Toward Antimony Selenide Sensitized Solar Cells: Efficient Charge Photogeneration at spiro-OMeTAD/Sb2Se3/Metal Oxide Heterojunctions

Photovoltaic devices comprising metal chalcogenide nanocrystals as light-harvesting components are emerging as a promising power-generation technology. Here, we report a strategy to evenly deposit Sb2Se3 nanoparticles on mesoporous TiO2 as confirmed by Raman spectroscopy, energy-dispersive X-ray spectrometry, and transmission electron microscopy. Detailed study of the interfacial charge transfer dynamics by means of transient absorption spectroscopy provides evidence of electron injection across the Sb2Se3/TiO2 interface upon illumination, which can be improved 3-fold by annealing at low temperatures. Following addition of the spiro-OMeTAD hole transporting material, regeneration yields exceeding 80% are achieved, and the lifetime of the charge separated species is found to be on the millisecond time scale (tau(50%) similar to 50 ms). These findings are discussed with respect to the design of solid-state Sb2Se3 sensitized solar cells.