1. Dye-Sensitized Solar Cells
Sonja A. Francis 7th March 2012

2. M. Skompska. Synthetic Metals 2010, 160, 1-15.
Solar Irradiation
Solar irradiation is the amount of radiant energy emitted by the sun per area and unit time for a given wavelength of light.
Visible IR 
M. Skompska. Synthetic Metals 2010, 160, 1-15.

3. Is Solar Energy Viable?
Photovoltaic potential GJ per 1kW capacity solar cell
Potential amount of solar energy collected annually in Alberta with a 1 kW capacity solar cell system
3.96 – 5.04 GJ
Residential Electrical Energy Usage in Alberta (2009)
> 32,000,000 GJ
Maximum solar system
capacity required
~ 8,300,000 kW  8.3 MW
J. Bell, T. Weis, Greening the grid, Powering Alberta’s future with renewable energy. 2009
Retrieved 18th March 2010.

4. General Solar Cell Structureh
Negative Terminal
Positive Terminal
Cell structure
Load
Electron flow in external circuit
T. Markvart, L.Castañer. “Principles of Solar Cell Operation” in Practical Handbook of Photovoltaics Fundamentals and Applications, 2003, Elsevier, Oxford, UK.

5. Types of Solar Cells Semiconductor solar cell Thin film solar cell
E.g. Crystalline silicon
Organic/Polymer solar cell
E.g. Fullerene/Poly-(p-phenylvinylene)
Thin film solar cell
E.g. CdS/CdTe
V. Fthenakis. Renewable Sustainable Energy Rev , 13,
Y. Cao et al. Sol. Energy Mat. Sol Cells 2010, 94,
M.A. Green, K. Emery, Y. Hishikawa, W. Warta, Prog. Photovolt.: Res. Appl. 2009, 17,

6. Dye-Sensitized Solar Cells (DSSCs)
Main components
Semiconductor electrode
Dye sensitizer
Redox couple in an electrolyte
Transparent counter electrode coated with a catalyst  
Retrieved 16th March 2010
V. Fthenakis. Renewable Sustainable Energy Rev , 13,
Y. Cao et al. Sol. Energy Mat. Sol Cells 2010, 94,

7. Semiconductor E.g. Semiconductor oxides TiO2 (anatase)
ZnO, SnO2, Nb2O5, In2O3
TiO2 (anatase)
High porosity (60%)
High stability
Wide band gap energy 3.2 eV ( 388 nm)
SEM
S. Mori, S. Yamigada, “TiO2-based Dye-Sensitized Solar Cell” in Nanostructure Materials for Solar Energy Conversion, T. Soga (Ed.), 2006, Elsevier.
M. Grätzel. Acc. Chem. Res. 2009, 42,

8. Sensitizer Dye Suitable dyes absorb strongly in the visible region.
(in DMF)
(in EtOH)
(in EtOH)
D. L. Officer et al. J. Phys. Chem. C, 2007, 111, 11760–11762.
H. Sugihara et al. Sol. Energy Mat. Sol. Cells 2010, 94, 297 – 302.

9. Sensitizer Dye Suitable dyes chemisorb to the semiconductor.
E.g. One molecule of N719 exhibiting bidentate binding to TiO2. surface
TiO2 surface
Y. Narita et al. Electrochem. Solid-State Lett. 2009, 12, B167 – B170.

10. Redox couple/Electrolyte
Iodide/Triiodide
I3- + 2e-  3I- h
Dye
3 I-
Counter electrode
Semiconductor
Electron transfer
Electron transfer
Electron transfer
Dye +
I3-
Electron flow
External Circuit
B. C. O’Regan, J. R. Durrant, Acc. Chem. Res. 2009, 42, 1799 – 1808.

11. Counter Electrode I3- 3I- I3-/I- Pt FTO
E.g. Platinum loaded on Fluorine-doped SnO2 (FTO) – a transparent conducting oxide (TCO)
Pt is an excellent catalyst for triiodide reduction
Rare and expensive
Incompatible with some electrolytes e.g. poly sulfide To
external circuit
I3-
2 e-
3I-
I3-/I- Pt
FTO
G. Boschloo; A. Hagfeldt. Acc. Chem. Res. 2009, 42, 1819 – 1826.

12. B. C. O’Regan, J. R. Durrant, Acc. Chem. Res. 2009, 42, 1799 – 1808.
Processes in the DSSC
Photo-excitation
Electron injection and dye-relaxation
Electron flow
Re-entry
Reduction of electrolyte
Dye regeneration (reduction)  D*    hυ  Ox 
Red
D/D+
Semiconductor
Dye
Electrolyte CE
B. C. O’Regan, J. R. Durrant, Acc. Chem. Res. 2009, 42, 1799 – 1808.

13. Electron transfer in the DSSC
VOC – open circuit voltage; maximum voltage the dye-sensitized solar cell can achieve.
ISC - short circuit current; maximum current achieved (no load).
LUMO
Conduction
Band
Fermi Level
VOC
Potential/V
Redox
Potential
Fermi
Level
HOMO
Semiconductor Dye Molecule Electrolyte Cathode
not drawn to scale
G. Boschloo; A. Hagfeldt. Acc. Chem. Res. 2009, 42, 1819 – 1826.

14. Electrical Losses in DSSCs
Dye relaxation
Recapture by oxidised electrolyte
Recapture by oxidised dye   
Red Ox
D+/D
Semiconductor
Dye
Electrolyte Pt
A. J. Bard; L. R. Faulkner. “Photoelectrochemistry and Electrogenerated Chemiluminescence” in Electrochemical Methods Fundamentals and Applications, 2nd Ed. 2001, Wiley, New Jersey, USA.

15. Most Efficient DSSC (11.1%)
J-V and Power curves
Incident radiation 100 mW/cm2
TiO2 semiconductor
Dye sensitizer
I- /I3- in ionic liquid electrolyte
JSC 20.9 mA/cm2
VOC V
L. Han. et al. J. Jpn. Appl. Phys. 2006, 45, L638 – L640.

16. Make your own solar cell at home
Retrieved 8th March 2012

17. Current Products Sony’s functional Hana-Akari DSSC lanterns.
G24 Innovations Back pack DSSC
0.5W under direct sunlight.
Claims 12 % efficiency.
P. Patel “Dye-Sensitized Solar to Go” in Technology Review October 2009, MIT Publications. Retrieved 18th March 2010
Sony design. Retrieved 18th March 2010.

18. Additional References
/tag/solar-panel/
Retrieved 16th March 2010
/solar-panels/miniature-pv-cells
Retrieved 16th March 2010
NRC PV Potential Interactive map, glfc.cfsnet.nfis.org/mapserver/pv/index.php?lang=e. Retrieved 18th March 2010.
Electricity Statistics. Retrieved 18th March 2010.
/~luzheng/research.html
Retrieved 16th March 2010