from fluorescence spectra obtained from dosimeters during (a) conventional and (b) intensive phototherapy units.

References 1) G.R. Ferreira, C.K.B. de Vasconcelos, R.F. Bianchi, Med. Phys 36, 642 (2009) 2) C.K.B. de Vasconcelos and R.F. Bianchi, Sens. Act. B: Ch,em, 30 (2009) 3) G.R. Ferreira, A.M. Tannure, M.F. Siqueira, A.G.C. Bianchi, R.F. Bianchi, Sens. Act. B: Chem 240, 1003 (2017)

Tuning solid-state fluorescence of co-crystal materials by regulating

the arrangement of pyrene fluorophores

Hao Sun, Mingliang Wang*

School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 211189,

People’s Republic of China

*Corresponding author: E-mail: [email protected]; Fax: +86 2585092237; Tel: +86

13601401581

Keywords: pyrene; 17β-Estradiolum; binary-component co-crystal; modulation of fluorescence

emission

Abstract

One new binary-component co-crystal complexe (molar ratio 1:1) based on pyrene and

17β-Estradiolum was fabricated via molecular self-assembly and comprehensively characterized.

Co-crystal materials were prepared through both grinding and solvent evaporation method. Crystal

structural analysis revealed that fence-like stacking mode

was formed by H-bonds between the fore and aft end

hydroxys of 17β-Estradiolum. This space structure

effectively weakens the π···π interaction between the pyrene

chromophore and then induces the transformation of crystal

from dimer stacking mode towards oligomer stacking mode.

The variation of fluorescence emission caused by change of

stacking patterns indicates that altering π···π interactions can

realize the modulation of optical properties. This study

demonstrates that using a co-crystal strategy could provide unique stacking assembly, which may have

a high potential application in optoelectronic materials.

References:

1) Q. J. Shen, X. Pang, X. R. Zhao, H. Y. Gao, H. L. Sun and W. J. Jin, CrystEngComm, 14,

5024-5034(2012).

2) K. B. Landenberger and A. J. Matzger, Crystal Growth & Design, 10, 5341-5347(2010).

3) Z. J. Zhao, S. M. Chen, J. Lam, Z. M. Wang, P. Lu, F. Mahtab, H. Sung, I. D. Williams, Y. G.

Ma, H. S. Kwokc and B.Z. Tang, J Mater Chem, 21, 7210-7216(2011).

4) Feng, Q.; Wang, M. L.; Dong, B. L.; He, J.; Xu, C. X. Crystal Growth & Design, 13,

4418-4427(2013).

5) Dong, B. L.; Wang, M. L.; Xu, C. X.; Feng, Q.; Wang, Y. Crystal Growth & Design, 12,

5986-5993(2012).

Fig. 1. Fluorescence microscopy images of pyrene

and co-crystal (λex =365 nm).

Assessment of cell membrane damage via second harmonic generation

microscopy

*N. Kato, R. Kondo, and Y. Ohori

Department of Electronics and Bioinformatics, Meiji University, Kawasaki 214-8571, Japan. *[email protected]

Keywords: Second harmonic generation, Two-photon excited fluorescence, Cell viability, Cytotoxicity, HeLa cell

The materials that damage the cell membrane are cytotoxic and the cytotoxicity test can be made by assessing the

cell metabolic activity or detecting the membrane leakage. In this presentation, we offer the method to analyze

membrane damage via second harmonic generation (SHG), whose intensity is sensitive to the lipid order in the

membrane.1)

To make the cell membrane SHG active, the membrane was stained by the amphiphilic polar dye

molecules (Fig. 1, RH237, Thermo Fisher Scientific Inc.). Because of the amphiphilic nature of RH237, the dyes

intercalate parallel to the lipids in the outer leaflet of the plasma membrane and align their polar axis in one direction,

resulting in the SHG-active membrane. The SHG intensity (ISHG) as well as the two-photon excited fluorescence

(TPF) intensity (ITPF) of the dyes were observed by the microscope. Since polycation damages the cell membrane,

poly(ethyleneimine) (PEI) was used as the model toxic agent [2].

Fig. 1. Molecular structure of dye used for staining cell membrane.

0 2 4 6 8

PEI Concentration (g/ml)

0

20

40

60

80

100

Cel

l V

aibil

ity

(%)

ISH

G / ITP

F

0

0.1

0.2

0.3

0.4

0.5

0.6

Here, we report the correlation between the cytotoxicity and ISHG. We observed the ISHG and ITPF of the stained

HeLa cells as a function of the PEI concentration in the culture medium. Fig. 2 shows the bright-felid and SHG

images of the HeLa cells. The cells incubated in the medium with PEI (Fig. 2(d)) exhibits lower ISHG than those

incubated without PEI (Fig. 2(b)), and as the concentration of PEI in the culture medium increases, the ISHG

decreases and ITPF increases. We assume that the ITPF is proportional to the number of dye molecules, and the value

of ISHG/ITPF was plotted as a function of the PEI concentration. The dependence of the cell viability (CV) on the PEI

concentration was also obtained by the conventional assay (CCK-8). As shown in Fig. 3, the ISHG/ITPF and the CV

show the same dependence on the PEI concentration. Because the decrease in the lipid order induced by the

membrane damage reduces the order of the dyes intercalated in the membrane, resulting in the decrease in the ISHG,

the cytotoxicity correlates to the lipid order in the membrane. Thus, the present result indicates that the proposed

method can be applied for the cytotoxicity test.

References:

1) D. Fischer, T. Bieber, Y. Li, H.-P. Elsässer, and T. Kissel, Pharm. Res. 16, (1999) 1273-1279.

2) L. Saccani, I. M. Tolic-Nørrelykke, M. D’Amico, F. Vanzi, M. Olivotto, R. Antolini, and F.S. Pavone, Cell

Biochem. Biophys. 45, (2006) 289-302.

Fig. 2. (a) and (b) bright-field and the SHG images of HeLa cells incubated in the medium without PEI, (c) and (d) those of the cells in the medium with PEI (7.5 μg/mL).

Fig. 3. ISHG/ITPF and cell viability as a function of PEI concentration in the culture medium.


Detection sensitivity of excited singlet oxygen molecule under vacuum

condition by using spin trap agent incorporated water-soluble polymer films

*K. Hosoya1), Y.Saranya1), Y. Tadokoro1), and S. Iwamori1) 1)Tokai University, 4-1-1, Hiratsuka, Kanagawa, Japan * [email protected]

Keywords: detection sensitivity, active oxygen species (AOS), electron spin resonance (ESR),

2,2,6,6-tetramethyl-4-piperidinol (TEMP), hydroxypropylmethylcellulose (HPMC)

Active oxygen species (AOS) generated under low pressure mercury lamp have been tried to apply for sterilization

of medical devices [1] and surface modification [2]. It is considered that effective AOS on the sterilization and

surface modification are excited singlet oxygen atom [O(1D)], excited singlet oxygen molecules (1O2), ground-state

oxygen atom [O(3P)] and ozone (O3) [3-5]. Of the four oxygen species, O3 has the lowest reactivity but the longest

lifetime. It is likely that the O3 acts on microorganism surfaces, and contributes to sterilization. But, we should not

ignore the potential contribution of the most highly reactive oxygen molecules and atoms such as 1O2, O(1D) and

O(3P), even if their lifetime is extremely short [5, 6]. It was difficult to measure exposure dose of the extremely short

lifetime AOS under the vacuum condition. We found that among the reactive oxygen species generated by

ultraviolet irradiation, the 1O2, with its high reactivity, was the principal species in the sterilization effect by analyses

of electron spin resonance (ESR) method using 2,2,6,6-tetramethyl-4-piperidinol (TEMP) as a spin-label reagent for

active oxygen incorporated polyvinyl alcohol (PVA) film [6]. However, the 1O2 can be trapped by the spin-label

reagent at the surface of the incorporated PVA film, and it is required to enhance the trap efficient of the 1O2. As the

PVA is one of gas barrier polymers, it is considered that the 1O2 is hardly permeable into the PVA film.

Hydroxypropylmethylcellulose (HPMC) is one of high oxygen permeable polymers, and we employed TEMP

incorporated the HPMC. In this study, we reveal detection sensitivity of the 1O2 under vacuum condition by using

spin trap agent incorporated the HPMC.

To avoid decomposition of the TEMP due to exposure of UV light, the TEMP incorporated HPMC film was

installed into a sterilization bag, in which the UV light is not permeable, but gases such as AOS are permeable.

