1938-8 Workshop on Nanoscience for Solar Energy Conversion · Workshop on Nanoscience for Solar...

1938-8

Workshop on Nanoscience for Solar Energy Conversion

Emilio PALOMARES

27 - 29 October 2008

Institute of Chemical Research of CataloniaAvinguda Paisos Catalans 16

43007 TarragonaSpain

Charge Recombination Studies in Hybrid Molecular Photovoltaic Devices

Charge Recombination Dynamics in

Molecular Photovoltaic Devices.

Dr. Emilio Palomares. ICREA Research Professor

Institute of Chemical Research of Catalonia (ICIQ).

e-mail: [email protected]

Always Different Interfaces

Molecular Solar Cells

Photons in....Electrons Out

Dye Sensitised Solar Cells

"Blend" Solar Cells

Two different approaches

Different Photovoltaic Devices

HTM/ DYE+ Regeneration

ETIO2/ DYE Injection

ETIO2/ HTM RECOMBINATION

ETIO2/ DYE+

RECOMBINATION

L-TAS

TCSPC

Charge Transfer Processes

TPV


E

HOMO

LUMO

ETIO2/ DYE+ injection

E

HOMO

LUMO

ETIO2/ DYE+ recombination

y = y0(�� /t )�

Fitting to KWW function


E

HOMO

LUMO

ETIO2/ DYE+ RECOMBINATION


E

HOMO

LUMO

ETIO2/ HTM RECOMBINATION

HTM


E

HOMO

LUMO

HTM

HTM/ DYE+ Regeneration


E

HOMO

LUMO

HTM

Overall charge transfer processes


E

HOMO

LUMO

HTM


10-12-10-9s


E

HOMO

LUMO

HTM


10-12-10-9s

10-4-10-6s


E

HOMO

LUMO

HTM


10-12-10-9s

10-4-10-6s10-3-101 s


E

HOMO

LUMO

HTM


10-12-10-9s

10-4-10-6s10-3-101 s

10-10-10-9 s


Device Characterisation

IPCE =Iph �1240

� � P0�100

�device = Isc �Voc � FF


Controlling "Dark" Electron transfer Reaction

ICIQ's Research


Dye absorption Kinetics

A = Amax (1� exp(�Kadst))

Lagergren's Equation

ICIQ's Research


Dye Injection kinetics

y = y0(�� /t )�

Injection into TiO2 CB occurs before 100 ps

Injection on Devices is slower. Nonetheless still faster than 250 ps

ICIQ's Research


TiO2/Dye+ charge transfer kinetics

y = y0(�� /t )�

TiO2/dye+ recombination half-lifetime ~3 x 10-4 s.TTT

ICIQ's Research


TiO2/electrolyte+ charge transfer kinetics

No TiO2 CB shift. No effect on the DOS by alkyl chains

Slow "dark" recombination dynamics

ICIQ's Research

Enhanced device efficiency

DSSC Devices

Increase in Current

Increase in voltage

ICIQ's Research

1

10

100

1000

10000

100000

0 5 10 15 20

PI1/Al2O

3

PI1/TiO2

Em

iss

ion

Co

un

ts (

a.u

.)

Time (ns)



0

1

2

3

4

5

6

7

550 600 650 700 750 800

PI1/Al2O

3

PI1/TiO2

Em

iss

ion

In

ten

sit

y (

a.u

.)

Wavelength (nm)


0

1 10-4

2 10-4

3 10-4

4 10-4

5 10-4

10-6

10-5

10-4

10-3

10-2

10-1

15 minutes4 hours14 hours

� O

.D.

Time (s)

SAME WL

0

5 10-5

1 10-4

1.5 10-4

2 10-4

10-6

10-5

10-4

10-3

10-2

10-1

15 minutes4 hours14 hours

� O

.D.

Time (s)

SAME OD


0

2

4

6

8

10

0 0.1 0.2 0.3 0.4 0.5 0.6

1 hour

4 hours

5 hours

14 hours

Ph

oto

cu

rre

nt

(mA

)

Voltage (V)

0.01

0.1

1

0.2 0.25 0.3 0.35 0.4 0.45 0.5

1 hour

14 hours

5 hours

Reco

mb

inati

on

Lif

eti

me (

s)

Cell Voltage (V)

ICIQ-Dyes

phenanthroline heteroleptic Ru(II) complexes


MO


-2.0

-3.0

-4.0

-5.0

E(eV)

(1.67) (1.70) (1.68)

(1.29)

(-2.97)

(-4.64)

(-2.89)

(-4.59)

(-2.91)

(-4.59)

(-3.54)

(-4.83) ( )

( 2 97)(-2 89)

( )

(-((((((( 4

-2.919191919119991111991199119111)))))))))))))))))))))))))))))))))))))

83)

Phen Me-PhenNH2-Phen NO2-Phen

Electron Injection


e--TiO2/Dye+ Recombination


0

5 10-5

0,0001

0,00015

0,0002

0,00025

0,0003

0,00035

0,0004

10-6

10-5

0,0001 0,001 0,01 0,1

N719

AR20

AR24

AR25

AR27

�O

.D.

