High open-circuit voltage in single-crystalline n-type SnS/MoO₃ photovoltaics

It has been recently reported that n-type single crystalline SnS exhibits a large band bending (∼1 eV) at the interface with MoO₃, which is a large work function material. In this study, we applied this interface to solar cells for the first time and evaluated its photovoltaic properties. The highest VOC achieved was 437 mV. Although this value is the highest ever recorded for SnS solar cells, it was lower than the expected value of 700–800 mV. The highest power conversion efficiency (PCE) was 4.4%. Based on an analysis of the device parameters, we propose methods for improving the device performance, including VOC, the short-circuit current, and PCE. The carrier-collection length of the n-type SnS single crystals was estimated to be ∼200 nm based on the external quantum efficiency measurements. Therefore, this study demonstrates that the VOC of SnS solar cells can be improved by fabricating a junction with MoO₃ thin films.