Figure 1 shows ESR detection of excited singlet oxygen molecules (1O2), (a) without exposure of the 1O2, after the

exposure using (b) TEMP incorporated PVA film and (c) TEMP incorporated HPMC film. Sensitivity of TEMP

incorporated HPMC film for the 1O2 is higher than that of the TEMP incorporated PVA film, which relates to higher

diffusion constants of the HPMC and PVA. In this paper, we discuss permeation mechanism of 1O2 into the HPMC.

References:

[1] K. Yoshino, H. Matsumoto, T. Iwasaki, S. Kinoshita, K. Noda, S. Iwamori, J. Vac. Soc. Jpn. 54 (2011)

pp.467–473 (in Japanese).

[2] K. Hosoya, K. Oya, S. Iwamori, IEICE TRANSACTIONS on Electronics, E100-C (2017) pp. 137-140.

[3] H. Sugimitsu, The Basics and Application of Ozone, Korin, Tokyo, 1996, pp.24–29 (in Japanese).

[4] H. Okabe, Photochemistry of Small Molecules, 177–184, Wiley-Interscience, USA, 1978, pp. 237–247.

[5] T. Matsunaga, K. Hieda, S. Nikaido, Photochem. Photobiol. 54 (1991) pp.403-410.

[6] K. Yoshino, S. Iwamori: J. Photochem. & Photobiol. A: Chem., 328 (2016) pp. 148-153.

Fig. 1. ESR detection of excited singlet oxygen molecules (1O2), (a) without exposure of the 1O2, after the exposure using (b) TEMP incorporated PVA film and (c) TEMP incorporated HPMC film.


A PSS-free PEDOT transparent conductive film on the Hierarchical

Nanoporous Layer glass

K. Uchiyama, *T. Fujima

Department of Mechanical Engineering, Tokyo City University, 1-28-1 Tamazutsumi, Setagaya, Tokyo 158-8557,

Japan *[email protected]

Keywords: conductive polymer, PEDOT, porous glass

Transparent conductive films are widely required for various electric products like touch-panel devices. Indium

tin oxide (ITO) is a typical material for that application with a good balance between its conductivity and optical

transparency. Conductive polymers are gathering much attention as a transparent conductive film due to its rare-metal-

free composition, lightweight, flexibility and so on. Poly (ethylene-3,4-dioxythiophene) / poly (styrene sulfonic acid)

(PEDOT/PSS) is one of the promising candidate for practical application because of its conductivity, transparency

and chemical stability.

PSS in the PEDOT/PSS composite provides carrier for the conduction along the PEDOT chain as well as film-

formation easiness. Since the PSS molecule is not conductive and suppresses the conductivity of the PEDOT/PSS

film, reducing the PSS amount is a topic for higher conductive films. In this work, we combined the Hierarchically

Nano-porous Layer (HNL) glass1) with a PSS-free PEDOT film.

HNL glass was prepared as a substrate for the PEDOT film then coated by EDOT by spin-coating method.

Aqueous solution of a polymerization initiator, sodium persulfate, and a carrier dopant, benzene sulfonic acid, was

then dropped on the EDOT-coated HNL

glass to obtain a PSS-free PEDOT film.

Sheet conductivity of the films was

measured in a frequency range of between

50 Hz and 20 kHz using a four-probe

method with a voltage amplitude of 5V.

Fig. 1 shows the sheet resistivity

spectra of the PSS-free PEDOT film in

comparison with a commercially available

PEDOT/PSS (high-conductivity grade)

film on an untreated silicate glass. As seen

in the figure, the PSS-free PEDOT film

had a obviously better conductivity than

the commercially-available one in lower

frequency region than 1 kHz.

The PSS-free PEDOT film is another

candidate for a practical organic

conductive film with an optical

transparency better than 80%.

References :

1）T. Fujima, et al. Langmuir 30 (48), 14494-14497, (2014)

Fig. 1. Sheet resistivity spectra for our PEDOT film on the

HNL glass in comparison with a commercially available

PEDOT/PSS film on an untreated silicate glass.

103

104

105

AC

sh

eet

resi

stiv

ity [

10-1

100

101

102

103

104

Frequency[Hz]

PSS-free PEDOT

PEDOT/PSS (commercial)

Micron-scale patterning of conductive polymer thin films by microcontact

printing

*Y. Tomoyama1), T. Kinoshita1), and K. Noda1) 1)Department of Electronics and Electrical Engineering, Keio University, Yokohama, Kanagawa, Japan *[email protected]

Keywords: microcontact printing, soft lithography, conductive polymer, PEDOT:PSS,

Recently, printing techniques that can be applied to organic electronics have been intensely researched.

Microcontact printing (CP)[1] is one of the soft lithography techniques, which offers a simple and low-cost surface

patterning methodology with high versatility and micrometer accuracy. The patterning with CP generally employs

a hydrophobic micropatterned stamp made from poly(dimethylsiloxane) (PDMS) to transfer ink molecules on

arbitary surfaces. By using CP technique, organic thin films with well-defined structures can be fabricated. In this

work, micropatterning of a conductive polymer film was attempted with CP, and structures and electrical

properties of the micro-patterned polymer films were evaluated.

Firstly, we fabricated a master mold on a Si substrate, by using SU-8 3010 as a negative photoresist for

photolithography. Successively, a PDMS stamp was

prepared by using this master mold. Mixing ratio of the

PDMS resin and the curing agent was 10:1. A PDMS

stamp of microelectrode patterns with 10 m gap was

obtained.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonat

e) (PEDOT:PSS) was employed as an electrically

conductive ink for CP because of its high conductivity,

ductility and transparency. A simple ultraviolet (UV)

ozone cleaning process was applied to hydrophilize the

PDMS stamp surface before inking. A silicon substrate

with 200 nm-thick thermally grown SiO2 was also

treated with UV ozone cleaner for 30 minutes

beforehand. These conditions of the UV ozone

treatments give a large influence to the pattern shapes

of the stamped films. We confirmed that the

temperature control during the stamping process is also

quite important for preparing well-defined patterns of the polymer films. Actually, as shown in Fig.1, a microscale

PEDOT:PSS electrode pattern with a 20 m gap was successfully fabricated on condition that the PEDOT/PSS ink

was transferred from the stamp to the Si surface at 80°C for 10 minutes. The thickness of the stamped PEDOT/PSS

film was measured to be 13 nm with a commercial thickness monitor based on the microscopic spectrophotometry.

The electrical conductivity of the PEDOT/PSS film was estimated to be 140 S/cm by four probe method, suggesting

that the fabricated PEDOT:PSS film with CP will be available for contact electrodes of organic devices such as

thin-film transistors.

Reference 1) A. Kumar and G. M. Whitesides, Appl. Phys. Lett., 63(14), 2002-2004 (1993),

Fig.1. Optical microscope image of a PEDOT:PSS thin-film

micropattern transferred onto a SiO2 surface with CP

100 m

PEDOT:PSS

SiO2

PEDOT:PSS

N-type doping in PCBM thin films by using an imidazole-based dopant

*Y. Yoshihashi1), M. Matsubara2), A. Ito2), and K. Noda1)

1)Department of Electronics and Electrical Engineering, Keio University, Yokohama, Kanagawa, Japan, 2)Kyoto

University *[email protected]

Keywords: organic semiconductor, n-type doping, imidazole-based dopant, PCBM

Organic p-type doping with accepter dopants has been extensively studied. However, the number of studies on

organic n-type doping with donor dopants is much less than p-type doping because control of electron transfer from

a dopant to a host material is quite difficult on account of air

instability of conventional donor molecules. With this

background, we have focused on imidazole-based compounds as

solution-processable and pure organic n-type dopants. These

compounds are known as strong single-electron reductants [1],

and especially N-DMBI was used in order to control electrical

characteristics of n-channel organic transistors [2]. A molecular

structure of N-DMBI was presented in Fig. 1. In this work, we

newly synthesized N-DMBI and examined doping of N-DMBI to

a well-known solution-processable n-channel semiconductor,

phenyl C61 butyric acid methyl ester (PCBM).

First, we synthesized N-DMBI molecules according to a

previously reported procedure [1]. Then, N-DMBI doped PCBM

solution (in chlorobenzene) was dropcast onto Si substrates

covered with 200 nm-thick SiO2 layer. Doping concentrations of

N-DMBI were 0 and 10 wt%. After that, the dropcast films were

dried and heated at 80°C overnight to activate the dopants. The

above processes were performed in a N2-filled glovebox. After

Au electrodes (thickness: 25 nm) were deposited onto the PCBM

film surfaces by vacuum evaporation, we measured two-terminal

current-voltage (I-V) characteristics of PCBM films under a

vacuum condition (10-2 Pa) using a vacuum probing system.

