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

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Presentation on theme: "Dye-Sensitized Solar Cells Sonja A. Francis 7 th March 2012."— Presentation transcript:

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

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

3 Is Solar Energy Viable? 3 J. Bell, T. Weis, Greening the grid, Powering Alberta’s future with renewable energy Retrieved 18 th March 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

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

5 Types of Solar Cells 5 Semiconductor solar cell – E.g. Crystalline silicon Organic/Polymer solar cell – E.g. Fullerene/Poly-(p-phenylvinylene ) V. Fthenakis. Renewable Sustainable Energy Rev. 2009, 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, Thin film solar cell – E.g. CdS/CdTe

6 Dye-Sensitized Solar Cells (DSSCs) Main components – Semiconductor electrode – Dye sensitizer – Redox couple in an electrolyte – Transparent counter electrode coated with a catalyst 6 V. Fthenakis. Renewable Sustainable Energy Rev. 2009, 13, Y. Cao et al. Sol. Energy Mat. Sol Cells 2010, 94, Retrieved 16 th March 2010

7 E.g. Semiconductor oxides – ZnO, SnO 2, Nb 2 O 5, In 2 O 3 TiO 2 (anatase) – High porosity (60%) – High stability – Wide band gap energy 3.2 eV (  388 nm) Semiconductor 7 S. Mori, S. Yamigada, “TiO 2 -based Dye-Sensitized Solar Cell” in Nanostructure Materials for Solar Energy Conversion, T. Soga (Ed.), 2006, Elsevier. M. Grätzel. Acc. Chem. Res. 2009, 42, SEM

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

9 9 Sensitizer Dye Suitable dyes chemisorb to the semiconductor. E.g. One molecule of N719 exhibiting bidentate binding to TiO 2. surface Y. Narita et al. Electrochem. Solid-State Lett. 2009, 12, B167 – B170. TiO 2 surface

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

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

12 hυhυ D/D + D*D* Ox Semiconductor DyeElectrolyte     CE 1.Photo-excitation 2.Electron injection and dye-relaxation 3.Electron flow 4.Re-entry 5.Reduction of electrolyte 6.Dye regeneration (reduction)  12 Processes in the DSSC  B. C. O’Regan, J. R. Durrant, Acc. Chem. Res. 2009, 42, 1799 – Red

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

14 D + /D D*D* Red Ox Semiconductor DyeElectrolyte  Pt 14 1.Dye relaxation 2.Recapture by oxidised electrolyte 3.Recapture by oxidised dye   A. J. Bard; L. R. Faulkner. “Photoelectrochemistry and Electrogenerated Chemiluminescence” in Electrochemical Methods Fundamentals and Applications, 2 nd Ed. 2001, Wiley, New Jersey, USA. Electrical Losses in DSSCs

15 Incident radiation 100 mW/cm 2 TiO 2 semiconductor Dye sensitizer I - /I 3 - in ionic liquid electrolyte 15 Most Efficient DSSC (11.1%) L. Han. et al. J. Jpn. Appl. Phys. 2006, 45, L638 – L640. J SC 20.9 mA/cm 2 V OC V J-V and Power curves

16 Make your own solar cell at home 0/03/how-to/how-to-make-your-own-solar- cell- 16 mD8&feature=player_embedded Retrieved 8 th March 2012

17 Current Products 17 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 18 th March 2010 Sony design. Retrieved 18th March Sony’s functional Hana-Akari DSSC lanterns.

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


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