Time (s)

0

6 10-5

0,00012

0,00018

0,00024

0,0003

600 650 700 750 800 850 900 950

100us

500us

�O

.D. (a

.u.)

Wavelength (nm)



0

2 10-5

4 10-5

6 10-5

8 10-5

0,0001

10-6

10-5

10-4

10-3

10-2

10-1

N719

TiO2

Cell Dark

White Light 800

White Light 999

Time (s)

� O

.D.

0

4 10-5

8 10-5

0,00012

0,00016

0,0002

0,00024

0,00028

10-6

10-5

10-4

10-3

10-2

10-1

AR25/TiO2:l

probe=800 nm

AR25/DSSC:lprobe

=800 nm

AR25/DSSC:lprobe

=1000 nm

Time (s)

� O

.D.



0

5 10-5

0,0001

0,00015

0,0002

10-6

10-5

10-4

10-3

10-2

10-1

AR24a/TiO2

:�probe

=800nm

AR24a/DSSC2

:�probe

=800nm

AR24a/DSSC2

:�probe

=1000nm

�O

.D.

Time (s)

0

4 10-5

8 10-5

0,00012

0,00016

0,0002

0,00024

0,00028

10-6

10-5

10-4

10-3

10-2

10-1

AR25/TiO2:l

probe=800 nm

AR25/DSSC:lprobe

=800 nm

AR25/DSSC:lprobe

=1000 nm

Time (s)

� O

.D.

Cell Characterisation


-2

0

2

4

6

8

10

12

14

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Jsc (

mA

/cm

2)

Voltage (V)

DSSC 208

�: 6,10 %

Voc: 0,66 V

Jsc: 13,55 mA/cm2

FF: 66,60 %

Device Area: 0,152 cm2

Dye: AR20

Electrolyte: AF04

Ligth: 100mW/cm2

Layers: TiO2 TiCl

4 (16+4) -2

-1

0

1

2

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

AR20

AR24-16

AR24-18

AR25

AR27-16

AR27-18

Ph

oto

cu

rre

nt

(mA

)

Voltage (V)

Dye Sensitised Solar Cellse--TiO2/Electrolyte+ Recombination

0

5 10-5

0,0001

0,00015

0,0002

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8

AR20

AR24a

AR24b

AR25

AR27b

AR27b

N719

Ch

arg

e (

C)

/cm

2

Voltage (V)

*

0

0,5

1

1,5

2

0 0,004 0,008 0,012 0,016 0,02

AR25

AR27

AR20

AR24

No

rma

lize

d I

nte

ns

ity

(a

.u.)

Time (s)

Organic solar cells

-- -

+ +

-----

-

+ +++

+

+++ ++

+

+

++

++

+++

-----

--------------

+

+++ ++

+

-

+

HOMO HOMO

LUMO LUMO

Organic solar cellsP3HT/PCBM d-TiO2/ P3HT/PCBM

Organic solar cells P3HT/PCBM

10-5

0,0001

0,001

10-6

10-5

0,0001 0,001 0,01

1:07

1:0.5

1:1

� O

.D.

Time (s)

Charge recombination

dynamics

dependent on P3HT/PCBM

ratio

Organic solar cellsITO/pentacene/C60/BCP/Al

-10

-5

0

5

-0.4 -0.2 0 0.2 0.4

0,1 Sun

1 Sun

dark

Js

c (

mA

/cm

2)

Voc (V)

FF=44.7%

�=0.54%

Voc=0.285

Isc=4.23mA/cm2

PENTACENE

ITO

4.8EV5.0EV C60

4.5EV

6.2EV

3.0EV

X.X

AL

BCP

Organic solar cellsITO/C60: ZnPc/DINPB/NDP2-DiNPB/NDP2-ZnPc/Au/Ag/Au

0

2

4

6

8

10

12

0 0.1 0.2 0.3 0.4 0.5 0.6

0.1 sun

0.5 sun

1 sun

Jsc(m

A)

Voltage (V)

�=2.70%

�=3.85%

�=3.59%

1

10

5 1016

1 1017

1.5 1017

2 1017

2.5 1017

3 1017

tau teoric

��

n (

μs

)

n (cm-3

)

Acknowledgments

Research Group Members and collaborators

Funding Agencies

Private Funding

1938-8 Workshop on Nanoscience for Solar Energy Conversion · Workshop on Nanoscience for Solar...

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