New trends in organic materials based solar cells · Flexible substrates are needed -> cheap...

Day of Chemistry, ZHAW Wädenswil, 21.6.2012Day of Chemistry, ZHAW Wädenswil, 21.6.2012

Materials Sci ence & Technolog y

New trends in organic materials based solar cells

Prof. Frank NüeschFunktionspolymereEmpa8600 Dübendorf

Day of Chemistry, ZHAW Wädenswil, 21.6.2012

Semiconductors

silicon

Cu Se

In

CI(G)S


germanium

organic single crystals and amophous powders


Silicon crystal structure

electron energylevels of a Si atom

ener

gy

energy bandsof a Si crystal

eV1band gap


Molecular crystal

energy levels of a molecule

Ene

rgie

energy «bands» of a molecular crystal

eV1band gap

merocyanine dye

Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012 5

Organic semiconductors are soft and ductile

Organic semiconductors have narrow absorption bands

Organic semiconductors, in particular dyes have high absorption coefficients exceeding those of inorganic semiconductors by 100 times

The properties of organic semiconductors can be tuned almost arbitrarily (absorption, solubility, crystallinity)

Organic semiconductors are normally insulators. Conductivity can be achieved by chemical/physical doping.

Organic semiconductors have a low charge carrier mobility, which is smaller by 3 to 6 orders of magnitude compared to inorganic semiconductors

Properties of organic semiconductors


Hans Meier, Bamberg 1960

Organic donor-acceptor junction

acceptor material donor material

conduction band

valence band

V

to the electrode

zur Elektrode

interface

donor materialacceptor material

Q. Tang, organic solar cell with 1% PCE (1986)


Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012

Development of organic solar cells

2

2000 2004 20120

4

6

8

1986 1998 2002 2006 2008 2010

PC

E (%

)

Kodak

Univ. Linz

Univ. Linz

Univ. Groningen SiemensNREL, Konarka, Univ. Linz

Plextronix

Univ. Santa BarbaraKonarka

Solarmer

Solarmer

Univ. Santa Barbara

Univ. Los Angeles

Univ. Princeton

Univ. Princeton

Cavendish Laboratory

Heliatek

small molecules(dyes)polymers

10amorphous silicon

7

HeliatekKonarka

Mitsubishi Chemical

Heliatek

Heliatek Solarmer


Solarmer

Polymer bulk-heterojunction concept


Heliatek

Small molecule multilayer architecture


Photographic dyes as organic semiconductors for solar cells

Extremely strong absorption

Narrow absorption bands from the UV to the NIR

Synthesis is known (upscaling possible)

Cost efficient (about 1% of polymer materials)

Well soluble (compatible with roll to roll processing)


N+ N

ClO4-

Cl

8

N+NClO4

-

7

H

H HNH2H2N

1) NaNO2 / HCl NN

H2NNH2

O

NN

NN

[CH3COOH]NN

SOO

O1)

2) NaClO4

N+N+

NN n

ClO4-+

N N n

Cl+ ClO4

-

OO

O

N+ N

Cl- Cl

H

[C2H5OH]

[Pyridine]

1 2

3 4

5

6

ClO4-

ClO4-

4

4

H

H

H2) SnCl2 / HCl

H

Yield: 85% Yield: 52%

Yield: 72% Yield: 68%

2

Yield: 91%

Yield: 86%

NN

ClO4- P 1n5

N N

Cl

ClO4-

+n

Synthesis of cyanine polymers

T. Geiger et al., Macromol. Rapid Commun. 2008, 29, 651–658


silicon

wavelength (nm)

Irrad

iatio

n de

nsity

(W

/m2 n

m)

0.5

1.0

1.5

400 600 800 1000 1200

abso

rban

ce solar emission

Polymeric cyanine dye films

NN

ClO4


Ultrathin absorber layers

pristinedoped 0.02 mol/mol NOBF4 absorption Bilayer device

Fan B., Castro F. A., Heier J., Hany R., Nüesch F., Org. Electron., 11, 2010, 583-588Hany R. et al., Prog. Photovoltaics 2011, 19, 851-857

