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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, 1-15. 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. 2009 http://pubs.pembina.org/reports/greeningthegrid-report.pdf. Retrieved 18 th March 2010. 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, 2746 - 2750. Y. Cao et al. Sol. Energy Mat. Sol Cells 2010, 94, 114 - 127. M.A. Green, K. Emery, Y. Hishikawa, W. Warta, Prog. Photovolt.: Res. Appl. 2009, 17, 320 - 326. 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, 2746 - 2750. Y. Cao et al. Sol. Energy Mat. Sol Cells 2010, 94, 114 - 127. www.chemphys.lu.se/research/subjects/cells/ 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, 1788 - 1798. SEM

8 8 Sensitizer Dye 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. (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 – 1808. h Redox couple/Electrolyte Iodide/Triiodide I 3 - + 2e -  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 – 1826. 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 – 1808. 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 – 1826. 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 0.736 V J-V and Power curves

16 Make your own solar cell at home http://www.wired.co.uk/magazine/archive/201 0/03/how-to/how-to-make-your-own-solar- cell- 16 http://www.youtube.com/watch?v=bVwzJEhM 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. http://www.sony.net/Fun/design/activity/sustainable/dssc.html. Retrieved 18th March 2010. Sony’s functional Hana-Akari DSSC lanterns.

18 18 Additional References http://solarpanelspower.net /solar-panels/miniature-pv-cells Retrieved 16 th March 2010 http://www.itechnews.net /tag/solar-panel/ Retrieved 16 th March 2010 http://www.ecf.utoronto.ca /~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 2010. Electricity Statistics. http://www.energy.alberta.ca/Electricity/682.asp. Retrieved 18 th March 2010.


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