Reactive close-spaced sublimation processed CuSbSe2 thin films and their photovoltaic application

CuSbSe2 is a promising absorber material for thin film solar cells because of its chemistry similarity to the well-known CuInSe2 but with low-cost and earth abundant component. Various methods have been employed to fabricate CuSbSe2 thin films with the best photovoltaic device achieving nearly 5% efficiency. Here, we develop a reactive close-spaced sublimation method to prepare high quality CuSbSe2 films via one evaporation process. In this method, a Cu layer is pre-sputtered onto the substrate, then reacts with Sb2Se3 vapor and its decomposition product Se, and finally generates single-phased CuSbSe2 films with large grains and proper doping density. This new strategy not only suppresses the decomposition of ternary chalcogenide CuSbSe2 but also is simple and applicable to other ternary semiconductors. Finally, based on this method, we have built prototype solar cells with a structure of AZO/CuSbSe2/CdS/i-ZnO/ZnO:Al/Au and obtained 3.04% power conversion efficiency for the champion device.