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view article: http://dx.doi.org/10.1039/C3EE43844A
Solid-state sensitized solar cells (SSCs) utilizing semiconductor absorbers overcome the issues of leakage and evaporation encountered in liquid-junction SSCs, and offer the potential for efficient, low cost photovoltaics. For widespread commercialization these solar cells require higher power conversion efficiency than is currently obtained with state-of-the-art devices. One critical component to this is the efficient extraction of photogenerated charges from the semiconductor absorber material. In this study, we decouple the two steps of hole transfer in the Sb2S3/CuSCN system: diffusion of holes in the Sb2S3 absorber layer, and transfer of these holes across Sb2S3–CuSCN interface. We find that interfacial transfer is the major limiting step in the thin (< 20 nm) Sb2S3 films used for high efficiency Sb2S3 photovoltaics. Decoupling of diffusion and interfacial transfer leads to a deeper understanding of the mechanism of hole transfer. This information has implications for the future design of semiconductor-based SSCs as it points to an important, often neglected interface, the absorber-hole conductor interface, which can play an important role in charge extraction.