Are Chalcogenide Perovskites an Emerging Class of Semiconductors for Optoelectronic Properties and Solar Cell? †

Metal chalcogenide perovskites were proposed as potential solar cell material in 2015. The theoretical maximum solar cell efficiencies of some chalcogenide perovskites are ∼30%, similar to CH ₃ NH ₃ PbI ₃ perovskites. The foreseen advantages of chalcogenide perovskites are high thermal and aqueous stability along with nontoxic elemental composition. To date, a reasonable amount of computational and experimental work has been reported on the synthesis, electronic and optical properties of chalcogenide perovskites. Major experimentally studied compounds are AZrS ₃ (A = Ba and Sr), Ba ₃ Zr ₂ S ₇ , and LaYS ₃ , which have direct band gaps in the range 1.3 to 2 eV, along with strong light absorption coefficients and small effective masses of charge carriers. There are a few more compositions with similar properties that have been suggested by computational screening. In this perspective, we summarize both the computational and experimental progresses made in designing chalcogenide perovskites for optoelectronic properties. Then we discuss the material design challenges that need to be addressed in the coming years for successful solar cell application.