Antimony selenide as a buffer layer for high-efficiency and highly crystalline germanium monoselenide thin-film solar cells

Germanium monoselenide (GeSe) is a photosensing material that has recently received considerable research attention. Crystallization of the GeSe absorption layer is the key to determining the power conversion efficiency (PCE) of GeSe thin-film solar cells, which is influenced by substrate surface properties. In this study, we prepared an antimony selenide (Sb2Se3) buffer layer on an electron-transport layer (ETL) to modulate the subsequent growth of the GeSe absorption layer. The results showed that increasing the preparation temperature of the Sb2Se3 buffer layer (TSbSe) can effectively promote its crystallization. A highly crystalline GeSe absorption layer could be heteroepitaxially grown on a highly crystalline Sb2Se3 buffer layer. When TSbSe was 275 °C, the PCE of the GeSe solar cell was enhanced to 2.673 %. Our results will enable the fabrication of high-performance GeSe optoelectronic devices.