Effects of QD surface coverage in solid-state PbS quantum dot-sensitized solar cells
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AbstractLead sulfide quantum dots (QDs) were grown in situ on nanoporous TiO 2 by successive ion layer adsorption and reaction (SILAR) and by atomic layer deposition (ALD), to fabricate solid-state quantum-dot sensitized solar cells (QDSSCs). With the ultimate goal of increasing QD surface coverage, this work compares the impact of these two synthetic routes on the light absorption and electrical properties of devices. A higher current density was observed in the SILAR-grown QD devices under reverse bias, as compared to ALD-grown QD devices, attributed to injection problems of the lower-band-gap QDs present in the SILAR-grown QD device. To understand the effects of QD surface coverage on device performance, particularly interfacial recombination, electron lifetimes were measured for varying QD deposition cycles. Electron lifetimes were found to decrease with increasing SILAR cycles, indicating that the expected decrease in recombination between electrons in the TiO2 and holes in the hole-transport material, due to increased QD surface coverage, is not the dominant effect of increased deposition cycles. © 2013 IEEE.
CitationRoelofs KE, Brennan TP, Trejo O, Xu J, Prinz FB, et al. (2013) Effects of QD surface coverage in solid-state PbS quantum dot-sensitized solar cells. 2013 IEEE 39th Photovoltaic Specialists Conference (PVSC). Available: http://dx.doi.org/10.1109/PVSC.2013.6744328.
SponsorsWe would like to thank the McGehee group at Stanford for the use of materials, equipment and expertise with the transient photovoltage measurements, and the Grätzel group at EPFL for supplying the 45 nm TiO2 paste. The quantum dot synthesis work was funded as part of the Center on Nanostructuring for Efficient Energy Conversion at Stanford University, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0001060. The device fabrication and mesurement work was supported by the Center for Advanced Molecular Photovoltaics, made by the King Abdullah University of Science and Technology (KAUST).