Toward Antimony Selenide
Sensitized Solar Cells: Efficient
Charge Photogeneration at <i>spiro</i>-OMeTAD/Sb<sub>2</sub>Se<sub>3</sub>/Metal Oxide Heterojunctions
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Abstract
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 Sb<sub>2</sub>Se<sub>3</sub> nanoparticles on mesoporous TiO<sub>2</sub> 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 Sb<sub>2</sub>Se<sub>3</sub>/TiO<sub>2</sub> interface upon illumination, which can be improved 3-fold
by annealing at low temperatures. Following addition of the <i>spiro</i>-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 (τ<sub>50%</sub> ∼ 50 ms). These findings are discussed with respect
to the design of solid-state Sb<sub>2</sub>Se<sub>3</sub> sensitized
solar cells