Laboratory of Organic Optics and Electronics A Blue Exciton-Polariton Organic Light-Emitting Device...
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Transcript of Laboratory of Organic Optics and Electronics A Blue Exciton-Polariton Organic Light-Emitting Device...
Laboratory of Organic Optics and Electronics
A Blue Exciton-Polariton Organic Light-Emitting
Device
Laboratory of Organic Optics and Electronics
Scott Bradley, 6-1 (Electrical Engineering)
Master’s of Engineering Thesis Proposal
Images in this presentation are from:
Laboratory of Organic Optics and Electronics
Introduction• Project Motivation• Background
– Organic Light-Emitting Devices (OLEDs)
– J-Aggregates of Cyanine Dyes– Resonant-Cavity OLED
• Device Fabrication• Research and Resources• Experimental Methods• Timeline and Goals• Summary
Laboratory of Organic Optics and Electronics
Laboratory of Organic Optics and Electronics
What is a Polariton?
• Quasi-particle consisting of a photon and an exciton.– An exciton is an excited electron paired
with a hole—excited state of a molecule.
• Exciton and photon pass energy back and forth.
Laboratory of Organic Optics and Electronics
Project Motivation
• Exciton-polariton OLEDs have potential in optics applications.
• Existing work has established theory and created a red exciton-polariton OLED (J. Tischler).
• Work on a blue exciton-polariton OLED would allow for more research in fabrication.
Laboratory of Organic Optics and Electronics
Laboratory of Organic Optics and Electronics
+
electrons and holesform excitonsexcitons
(bound e--h+ pairs)
some excitons radiatesome excitons radiate
HOMO
LUMO
reco
mbin
atio
n re
gio
n
ETLHTL
E_
Background: Organic Light-Emitting Devices
Example HTL Example ETL
Laboratory of Organic Optics and Electronics
Laboratory of Organic Optics and Electronics
Background: J-Aggregates of Cyanine Dyes
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We use polar organic dye molecules…
…which line up when deposited carefully…
Called a J-Aggregate, named after Edwin Jelley of Kodak, who described the phenomenon in Nature in 1936.
300 400 500 600 700 8000.00
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0.12
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Ab
sorb
an
ce (
a.u
.)Wavelength (nm)
…and strongly absorb only one type of light.
Laboratory of Organic Optics and ElectronicsLaboratory of Organic Optics and Electronics
Background: Resonant-Cavity OLED• Create a cavity tuned to the J-Aggregate absorption wavelength using silver mirrors.
• Thin layers of silver are semi-transparent, so light is able get in and out of the cavity.
As long as the wavelength of light
Microcavity
Laboratory of Organic Optics and Electronics
Device Fabrication: Dip-Coating J-Aggregate-Polyelectrolyte Bi-Layers
Programmable Slide Stainer(1)
(1) Picture of Stainer from www.leica-microsystems.com(2) 400nm: Bucher, Kuhn, Chem Phys Lett 6 (1970) 183(3) 465nm: Fukumoto,et al. Thin Solid Films 327–329 (1998) 748(4) 550nm: Era, Adachi, Chem Phys Lett 178 (1991) 488(5) 623nm: Rousseau, et al., Langmuir 16 (2000) 8865(6) 890nm: Rotermund, et al. Chem Phys 220 (1997) 385
Wavenumber (cm-1)
Abs
orp
tion
(Nor
mal
ized
)
Wavelength (nm)
Fabrication Demonstrated Using Bi-Layer Deposition - Other J-Aggregates Likely Need Langmuir-Blodgett
10000 15000 20000 25000
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1.0
Pk 400 nm, FWHM 10 nm Pk 465 nm, FWHM 12 nm Pk 550 nm, FWHM 20 nm Pk 594 nm, FWHM 17 nm Pk 623 nm, FWHM 21 nm Pk 695 nm, FWHM 20 nm Pk 890 nm, FWHM 50 nm
110010
0090
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0
Laboratory of Organic Optics and Electronics
Research and Resources
• Plan to use dye with absorption around 465 nm.• Process variation to improve fabrication:
– pH variation of dye and polyelectrolyte solutions.– Dye concentration.– Number of layers.– Substrate variation (currently glass/ITO slides).– Different polyelectrolyte (currently PDAC).
• Might change mirror from metal to dielectric Bragg reflector (DBR).
• Planning to work with Prof. Vladimir Bulović.• LOOE has necessary fabrication equipment.
Laboratory of Organic Optics and Electronics
Experimental Methods• Electroluminescence measurements on patterned
devices. [LOOE]• Photoluminescence measurements using 408 nm
and higher energy lasers for excitation (fix excitation and scan through detection wavelengths). [LOOE]
• Photoluminescence-excitation measurements (fix detection and scan through excitation). [other CMSE groups]
• Reflection and transmission measurements using UV-Vis-NIR spectrometer. [CMSE Shared Analytical Lab]
Laboratory of Organic Optics and Electronics
Goals and Timeline
Goals:1. Build a blue exciton-polariton OLED.2. Research fabrication process parameters.
Timeline:– Currently doing related work in UROP position.– Be trained on necessary equipment by end of senior year.– Revisit M. Eng. thesis proposal and goals in spring 2004.– 6.728 in Fall 2004, 6.730 in Spring 2005.– Research process parameters to refine J-Aggregate bi-layer
deposition with 465 nm dye (fall 2004).– Fabricate blue exciton-polariton OLED (spring 2005).
Laboratory of Organic Optics and Electronics
Summary
• Blue exciton-polariton OLED fabrication and research could provide more information for further use of J-Aggregate-based devices.
• Further understanding of deposition process could help in creation of J-Aggregated-based devices in NIR and IR.