Figure 2 shows two-terminal I-V characteristics of undoped

and N-DMBI doped PCBM films. The gap distance between the

two contact electrodes was 50 m. As shown in Fig, 2, doping

N-DMBI into PCBM increased the current value by four orders

of magnitude. The thickness of the undoped and N-DMBI doped

films was measured to be 100 nm and 30 nm, respectively. This

result suggests that the electric resistance of PCBM thin films

considerably decreased by N-DMBI doping, probably due to

carrier (electron) doping effects.

References 1) X.-Q. Zhu, M.-T. Zhang, A. Yu, C.-H. Wang, J.-P. Cheng, J.

Am. Chem. Soc., 130, 2501-2516 (2008).

2) P. Wie, J. H. Oh, G. Dong, Z. Bao, J. Am. Chem. Soc. 132,

8852- 8853 (2010).

Fig. 1. Molecular structure of N-DMBI.

Fig. 2. Two-terminal I-V characteristics of

(a) undoped and (b) N-DMBI doped PCBM thin films.

mailto:*[email protected]

Direct Observation of Negative Carriers Injected into a Transistor Structure

Observed by High-Sensitivity Photoelectron Yield Spectroscopy

K. Ikegami

1), H. Kinjo

1), T. Sato

1), Y. Tanaka

1)2), and *H. Ishii

1)2)3)

1)Graduate School of Science and Engineering,

2) Center for Frontier Science,

3)Molecular Chirality Research Center,

Chiba University, Chiba-shi, Chiba, Japan *[email protected]

Keywords: Operando Photoelectron Yield Spectroscopy, Negative Carrier, Electronic Structure, C60, Transistor

Electron affinity, As, is one of fundamental parameters to discuss the electric properties of N-type organic

semiconductors. The evaluation of As has been so far performed by using inverse photoemission spectroscopy

(IPES), in which the transition energy from a neutral molecule to an anion is observed (M+e- M

-+h). In practical

carrier transport process, not only the transition from M to M- but also M

- to M participates. Thus, the transition

energy for the latter case is also necessary to correctly understand carrier transport. Very recently, we have

succeeded to perform negative ion UV photoemission spectroscopy (NI-UPS) for anions captured at the surface of

Alq3 film with spontaneous orientation polarization [1]. The process of NI-UPS (M-+h M+e

-) is reversed to

IPES, and the ionization energy (often called detachment energy, Ds) of the anion should correspond to As at first

approximation. The observed value of Ds was almost 1eV larger than As, indicating the energy stabilization of the

anion by Coulomb interaction with positive polarization charge at the polarized surface. In this study, in order to

reveal the actual situation of free negative carrier states without effect by counter charge, operando photoelectron

yield spectroscopy (PYS) was performed for C60 transistor structure. PYS, in

which total photoelectron yield is measured as a function of incident photon

energy, has some advantages over UPS; feasibility even under

inhomogeneous electric field, toughness against sample charging, and longer

probing depth [2]. Such advantages gives us the expectation of direct

observation of free negative carrier states.

A bottom contact-type C60 FET structure [C60(5 or 15nm thick)/Au(50nm)

/TTC(C44H90)(30nm)/SiO2 (300nm) /p+-Si] was fabricated and transferred to

measurement chamber for PYS measurement. The wiring to source (S), drain

(D), and gate (G) electrodes were performed in ultrahigh vacuum condition as

in Fig.1.

Fig.2 shows the PYS spectra of C60 FET. When S, D and G are kept at -200V, the spectrum (labelled ) showed

an onset () around 4.3 eV due to the photoemission from Au electrodes underneath C60 over layer. As shown in the

transfer curve of the transistor (inset of Fig.2), the

drain current started to flow around VG=30V. Once

the VG was raised to 70V to inject electrons, and then

lowered to the same potential to S and D to measure

PYS. The obtained spectrum () exhibited a clear

threshold shift to lower energy side around 3.5eV,

which is smaller than As of IPES (4.0eV). After a

reversed VG bias (-50V) was applied to extract the

injected electrons (), the threshold moved to the

original position. These results strongly suggest that

the onset structure around 3.5 eV is due to the

photoemission from anion injected into the FET

structure. The onset indicated that the onset of Ds of

C60 is about 3.5 eV in FET structure. The observed

difference from the As of IPES will be discussed in

relation to the electron distribution in unoccupied

density-of-states and the relaxation effect of anion

state.

References :

1) H. Kinjo, H. Lim, T. Sato, Y. Noguchi, Y. Nakayama and H. Ishii et al, Appl. Phys. Express, 9, 021601(2016).

2) H. Ishii et al, Chap. 8 (pp. 131 -155) in Electronic processes in organic electronics: Bridging nanostructure,

electronic states and device properties, eds. by H. Ishii, K. Kudo, T. Nakayama, N. Ueno, Springer (2015).

Fig.1 C60 FET mounted on sample holder

Yie

ld /

arb

. units

6543Photon Energy / eV

PYS spectra: onset

Before appling VG

After appling VG = 70 V

After appling VG = -50 V

(C60: 5 nm)

10-10

10-8

10-6

I DS /

A

6040200VGS / V

VDS = 50 V

Transfer curve

(C60: 15 nm)

Fig.2 VG dependence of PYS spectra (C60: 5 nm), Inset: the

transfer curve of the transistor device (C60: 15 nm)

Yie

ld /

arb

. units

6543Photon Energy / eV

PYS spectra: onset

Before appling VG

After appling VG = 70 V

After appling VG = -50 V

(C60: 5 nm)

10-10

10-8

10-6

I DS /

A

6040200VGS / V

VDS = 50 V

Transfer curve

(C60: 15 nm)

Smart organic fluorescent materials based on aryl-ether amine: Stimuli

induced on-off fluorescence switching and structure property studies

*A. Kundu1), and S. P. Anthony1) 1)School of Chemical and Biotechnology, SASTRA University, Thanjavur-613401, Tamil Nadu, India *[email protected] (Corresponding author) Keywords: AIEE, OLED, External Stimuli

Smart fluorescent materials received strong attention in recent years due to the application potential in modern optoelectronic devices including OLEDs, displays, data storage, sensors, security inks and optical switches1,2.

Organic -conjugated molecules that showed strong fluorescence in solution often turned to be non-fluorescence in the solid state due to aggregation caused fluorescence quenching. In contrast, some classes of non-planar

-conjugated exhibited aggregation enhanced fluorescence in the solid state compared to solution3. The non-planarity of molecular structure could be exploited for switching the solid state fluorescence by external stimuli such as pressure, heat, solvent exposure and mechanical force. We have synthesized aryl-ether amine based simple non-planar Schiff base molecules (1-5) that showed aggregation induced enhanced emission (AIEE) in the solid state and demonstrated rare stimuli responsive fluorescence off-on switching and tuning. However, 1–5 did not show any fluorescence in solution state, which could be due to the free rotation of the single bond and isomerism of the imine (C=N)4. Hard grounding of 1 showed irreversible fluorescence tuning from greenish-yellow to green. Heating or solvent exposure to the grounded powder did not switch back the fluorescence. Interestingly, hard grounding of 2-5 lead to the quenching of solid state fluorescence, however, heating/solvent exposure produced clear bright fluorescence. Importantly, 2-5 exhibited reversible off-on fluorescence switching for several cycles without significant change of fluorescence intensity. PXRD studies suggest that the switching of dark to bright fluorescence and vice versa of 2-5 is due to the reversible change of crystalline to amorphous phase and more planarization of twisted structure. Single crystal analysis of 1 and 5 confirmed the twisted molecular conformation and strong intermolecular interactions in the crystal lattice that lead to AIEE by restricting the free rotation and rigidifying the fluorophores in the solid state. References : 1) M. W. Peczuh and A. D. Hamilton, Chem. Rev., 100, 2479–2494 (2000),

2) S. Hirata and T. Watanabe, Adv. Mater., 18, 2725–2729 (2006), 3) Y. Hong, J. W. Y. Lama and B. Z. Tang, Chem. Commun., 4332–4353 (2009), 4) J. Wu, W. Liu, J. Ge, H. Zhang and P. Wang, Chem. Soc. Rev., 40, 3483–3495 (2011).

