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Making Solar Cells. D. Venkataraman (DV) Department of Chemistry Umass Amherst dv@chem.umass.edu June 29, 2010. Photovoltaic Cells. Exciton. Active Material. Efficiency of Photovoltaic Cells Depend on Absorption in the Solar Spectrum Charge Separation Charge Mobility
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Making Solar Cells D. Venkataraman (DV) Department of Chemistry Umass Amherst dv@chem.umass.edu June 29, 2010
Photovoltaic Cells Exciton Active Material • Efficiency of Photovoltaic Cells Depend on • Absorption in the Solar Spectrum • Charge Separation • Charge Mobility • Charge Collection
Cost Organic Photovoltaic Devices Efficiency Stability End-User Application Home Depot/BP Solar Konarka Konarka
What is the Problem? Si or III-V Cells Exciton diffusion distance >100 nm Excitons loosely bound Organic/Hybrid/Dye-sensitized Exciton diffusion distance <10 nm Excitons tightly bound (Frenkel Excitons) Low dielectric constant 10 nm Gregg, B. A., Excitonic solar cells. Journal of Physical Chemistry B 2003,107 (20), 4688-4698.
Efficiency Cost Stability Active Material p-conjugated molecules /polymers Active Layer Morphologies Intrinsic Electrode/Active Layer Interfaces Device Fabrication/ Encapsulation Extrinsic
Organic Photovoltaic Cells Poly(3-hexylthiophene) (P3HT) Bulk Heterojunction Cells Efficiency ~ 5% 100 nm PCBM – [6,6]-phenyl-C61-butyric acid methyl ester Padinger, F.; Rittberger, R. S.; Sariciftci, N. S., Effects of postproduction treatment on plastic solar cells. Advanced Functional Materials 2003,13 (1), 85-88. Ma, W. L.; Yang, C. Y.; Gong, X.; Lee, K.; Heeger, A. J. "Thermally stable, efficient polymer solar cells with nanoscale control of the interpenetrating network morphology," Advanced Functional Materials 2005, 15, 1617-1622.