High Efficiency Solution Processed Sintered CdTe Nanocrystal Solar Cells: The Role of Interfaces
By Panthani, Matthew G.; Kurley, J. Matthew; Crisp, Ryan W.; Dietz, Travis C.; Ezzyat, Taha; Luther, Joseph M. & Talapin, Dmitri V.
Published in Nano Letters
2014
Abstract
Solution processing of photovoltaic semiconducting layers offers the potential for drastic cost reduction through improved materials utilization and high device throughput. One compelling solution-based processing strategy utilizes semiconductor layers produced by sintering nanocrystals into large-grain semiconductors at relatively low temperatures. Using n-ZnO/p-CdTe as a model system, we fabricate sintered CdTe nanocrystal solar cells processed at 350 °C with power conversion efficiencies (PCE) as high as 12.3%. JSC of over 25 mA cm -2 are achieved, which are comparable or higher than those achieved using traditional, close-space sublimated CdTe. We find that the VOC can be substantially increased by applying forward bias for short periods of time. Capacitance measurements as well as intensity- and temperature-dependent analysis indicate that the increased VOC is likely due to relaxation of an energetic barrier at the ITO/CdTe interface.