Synthesis of Sulfide Perovskites by Sulfurization with Boron Sulfides

Chalcogenide perovskites (CPs), with general composition ABX3, where A and B are metals and X = S, Se, have recently emerged as promising materials for application in photovoltaics. However, the development of the CPs and their applications has been hindered by limitations of the available preparation methods. Here we present a new approach for synthesis of CPs, based on sulfurization of ternary and binary oxides or carbonates with in-situ formed boron sulfides. In contrast to the previously described approaches, the method presented here uses chemically stable starting materials and yields pure phase crystalline CPs within several hours, under low hazard conditions. CP yields over 95% are obtained at temperatures as low as 600 °C. The generality of the approach is demonstrated by preparation of CPs with compositions Ba-ZrS3, β-SrZrS3, BaHfS3, SrHfS3 and EuHfS3. Mechanistic insights about the formation of CPs are discussed.