Fig.1. Graphical representation of smart organic fluorescent materials based on aryl-ether amine

mailto:*[email protected]

Temperature Dependence of Electrical Conductivity on -(BEDT-TTF)2I3

Single Crystal by using 4-terminal Lamination Contact Electrode

T. Ueda

1), D. Yamamoto

1), Y. Okada

1,2) , H. Yamauchi

1) , *M. Sakai

1), and K. Kudo

1)

1) Department of Electrical and Electronic Engineering,

2)Center for Frontier Science, Chiba University, Japan

*[email protected]

Keywords: organic electronics, charge order, metal-insulator transition, 4-terminal measurement, -(BEDT-TTF)2I3

Recent years, strongly correlated electronic materials attract intensive interest all over the world. Strongly

correlated electronic materials naturally tend to cause electronic phase transition by a perturbation of electric or

magnetic field. Organic charge transfer complex, one group of the strongly correlated materials, consists of donor

and acceptor molecules and has carrier generated by the charge transfer from donor to acceptor molecules, therefore,

indicates various electronic phases, e.g. charge order phase, Mott

insulator phase and electronic ferroelectric phase. -(BEDT-TTF)2I3 is

well known organic charge transfer complex, and is famous in

metal-insulator transition at 135 K[1]

. -(BEDT-TTF)2I3 single crystal

indicates metallic conduction above 135 K, however, the electrical

conductivity steeply increases below 135 K and undergoes phase

transition to the insulating charge order phase induced by Coulomb

interaction. The difference in electrical conductivity between the metallic

and charge order phase reaches 4-5 order of magnitude.

Because the charge order phase in -(BEDT-TTF)2I3 is only observed

in single crystal, it is crucially important to establish electrical contact on

the surface of the single crystal. Electrical contact on organic single

crystals was conventionally established by using silver, gold, or carbon

paint in this field. However, it is always difficult to draw even a simple

2-terminal electrode pattern on a tiny single crystal by the carbon paint.

Moreover, drawing complicated electrode pattern, e.g. 4- or 6- terminal

electrode patterns, is almost impossible. On the other hand, Hall effect

on rublene single crystals with thickness of less than several 100 nm was

successfully observed by electrostatic lamination technique of thin single

crystal on Si substrate[2]

. However, this technique can not be adopted on

thick single crystals over approximately 1 m. Therefore, general way

for making electrode pattern has been desired in this field. In this work,

we present novel way named lamination contact electrode.

Our method is a kind of inversion of electrostatic lamination of single

crystals on Si substrate. Our lamination contact electrode was made of

electrode patterns fabricated by photolithography on a thin parylene thin

film with a thickness of 900 nm. Figure 1 (a) is a photograph of the

lamination contact electrode fabricated on a glass substrate. We peeled

off thin parylene thin film with a patterned electrode, then stuck on the

surface of -(BEDT-TTF)2I3 single crystal. The lamination contact

electrode film was softly stick onto the surface and spontaneously

establishes an electrical contact with crystal surface as seen in Figure

1(b). Because this contact is sufficiently soft, the lamination contact

electrode can be replaced and stuck again without making any scratch.

Figure 1(c) is observed temperature dependence of electrical resistance.

Metallic conduction above 135 K, metal-insulator transition at 135 K,

and rapid increase of electrical resistance in insulator (charge order)

region were clearly observed. We have confirmed that our lamination

contact electrode is also stable even in low temperature.

Acknowledgement

This work was supported by grant-in-Aid for scientific research (24560006) from MEXT, Japan.

References

1) K. Bender et al., Mol. Cryst. Liq. Cryst.,108, 359 (1984).

2) J. Takeya et al., Jpn. J. Appl. Phys., 44, L1393 (2005).

Figure 1 (a) Peeling of the lamination

contact electrode from the glass substrate.

(b) -(BEDT-TTF)2I3 single crystal

wrapped by 6-terminal lamination contact

electrode. (c) Temperature dependence of

electrical resistivity observed in

-(BEDT-TTF)2I3 single crystal with

lamination contact electrode.

Carbon nanofiber/SnO2 composite material for anode of lithium-ion battery

K. Takahashi1), J. Abe1), K. Kawase1), Y. Kobayashi1), and *S. Shiratori1) 1)Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa

223-8522, Japan. *[email protected]

Keywords: Lithium-ion battery, Carbon nanofiber, Nanostructured SnO2

Lithium ion batteries (LIBs) have been widely used as energy storage for several applications such as portable

electronics and electric vehicles. With the rapid development of portable electronics, improvement of LIBs

performance is demanded in terms of higher energy density or longer cycle life. SnO2 has higher theoretical specific

capacity (782 mAh g-1) than that of graphite (372 mAh g-1), which is used as an anode material of commercial

LIBs.[1] SnO2 has attracted much attention because of not only its high capacity but its high abundance and low

toxicity. However, SnO2 has poor conductivity and the large volume changes during lithiation and delithiation

process leads to pulverization of SnO2, which results in decreasing cycle life. To overcome these obstacles, there are

mainly two-approaches. One is to combine SnO2 with materials which possess good conductivity such as carbon

materials, and the other is to make nanostructured SnO2, which can suppress the volume change during cycles and

shorten the lithium ion migration distance.

In this study, we demonstrate SnO2/carbon nanofiber

composite material for anode of LIBs. Carbon nanofiber

(CNF) has good conductivity and highly porous structure

which can accommodate the huge volume change of SnO2.

We design nanostructured SnO2/CNF composite electrode

(denoted as CNF@SnO2) by simple method.

Carbon nanofiber was fabricated by electrospinning of

polyacrylonitrile (PAN) and two-step thermal treatment.

Subsequently, nanoneedle-like SnO2 layer was deposited on

CNF via hydrothermal synthesis[2]. CNF was immersed into

the nutrient solution and the SnO2 crystal growth took place

in an electric furnace at 95oC for 3 hours. After completing the

growth reaction, the sample was sufficiently washed with

deionized water and then annealed at 300oC for 1 hour.

As shown in Figure 1(a), the fabricated CNF has uniform

morphology with diameters of around 300 nm and highly

porous structure. The BET surface area of CNF was 157.1 m2

g-1. After hydrothermal synthesis of SnO2, needle-like SnO2

nano-crystal layer was deposited onto CNF surface uniformly

and densely (Figure 1(b)). Through the SnO2 growth, fiber

diameter slightly increased because of formation of SnO2

nanocrystal layer.

The rate performance of CNF and CNF@SnO2 electrode in

LIBs is investigated. As shown in Figure 2, in the first 5 cycles,

CNF@SnO2 electrode exhibited more than 250 percent higher

capacity than that of only CNF electrode. Even when the current

density was 2.5 A g-1, CNF@SnO2 electrode shows higher capacity than that of CNF with the 0.1 A g-1. Furthermore,

when the current density was returned to 0.1 A g-1, the capacity recovered to 90 % of its initial value, also

demonstrating good reversibility of CNF@SnO2 electrode.

In summary, we have demonstrated SnO2 and CNF nanocomposite with unique morphology and enhanced

electrochemical performances by simple method. CNF@SnO2 electrode had self-standing ability and flexibility,

which can be directly used as the working electrode of LIBs. CNF@SnO2 electrode exhibited 780.9 mAh g-1, which

is 250 percent higher capacity than that of only CNF electrode. This superior performances derived from high

theoretical capacity of SnO2, nano-crystal morphology of SnO2 layer, and high conductivity and porous structure of

carbon nanofiber. This nanocomposite electrode with enhanced electrochemical performances can be used for

lithium ion battery for portable electronics or electric vehicles.

References 1) L. Yang et al., Nano Energy, 2016, 30, 885.

2) H. Song et al., Nanoscale, 2013, 5, 1188.

Figure 1. SEM images of (a)CNF and (b)CNF@SnO2. Scale

bars: 1 µm

Figure 2. Rate capability of CNF and CNF@SnO2. (b) The electrochemical impedance spectrum (EIS)

profiles of CNF and CNF@SnO2 with fresh cells.

Carbon Nanofibers as Current Collectors for a Green Battery with Deep

Eutectic Catholyte

K. KAWASE1), J. ABE1), K. Takahashi1), Y. Kobayashi1), S. SHIRATORI1)

1Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University,

223-8522 Japan

E-mail: [email protected])

Keywords: carbon nanofibers, deep eutectic solvent, battery

The development of green energy technologies is one of the major issues in this century. Organic solvents, which

are highly volatile, flammable and toxic, has been mainly used for rechargeable batteries. As an alternative to this,

Deep Eutectic Catholyte (DEC) has been proposed[1]. The battery system with deep eutectic catholyte (DEC) can be

a distinct class of low cost and greener because DEC is non-flammable and is not required to be deal with inside dry

box. The current collector, as a necessary component to conduct electricity to DEC, substantially influence the

overall performance of the battery. Strong adhesion to the DEC and long-term stability and light weight are required.

