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Brian A. Korgel
Department of Chemical Engineering
The University of Texas at Austin
Solar cells, or photovoltaic devices, convert sunlight directly into electricity. These devices have been commercially available since the 1950’s and represent a relatively mature technology. But the cost is still high compared to conventional energy sources like fossil fuels—too high for widespread adoption. Spurred on by the rising cost of oil and the need for energy technologies with much less environmental impact, a tremendous amount of progress has been made in the past few years towards developing new, low-cost photovoltaic device technologies. Researchers are changing the way solar cells are made, printing solar cells like newspaper, putting them onto flexible plastic substrates or embedding them into fabric. In our research group, we have been developing a paint that can be applied to make solar cells and have demonstrated that this is indeed a viable approach to making photovoltaic devices. Our challenge now is to further engineer the materials to continue to improve device efficiency to commercially viable levels.
Recently, we observed peak external quantum efficiencies (EQE) of just over 125% in photovoltaic devices (PVs) of CuInSe
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nanocrystals prepared with a photonic curing process.
The extraction of more than one electron/hole pair as a result of the absorption of a single photon can occur if multiple excitons are generated and extracted. Multiexciton generation (MEG) in the nanocrystal films was substantiated by transient absorption spectroscopy. The performance and promise of these multiexciton solar cells will be discussed.