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Dye-Sensitized Solar Cells

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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 Structure
h 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  www.chemphys.lu.se/research/subjects/cells/ 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* 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


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