Regarding to lithium ion battery, it has been reported that carbon materials show better performance than metal

collectors[2]. However, in the battery system with DEC, which was reported recently, the use of carbon materials as

current collector have not been reported yet. In this work, we apply carbon nanofibers (CNF) as current collectors to

conduct electricity to DEC because CNF have chemical stability, high surface area and low density. CNF have

showed good wettability and chemical stability to DEC, which leads to the practical use of a green battery.

DEC was prepared by mixing FeCl3·6H2O and urea in a molar ratio of 2/1. CNF were prepared by

electrospinning polyacrylonitrile (10 wt.%) dissolved in N,N-dimethylformamide and heating (280 °C in air and

1000 °C in N2). For a comparison, the mixture of carbon black and polyvinylidene difluoride was pasted on stainless

(SUS). The electrochemical properties were investigated using a cell with Li metal, organic electrolyte, separator,

solid electrolyte, DEC and current collectors (CNF and carbon black / SUS).

For chemical stability against DEC, DEC droplets were dropped on CNF, Al, Cu and SUS. After 140 hours,

CNF looked unchanged, whereas Al, Cu and SUS were partially dissolved, which indicates the use of metal

collectors will be limited. For wettability to DEC, dropped DEC was spread completely on CNF by capillary force,

while carbon black / SUS showed contact angle of 66°, which indicates CNF have larger contact area to DEC. Large

contact area is expected to lead low charge transfer resistance. In the battery system with CNF and carbon black /

SUS, open circuit voltage (OCV) were 3.7 V and 2.9 V, respectively. Based on theory, the OCV should be 3.8 V

because the reduction potential of Fe2+/Fe3+ is 0.77 V vs. SHE

while the reduction potential of Li/Li+ is -3.045 V vs. SHE. In

discharge and charge, constant currents (50, 100, 250 μA) were

applied for 5 minutes for each (Fig. 1). The battery with CNF

showed stable discharge and charge performance at different

currents and showed higher reaction potential related to higher

OCV than the battery with carbon black / SUS. At 50 μA, there is

almost no difference of discharge-charge potential gaps in both

batteries. At 250 μA, the battery with CNF had 0.2 V smaller

discharge-charge potential gaps than the battery with carbon black /

SUS. This can be because good wettability and high surface area of

CNF decrease charge transfer reaction of DEC.

In conclusion, we have demonstrated the battery system with

DEC and CNF. The battery showed stable discharge-charge

performance and had smaller discharge-charge potential gaps than a

battery with carbon black / SUS, which can be attributed to good

wettability against DEC and large surface area of CNF.

Furthermore, CNF showed better chemical stability than other

metals, which can lead long stable cycle performance. In order to

realize the practical use of a battery with DEC, the use of CNF as

current collector will be useful.

References 1.Y. Wang et al., Energy Environ. Sci., 2016, 9, 2267.

2. K. Wang et al., Adv. Funct. Mater., 2013, 23, 846.

Fig. 1. (a), (b) Short term (5 minutes) discharge-charge

cycle test at different current (50, 100, 250 μA) for the battery with CNF and with carbon black / SUS.

Fabrication of antifreeze infused anti-icing and antireflective coating via

spray Layer by Layer method

*T. Yamazaki, T. Moriya, K.Manabe, M. Tenjimbayashi, T. Matsubayashi, Y. Tsuge, M. Komine,

and S. Shiratori Graduate School of Keio University, Yokohama, Kanagawa, Japan, *[email protected]

Keywords: anti-icing, transparent, antifreeze, spray LbL

In cold regions, heavy snow causes serious damage to solar cells and frost decreases transmittance of windows. As

the solution, anti-icing coating is one of the most effective approach because it does not require additional energy

consumption. The anti-icing coatings on the surfaces of solar cells require for high transparency besides anti-icing

property.

In previous work, hydrophobic surfaces, for example, superhydrophobic surface (SHS) and slippery liquid-infused

porous surface (SLIPS) are investigated as anti-icing coating1),2),3). Superhydrophobic surface (SHS) repels super

cooled water (freezing rain) but it promotes ice nucleation inside micro-size structure due to it’s convex-concave

structure1). Slippery liquid-infused

porous surface (SLIPS) removes the

condensed droplets and suppresses

frost formation thanks to it’s low

contact angle hysteresis(2. However,

the lubricant loss by frost formation

leads to lose the anti-icing

property of SLIPS(3. On the other hand,

hydrophilic surfaces have recently attracted

many attentions as excellent anti-icing

coatings(4. For example, antifreeze

liquid-infused surface shows excellent

anti-frosting property because the antifreeze

depresses water vapor pressure and decrease

the probability of frost formation(4. However,

there are few reports of antifreeze

liquid-infused surface focuses on high

transparency. Therefore, the purpose of our

study is to fabricate highly transparent

antifreeze liquid-infused anti-icing coating.

Here, we fabricated that anti-icing coating

by spray Layer-by-Layer (spray LbL) method and following antifreezes infusion as schematically shown in Figure 1.

Polyethyleneimine (PEI) and Colloidal silica (SiO2) were used as cation and anion respectively, and we selected

Ethylene glycol (EG) as the antifreeze liquid.

The PEI/SiO2 base layer showed suprerhydrophilicity and this base layer made it possible to retain the uniform EG

layer. In addition, PEI/SiO2 base layer also decreases the refractive index and works as antireflective coating

because it forms the porous structure (Figure 2). The thickness of antifreeze liquid layer which base layer can retain

depends on the thickness of base layer. Therefore, though 8 and10 bilayers of PEI/SiO2 films showed the lowest

refractive index, we used 10 bilayers of PEI/SiO2 films as the base layer because the film thickness was thicker than

that of 8 bilayers.

The experimental results showed that frost-resisting property depended on the thickness of antifreeze layer, and it

suggested that the base layer which retains large amount of antifreeze layer exhibited extreme anti-frosting property.

References

1) Mishchenko, Lidiya, et al. ACS Nano 4.12 (2010): 7699-7707.

2) Kim, Philseok, et al. ACS Nano 6.8 (2012): 6569-6577.

3) Rykaczewski, Konrad, et al. Langmuir 29.17 (2013): 5230-5238.

4) Sun, Xiaoda, and Konrad Rykaczewski. ACS Nano 11 (2017): 906–917

Fig. 1. Fabrication process of highly transparent anti-icing coating with antifreeze.

Fig. 2. Film thickness and refractive index values as a function of the number of deposited bilayers of PEI/SiO2 assembled on glass.

Fig. 2. De-frosting test, (a) Illustration of the test, (b) Optical images of heater surface, (c) A ratio of Sde-frosting to Stotal

Facile two step method for Cu nanonetwork based flexible transparent heater

R. Yoshikawa1), P. Pecorelli2), T. Matsubayashi1), K. Manabe1), A. Testa2) L. Magagnin2) and *S.

Shiratori1) 1) Graduate School of Science and Technology, Keio University, Yokohama, Kanagawa, Japan, 2) Department of Chemistry, Materials and Chemical Engineering, Politecnico di Milano, Milano, Italy *[email protected]

Keywords: Transparent heater, electroless deposition, power efficiency, de-icing

Ice adhesion on the surfaces causes terrible problems such as decrease in photovoltaic performance or low

visibility of vehicle windows. To overcome these problems, many researchers have reported anti-icing coating, which

prevents ice formation. Superhydrophobic surfaces mimicking lotus leaf repels water before freezing. Slippery liquid

infused porous surfaces (SLIPS) inspired by pitcher plant are also effective for delaying frost formation by infused

liquid. However, these surfaces lose their performances within short-term. Therefore, it is still challenging topic to

prevent ice adhesion for long-term.1 Recently, de-icing heater, which melts ice by joule heat has attracted much

attention. Transparent conductive electrodes (TCEs), widely used in various electrical devices, have suitable potential

for transparent heater. Especially, metal nanowire based TCEs are considered as promising materials because of their

high conductivity, which enables high temperature with high transparency. Additionally, these heaters can apply to

curved surfaces because they have high durability for bending. To fabricate flexible TCEs, transfer step is needed to

prevent flexible substrate damaged by heat. In general, the nanowire is formed by high temperature heat treatment

from precursor on heat-durable substrate and it is transferred to flexible substrate.2 However, this additional step

hinders TCEs use in practical flexible devices due to increased fabrication cost and difficulty to enlarge them.