~20 nm

aluminium

electron donor

+ Pol

- Pol

electron acceptor

photon

transp. electrode

N+NClO4

-

CyC

C60

e


Ionic dyes for organic solar cells

Empa licensed


Effect of counterions in bilayer cyanine devices

The device is biased for a certain time, then

IPCE is taken (at V=0)

400 500 600 700 8000

2

4

6

8

10

IPC

E, %

Wavelength, nm

0V + 4V1min + 4V3min + 4V8min + 4V13min + 4V20min + 4V25min

after5min after15min after30min after45min after75min after105min after125min after175min after225min

I

ITO

AlCy-ClO4 (70 nm)

MEH-PPV (30 nm)PEDOT:PSS (90 nm)

ITO

positive biasing

H. Benmansour, F. A. Castro, M. Nagel, J. Heier , R. Hany, F. Nüesch, Chimia, 2007, 61 (12) 787.


Formation of ionic junctions

PEDOT:PSS

Cy-ClO4MEH-PPV

Al

no biasing

PEDOT:PSS

Al

mainly oxidative charge transfer

positive biasing

only reductive charge transfer observed

Cy-ClO4MEH-PPV

H. Benmansour, F. A. Castro, M. Nagel, J. Heier , R. Hany, F. Nüesch, Chimia, 2007, 61 (12) 787.


Lifetime of organic solar cells

M. Jorgensen et al., Adv. Mater. 2012, 24, 580–612

Suren A. Gevorgyan et al., Solar Energy Materials & SolarCells, 95 (2011)1398–1416.


R2R processing

Flexible substrates are needed -> cheap barrier layers-> cost efficient, flexible and transparent electrode-> integrated bus bars

Low costs by high throughput (small depreciation)-> R2R fabrication of substrates-> R2R of the photoactive layers-> R2R production of encapsulation layers

first pruducts: charging bag solar cell from Konarka


Development of fabric electrodes (CTI project)

19

W. Kylberg, F. A. de Castro, P. Chabrecek, U. Sonderegger, B. Tsu-Te Chu, F. Nüesch, R. Hany, Advanced Materials 2011, 23, 1015-1019


New developments in dye sensitized solar cells

24.02.12 - The Interdisciplinary Committee of the World Cultural Council has selected Prof. Michael Grätzel as the winner of the ALBERT EINSTEIN World Award of Science 2012


«Transparent" dye sensitized solar cells

N

O

-O

N+

O

HO

300 400 500 600 700 800 900 1000-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

AM1.5

Spec

tral

Irra

dian

ce /

Wm

-2nm

-1

wavelenght / nm

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

A /

a.u

.

UV Vis NIR

Dyes in solutionHOMO

LUMO

visible red NIR

Synthesis

modeling

demonstrators

photovoltaic windows flexible, transparent PV active films tandem solar cells

absorption of squaraine dyes

synthesis

solar cell fabrication


T. Geiger et al., Adv. Funct. Mater. 2009, 19, 2720–2727


Verkehrshaus der Schweiz (2012)

http://youtu.be/UkLJKqw7zrs


Novel redox mediators

Jun-Ho Yum et al., nature communications | 3:631 | 2011

12.3% using porphyrin dye

Aswani Yella et al., SCIENCE VOL 334 (4), p. 629, 2011



New electrolyte systems

liquid small vapor pressure good ion diffusion 1 sun

0.3 sun0.1 sun

Irradiation with 0.8 sun/ 60°C

R. Harikisun, H. Desilvestro / Solar Energy 85 (2011) 1179–1188

Stability tests at 60oC conducted by Toyota Research(Asin)


I-



Acknowldgement


Roland HanyJakob HeierHui ZhangGaëtan WichtDaniel RentschMatthias NagelHadjar Benmansour (left)Fernando Castro (left) William Kylberg (left)Fan Bin (left)

Thomas GeigerIulia ShcherbakovaFahimeh NafezarefiSimon Kuster (left)Simone Hochleitner (left)

Empa (Dübendorf)

Jacques. E. MoserJelissa de JongheMichael GrätzelYum Ho

EPFL

Tobi MeyerAndreas Meyer

Solaronix

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New trends in organic materials based solar cells · Flexible substrates are needed -> cheap...

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