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
Materials Sci ence & Technolog y
germanium
organic single crystals and amophous powders
Day of Chemistry, ZHAW Wädenswil, 21.6.2012
Silicon crystal structure
electron energylevels of a Si atom
ener
gy
energy bandsof a Si crystal
eV1band gap
Day of Chemistry, ZHAW Wädenswil, 21.6.2012
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
Day of Chemistry, ZHAW Wädenswil, 21.6.2012
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 y
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
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012
Solarmer
Polymer bulk-heterojunction concept
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012
Heliatek
Small molecule multilayer architecture
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012
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)
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012
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
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012 12
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
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012
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
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012
Ionic dyes for organic solar cells
Empa licensed
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012 15
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.
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012
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.
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012
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.
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012
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
Materials Sci ence & Technolog yDay of Chemistry, ZHAW Wädenswil, 21.6.2012
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
Day of Chemistry, ZHAW Wädenswil, 21.6.2012
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
Day of Chemistry, ZHAW Wädenswil, 21.6.2012
«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
Materials Sci ence & Technolog y
T. Geiger et al., Adv. Funct. Mater. 2009, 19, 2720–2727
Day of Chemistry, ZHAW Wädenswil, 21.6.2012
Verkehrshaus der Schweiz (2012)
http://youtu.be/UkLJKqw7zrs
Day of Chemistry, ZHAW Wädenswil, 21.6.2012
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
Materials Sci ence & Technolog y
Day of Chemistry, ZHAW Wädenswil, 21.6.2012
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)
Materials Sci ence & Technolog y
I-
Day of Chemistry, ZHAW Wädenswil, 21.6.2012
Day of Chemistry, ZHAW Wädenswil, 21.6.2012
Acknowldgement
Materials Sci ence & Technolog y
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