In this study, we propose facile two step fabrication method

for Cu nanonetwork based flexible transparent heater. After that,

we demonstrate de-frosting test to prove the high performance of

the heater. To simplify the fabrication method, we designed

selective electroless deposition method.3 In this method, polymer

nanofiber, which was prepared by electrospinning, was used as

template for metal nanonetwork. Then, the template was

metallized by electroless deposition in plating bath. By mixing

sensitizer in electrospun nanofiber, catalyst was only deposited

on nanofiber surfaces and whole nanonetwork was selectively

metallized in plating step.

Figure 1 shows the transmittance and sheet resistance of the

film with different plating time. These properties are easily

controlled by tuning plating time. We demonstrated de-frosting

test on peltier cooler set at -20oC (Fig. 2(a)). Fig. 2(b) shows

optical images of the heater during the test. The accumulated

frost gradually melted and the surface was completely cleared.

To quantify the de-frosting progress, we calculated de-iced area

by binarizing optical images. Fig. 2(c) shows a ratio of de-iced

area to total area. For the first few seconds, frost didn’t melt

because the surface temperature was still low. Then, de-iced area

rapidly spread with increase in surface temperature. Finally, the

ratio reached 100% at 33 s. This fast de-icing property comes

from rapid thermal response and excellent energy efficiency of

the heater confirmed by other measurement.

In conclusion, we designed facile wet process of Cu

nanonetwork based transparent heater. It showed excellent

performance in de-frosting test. This work may contribute to

develop fabrication process of transparent heater for de-icing on

practical applications.

References :

1) R. Gupta, et al., ACS appl. Mater. Interfaces, 8, 12559-12575(2016).

2) H. G. Im, et al., ACS Nano, 8 10973-10979(2014).

3) A.Testa, et al., Ind. Eng. Chem. Res., submitted.

Fig. 1. Transmittance and sheet resistance of the Cu nanonetwork based heater depend on the plating time.

Chirality of In-Plane Oriented Single-Walled Carbon Nanotubes Grown on

Al2O3(0001) Substrate under Free Electron Laser Irradiation *K. Honobe1), D. Kawaguchi1), S. Ishikawa1), T. Nagata1), N. Iwata1) and H. Yamamoto1) 1)College of Science & Technology, Nihon University, Funabashi, Chiba, Japan *[email protected]

Keywords Single-walled carbon nanotubes, CVD, Free electron laser, Growth orientation, Chirality

Recently single-walled carbon nanotubes (SWNTs) have attracted much attention as a

candidate of post-silicon materials because of characteristic electric properties. An important

technical requirement for electronic device applications of SWNTs is the control of chirality and/or

growth orientation. We have already succeeded in fabrication of all semiconducting SWNTs on

SiO2/Si substrates by in-situ irradiation of free electron laser (FEL) during a chemical vapor

deposition (CVD) process. [1] The FEL irradiation enhances the growth of SWNTs accompanied

by a specific bandgap, of which the energy corresponds to that of the irradiated FEL. The purpose

of this study is to control the growth orientation and/or the chirality of SWNTs on Al2O3 substrates

by using the FEL irradiation technique.

As catalysts Fe nano-particles were deposited on

Al2O3(0001) substrates by vacuum evaporation. On the

substrates SWNTs were grown by CVD using acetylenes

as a carbon source. The obtained SWNTs were

investigated comparing with the results under the

condition of 800 nm FEL irradiation and non-irradiation.

Figure 1 shows a typical dynamic force microscopy

(DFM) image of the surface of the SWNTs grown without

FEL irradiation. Surely an in-plane orientated growth

was confirmed. The Raman spectra of the SWNTs were

also investigated as shown in Figs. 2(a) and (b), in which

the crystalline quality was

evaluated from a G/D

peak ratio and the

diameter or chirality of

SWNTs were analyzed

from radial breathing

mode (RBM) peaks. In

this sample the metal/

semiconductor mixtured

phase was observed.

The results of the SWNTs

grown under FEL

irradiation aiming for the

chirality control are also

discussed.

Reference :

[1] K. Sakai, S. Doi, N. Iwata, H. Takeshita, H. Yajima, and H. Yamamoto, “Growth Position and

Chirality Control of Single-Walled Carbon Nanotubes”, IEICE Transactions, E94-C, 12 (2011)

pp.1861-1866.

Corresponding Author: K. Honobe

Tel: +81-47-469-5457 , E-mail: [email protected]

Fig. 1. DFM image of SWNTs grown on Al2O3(0001) substrate by CVD without FEL irradiation.

Fig. 2. Typical Raman spectra of SWNTs grown on Al2O3(0001) substrate by CVD without FEL irradiation. The spectra around G and D peaks (a) and around RBM peaks (b) are shown, which were observed using Raman excitation laser with the wavelength of 532 nm. The G/D peak ratio was about 8.7 in (a). In (b) the RBM peaks observed at 216 cm-1 and 230 cm-1 indicates the existence of metallic SWNTs with the diameter of 1.07 nm and 1.15 nm diameters(), respectively. Also the RBM peak at 173 cm-1 indicates semiconducting SWNTs having 1.43 nm diameter ().

SWNTs

G-band

D-band

Substrate

(a) (b)

：metal

: semiconductor

0 50 100 150 200 250 3000

1x109

2x109

3x109

4x109

5x109

Shee

t re

sist

ance

[s

q.]

Temperature [ ]

0 50 100 150 200 250 3000

500

1000

1500

Sh

eet

resi

stan

ce [s

q.]

Temprature [ ]

Fabrication and Electric Properties of Fe and Ca Intercalated Bilayer

Graphenes*N. Kuragane

1), T. Nagata

1), N. Iwata

1), H. Yamamoto

1)and H. Takahashi

2)

1)College of Science &Technology, Nihon Univ., Funabashi-shi, Chiba, Japan

2)College of Humanities and Science, Nihon Univ., Setagaya-ku, Tokyo, Japan*[email protected]

Keywords: Bilayer Graphene, Chemical vapor deposition, Intercalation, Electric property

We fabricated metal intercalated bilayer graphenes, in which an electron-exciton

coupling is expected to generate high temperature superconducting materials [1]. In this

study, Fe- and Ca-intercalated bilayer graphenes were prepared and their electric properties

were investigated.

Single-layered graphene sheets were synthesized on Cu foils by a chemical vapor

deposition method. The graphene/Cu foil was dipped in Fe(NO)3 solution to etch the Cu foil

and Fe or Ca atoms were left on the graphene using Fe(NO)3 or CaCl2 solutions. Metal

intercalated bilayer graphenes were fabricated by putting another graphene on the etched

graphene. The intercalation was confirmed by energy dispersive x-ray spectrometry.

Figure 1 shows the temperature dependence of a sheet resistance of the Fe-intercalated

bilayer graphene fabricated using (a) 0.06mol/L and (b) 0.12mol/L of Fe(NO)3 solutions.

The sheet resistances was 30 kΩ/sq. and 1300 Ω/sq., respectively. Semiconducting property

was observed in (a), and metallic conduction was observed in (b) over a wide temperature

range. The resistance slightly increased below about 30 K with decreasing temperature as

shown in Fig.1(b). It is expected that the heavier doping may be effective for generation of

superconductivity. Also Ca intercalation as a non-magnetic metal was done and electric

properties of the Ca-intercalated bilayer graphenes were studied. Furthermore the effect in

the electric property of each samples under high pressure of several GPa will be discussed.

References :

[1] J. Akimitsu, Parity, MARUZEN, 05(2008), pp.6-12.

Corresponding Author: N. Iwata

Tel: : +81-47-469-5457 , E-mail: [email protected]

Fig. 1 Temperature dependence of the sheet resistance of the Fe-intercalated bilayer graphene

fabricated using 0.06mol/L (a) and 0.12mol/L (b) of Fe(NO)3 solutions, respectively.

(a) (b)

Development of Organic Conductors Based on Orbital Degeneracy and Iodine

Bond Ability

*Y. Nakano1), Y. Oe1), Y. Takahashi1), M. Ishikawa1), H. Yamochi1), and M. Uruichi2) 1)Kyoto University, Sakyo-ku, Kyoto, Japan, 2)Institute for Molecular Science *[email protected]

Keywords: organic conductor, semiconductor, semimetal, orbital degeneracy, iodine bond

In order to develop the required physical properties in organic conductors, it is

necessary to control both molecular property itself and molecular arrangement, which are

strongly related to the electronic structure. High-symmetric molecules have degenerate

orbitals. Depending on oxidation state, the high spin state is realized according to Hund’s

rule. Orbital degeneracy is expected to contribute not only the increase in density of states

at Fermi level which improves a transition temperature of BCS-type superconductor, but

also the loosening of Mott criterion which sets a borderline between carrier delocalization

and localization. The high-symmetric molecule can also adopt a degenerate electronic

state, under the condition of which any non-linear molecule lower the symmetry and

energy to remove the degeneracy by Jahn−Teller effect. On the other hand, the concept of

crystal engineering based on the halogen bond is attractive for controlling the molecular

arrangement. Unlike the other halogens, iodine has a uniqueness that the electronegativity

is smaller than carbon, which does not cause a decrease in molecular electron donating

property even if it is introduced into some molecule. Additionally, iodine shows the strong

and directional I···X iodine bond within halogen family. Based on such a characteristics,

the iodine-containing organic conductors have been developed to construct a unique

structure and physical property. Therefore, it is of great interest to actively exploit such a

characteristics of orbital degeneracy and iodine bond. Here we report the organic

conductors composed of (a) BTT-based C3-symmetric molecule 1 and (b)

iodine-containing EDO-TTF-I.

(a) Charge transfer complex of 1 with TCNQ

Mixing and grinding 1 with TCNQ at the charged ratio of 1:TCNQ = 1:1.5 afforded black powder, which was

washed with acetonitrile to afford the charge transfer (CT) complex, Cw. The composition ratio of Cw was

estimated to be 1:TCNQ = 1:0.9 by elemental analysis. Applying Raman spectroscopy to the samples at various

charged ratios, it was indicated that TCNQ0 more than one equivalent relative to 1 is not reduced. In other words, 1

is not oxidized up to +2, but around +1. Considering no C≡N stretching signal in TCNQ0 on IR spectrum of Cw

and the elemental analysis, it seems that the washing with acetonitrile removed the excess TCNQ, and afforded the

CT complex regarded as (1•+)(TCNQ•−). The compressed pellets of Cw exhibited the semiconducting behavior. The

room temperature resistivity (ρRT) and activation energy (Ea) were ρRT = 2.4 × 104 Ω cm and Ea = 0.29 eV. The

magnetic susceptibility of Cw was 1.3×10−3 emu mol−1 at room temperature, and the temperature dependence was of

a localized spin system.

(b) EDO-TTF-I radical cation salts

Single crystals of EDO-TTF-I radical cation salts, (EDO-TTF-I)2X (X =PF6, AsF6, SbF6, NO3, and ClO4), were

obtained by electrocrystallization technique in absolute ethanol containing a corresponding tetrabutylammonium salt

as a supporting electrolyte. X-ray structural analysis revealed that EDO-TTF-I molecules form dimerized stacking

columns in a head-to-tail manner, which is referred to as a β′-type arrangement [1]. Iodine bonds between

EDO-TTF-I and anion and I···S short contacts between EDO-TTF-I molecules were also observed, leading to the

structural similarity in these salts. In the case of X = PF6, AsF6, SbF6, and NO3, the salts exhibited the

semiconducting behaviors. No splitting of C=C stretching modes was observed in the range of 4−300 K by Raman

spectroscopy, indicating the homogeneous charge distribution of EDO-TTF-I0.5+. Therefore, these salts are

considered as Mott insulators. As for the ClO4 salt, the semiconducting behavior was observed in the range of

190−300 K as is the case with the other salts. However, the ClO4 salt underwent the transition to metallic phase in

the range of 95−190 K along with unit cell doubling, and became semiconductive below 95 K. Also based on the

results of tight-binding band calculation and Raman spectroscopy, it is considered that with lowering of temperature,

the Mott-insulator-to-semimetal transition associated with structural phase transition occurs at 190 K, followed by

the semimetal-to-band-insulator crossover at lower temperature.

References [1] T. Mori, Bull. Chem. Soc. Jpn., 71, 2509-2526 (1998).


Strong Acceptors of Long N-heteroacenes based on Benzothiadiayole fused

Naphthalenediimides for Organic Electronics

Benlin Hu

1),

*Martin Baumgarten

1)

1) Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

* [email protected]

Keywords: Strong acceptor, Benzothiadiazole, Naphthalenediimide, N-heteroacenes, Pyrene

N-heteroacenes could exhibit promising electron transport behaviors since their high electron affinities, which are

expected to be less sensitive to degradation via oxidation or dimerization. Furthermore, varying the number, position

and valence state of nitrogen atoms in N-heteroacenes are able to yield a large family of structurally related

-backbone and make the properties more diverse, which may bring considerable freedom to design novel organic

semiconductors and provide good opportunities for exploring the structure-property relationships. Herein, we report

long N-heteroacenes including thiadiazoloquinoxaline and naphthalenediimide, which are strong

electron-withdrawing unit. The long N-heteroacenes show low LUMO energy level of ~-4.20 eV and onset

absorption edge of >1000 nm. The electronic properties of the long N-heteroacenes support the fabrication of a

proof-of-concept thin film transistor, and high electron mobilities are obtained. Single crystals were obtained to

explore the packing structures.

Scheme 1. The synthesis of long N-heteroacenes

Figure 1. Calculated HOMO (left) and LUMO (right) distribution of the long N-heteroacene.

References:

1) U. H. F.Bunz, J. U.Engelhart, B. D, Lindner, M. Schaffroth, Angew. Chem., Int. Ed., 52, 3810−3821 (2013).

2) U. H. F. Bunz, Acc. Chem. Res., 48, 1676-1686 (2015)

3) J. Li, Q. Zhang, ACS Appl. Mater. Interfaces, , 7, 28049−28062 (2015)

4) Q. Miao, Adv. Mater., 26, 5541−5549 (2014).

5) J. U.Engelhart, O.Tverskoy, U. H. F.Bunz, J. Am. Chem. Soc. 136 , 15166−15169 (2014).

6) B.Kohl, F. Rominger, M. Mastalerz, Angew. Chem., Int. Ed., 54, 6051−6056 (2014).

7) S. Ito, Y. Tokimaru and K. Nozaki, Chem. Commun., 51, 221-224 (2015)

8) D. Sakamaki, D. Kumano, E. Yashima and S. Seki, Angew. Chem. In. Ed., 54, 5404-5407 (2015)

9) S.Kato, T. Furuya, M. Nitani, N. Hasebe, Y. Ie, Y. Aso, T. Yoshihara, S. Tobita1 and Y. Nakamura, Chem. Eur.

J., 21, 3115-3128 (2015)

10) D. Timea, H. Manuel, B. Martin, Org. Lett., 13, 1936-1939 (2011)

11) D. Timea, B. Dirk, B. Gunther, B. Martin, J.Am.Chem.Soc., 133, 13898–13901 (2011).

Low-temperature printable IGZO field-effect transistors in low-rare-metal region for flexible displays

*H. Yamauchi1), H. Tanaka1), S. Shu1), Y. Okada2), M. Sakai1), M. Iizuka3), and K. Kudo1) 1) Graduate School of Engineering, Chiba University, 2) Center for Frontier Science, Chiba University, 3) Faculty of Education, Chiba University *[email protected] Keywords: solution process, low temperature process, IGZO TFT, low rare metal

Oxide semiconductors such as ZnO, InGaZnO (IGZO) can be used for transparent thin film transistors (TFTs), and apply to flexible active matrix organic light emitting diode (AMOLED). These transparent semiconductor materials can expand the effective aperture ratio of AMOLED in the stacked structure. However, most of IGZO-TFTs reported in literature were in In: Ga: Zn = 1: 1: 1 or In rich regions3-4). The reduction of rare metals, ie In and Ga, is desired from the point of resource depletion and low cost production. In addition, high temperature process is required in solution process IGZO TFTs due to cut the chemical bond in organic compounds containing in solution species. Therefore, flexible plastic films are not suitable as the substrate due to their low heat resistance.

We have reported relatively high performance of ZnO TFTs fabricated by low temperature (lower than 200°C) solution process using ultraviolet ozone (UV/O3) assisted treatment1-2). Furthermore, the TFT with ZnO film doped In and Ga as semiconductor layer, has high mobility and high On/Off ratio.

In this study, we focused on the low temperature process of low rare metal IGZO TFTs for flexible AMOLED displays. Figure 1 shows the composition ratio in this study and previous works. IGZO TFTs were fabricated by spin coating method using a solution at low rare metal composition ratio of In, Ga (In, Ga < 25%). Figure 2 shows comparison of drain current for different thermal process. The target current of TFT to drive AMOLED is approximately 5×10-3 A/m. From the experimental results, the current of IGZO TFT was achieved by the UV/O3 thermal treatment at lower than 300 . On the other hand, the target current was not obtained without UV/O3 except for the high temperature region. The UV/O3 assisted thermal treatment was found to be effective for lowering the process temperature of IGZO TFT manufacturing. Since UV light has high energy and strong oxidation effect of O3, UV/O3 treatment assists to decompose the chemical bond of unnecessary organic compounds.

These results obtained here demonstrate that IGZO TFTs for AMOLED can be fabricated in low temperature and low rare metal region, and UV/O3 assisted treatment is applied to various transparent oxide semiconductor device manufacturing (e.g. flexible AMOLED backplane, transparent integrated circuits, UV solar cell) in low cost.

Acknowledgments: The authors would like to thank Mr. H. Watanabe for helpful discussion. References: 1) A. B. M. Khafe et al., J. Nanosci. Nanotech., 16, 3168 (2016). 2) A. B. M. Khafe et al., Jpn. J. Appl. Phys., 53, 05FF07-1 (2014). 3) K. Umeda et al., J. Appl. Phys., 113, 184509 (2013). 4) G. H. Kim et al., Appl. Phys. Lett., 94, 233501 (2009).

UV/O3 treatment

Fig. 2. Drain current versus UV/O3 thermal treatment temperature.

Fig. 1. Composition ratio of IGZO.

Carbon/iron oxide composite nanofiber anode for lithium ion battery by electrodeposition

*Y. Kobayashi1), J. Abe1), K. Kawase1), K. Takahashi1) and S. Shiratori1) 1) Keio University *[email protected] Keywords: Lithium ion battery, iron oxide, electrodeposition, carbon nanofiber, morphology control Lithium ion batteries (LIBs) are indispensable devices for sustainable energy utilization and more energy and power density are required for further application. As for the anode, alternative material with high capacity to graphite is highly demanded. Therefore, we combined iron oxide, which is high-capacity material, non-toxic, abundant, and carbon nanofiber to improve cyclic performance. We used electrodeposition (ELD) method because ELD is facile, scalable and controllable. Fig.1 shows schematic illustration of the procedure for the synthesis of carbon/iron oxide composite nanofiber. In order to optimize the performance of the electrode, control of its morphology is necessary. In this study, herein, we investigated the relationship between the current during electrodeposition and the morphology of deposited iron oxide, and control its morphology to improve the battery performance.

Fig. 2 shows the TEM images of fabricated carbon/iron composite nanofiber with each loading current during ELD. As loading current increased, the morphology of deposited iron oxide became rougher and its surface area increased. This is due to rapid deposition of iron oxide on carbon nanofiber. Fig. 3 shows the discharge capacity of arbon/iron oxide composite nanofibers with each loading current in ELD. The composite nanofiber deposited at 5 A/g showed the highest capacity of 710 mAh/g at current loading of 0.05 A/g and 344 mAh/g at even high current loading of 2 A/g. Compared with the anode deposited at 1 A/g, its increased roughness and surface area lead to the improved rate capability: rough structure enables shorter lithium ion diffusion distance. As for the anode deposited at 25 A/g, it has needle-like structure and much larger surface area than other anodes, but exhibited lower capacity. This is because that excess surface area leads to formation of unstable solid-electrolyte interface. As a result, moderate increase of surface area leads to the improvement of the battery performance.

This study shows the possibility of the morphology control of electrode by electrodeposition and the improvement of the battery performance.

Fig. 3 Discharge capacity of carbon/iron oxide composite nanofibers with each loading current in electrodeposition.

(a) (b) (c) Fig. 2 TEM images of carbon/iron oxide composite nanofiber (loading current during ELD: (a) 1 A/g, (b) 5 A/g, (c) 25 A/g ).

Fig. 1 Schematic illustration of the procedure for the synthesis of carbon/iron oxide composite nanofiber.

Near infrared reflection film using 1-dimensional photonic crystal via

Layer-by-Layer method.

*C. Nakamura1), T. Matsubayashi2), K. Manabe2), Kyu-Hong Kyung3), and S. Shiratori2)

1) Keio Univ. Faculty of Sci. & Tech., Yokohama, Kanagawa, Japan, 2)Grad. Sch. Sci. Tech., Keio Univ., 3)SNT.co *[email protected]

Keywords: photonic crystal, optical thin film, infrared reflection, Layer-by-Layer

Energy saving is one of the most important issues in the

world. The energy consumption of cooling devise in

developing countries is expected to increase by 40 times in

2100 compared 20001. Therefore, near-infrared (IR)

reflection film which shut off sun energy without using

energy have attracted attention. In this work, we fabricate

1-dimensional photonic crystal which reflect infrared light

via Layer-by-Layer method (LbL)2. The fabricated films can

be applied to window glasses of buildings and it is expected

that temperature rise in the room can be prevented.

Infrared reflective films were fabricated using the LbL

method. Titanium (IV) -bis- (ammonium lactate)

dihydroxide (TALH) was used for the anion solution of the

high refraction layer, and SiO2 particle colloidal solution was

used for the anion solution of the low refraction layer. Poly

(diallyl dimethyl ammonium chloride) was used for both cation

solution.

From the Fresnel reflection in the multilayer film, when

d=λ/4n holds, reflected light of wavelength is strengthened.

When setting the reflection peak at 900 nm in the near infrared

region and substituting the refractive indices assumed from the

materials, n=1.7, d=132 nm for high refractive index layer and

n=1.3, d=173 nm for low refractive index layer are desired.

From Figure 1, the bilayer number of the high refraction layer

was 28 and the low refraction layer was 10. When we piled up

high and low layer 5 times alternatively, the fabricated film showed nearly 60% reflection at the wavelength of 900

nm (Fig. 2).

Fabricated film has infrared reflection property and is expected for providing energy saving characteristics

References 1) M. Isaac, et al., Energy policy 37.2, 507-521 (2009).

2) G. Decher, et al., Thin solid films 210, 831-835 (1992).

Fig. 1 Film thickness and refractive index with

different number of bilayer. (a: High refractive

index layer, b: Low refractive index layer)

Fig. 2 Transmittance of fabricated film.

A paper-based color-indicator organic dosimeter to detect and quantify a

dosage of ionizing radiation in a wide range

*R.F. Bianchi1), F.A. Lopes1)2), G.R. Ferreira1)3), M.R. Franco1), T. Schimitberger4) and L.O. de Faria5)

1) Universidade Federal de Ouro Preto, Ouro Preto – MG, Brazil, 2) Universidade de Viçosa, Campus Florestal – MG, Brazil, 3) Universidade dos Vales do Jequitinhonha e Mucuri, Janaúba – MG, Brazil, 4) Universidade Federal de Minas Gerais, Belo Horizonte – MG, Brazil, 5) Centro de Desenvolvimento da Tecnologia Nuclear, Belo Horizonte – MG, Brazil *[email protected] Keywords: Radiation sensor, innovation, flexible device, medical device. This paper presents the design and validation of a novel radiochromic film for selective detection of low-medium (0 to 10 kGy) gamma radiation (60Co) doses. This dosimeter is based on a printed fluorescent multilayer structure comprising a paper substrate having on at least one layer of copper phthalocyanine - DY220 (a green emitter material) on bottom, and at least one layer of poly[2-methoxy-5(2’-ethylhexyloxy)-p-phenylenevinylene] - MEH-PPV (a green-light absorber, red emitter and radiation sensitive polymer) on top. The effect of gamma radiation on the optical properties of DY220/MEH-PPV was described and we observed a strong correlation between radiation dose and fluorescent, color coordinates for CIE (1931) chromatic diagram and Pantone color reference of the dosimeter. The rate of these changes can be altered by manipulation of top-bottom layers to represent easily the radiation dose to be determined in a wide range. This versatile dosimeter has many uses in the field of food radiation for monitoring, quality assurance and control of gamma radiation process. This work was sponsored by Fapemig, CNPq, UFOP and INE0/CNPq agencies from Brazil.

FIG. 1: Multilayer organic dosimeter on paper-based substrate for monitoring, quality assurance and control of gamma radiation process.

References 1) G.R. Ferreira, C.K.B. de Vasconcelos, R.F. Bianchi, Med. Phys 36, 642 (2009) 2) C.K.B. de Vasconcelos and R.F. Bianchi, Sens. Act. B: Chem, 30 (2009) 3) G.R. Ferreira, A.M. Tannure, M.F. Siqueira, A.G.C. Bianchi, R.F. Bianchi, Sens. Act. B: Chem 240, 1003 (2017) 4) T. Schimitber, G. R. Ferreira, M.F. Saraiva, A.G.C. Bianchi, R.F. Bianchi, Sens. Act. B: Chem. 168, 131 (2012) 5) T. Schimitberger, G.R. Ferreira, L. Akcelrud, M. Saraiva, R. F. Bianchi, Med. Eng. Phys. 35, 140 (2013)

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