An Environmentally Stable and Lead-Free Chalcogenide Perovskite

Organic-inorganic halide perovskites are intrinsically unstable when exposed to moisture and/or light. Additionally, the presence of lead in many perovskites raises toxicity concerns. Herein, a thin film of barium zirconium sulfide (BaZrS3), a lead-free chalcogenide perovskite, is reported. Photoluminescence and X-ray diffraction measurements show that BaZrS3 is far more stable than methylammonium lead iodide (MAPbI(3)) in moist environments. Moisture- and light-induced degradations in BaZrS3 and MAPbI(3) are compared by using simulations and calculations based on density functional theory. The simulations reveal drastically slower degradation in BaZrS3 due to two factors-weak interaction with water and very low rates of ion migration. BaZrS3 photodetecting devices with photoresponsivity of approximate to 46.5 mA W-1 are also reported. The devices retain approximate to 60% of their initial photoresponse after 4 weeks under ambient conditions. Similar MAPbI(3) devices degrade rapidly and show a approximate to 95% decrease in photoresponsivity in just 4 days. The findings establish the superior stability of BaZrS3 and strengthen the case for its use in optoelectronics. New possibilities for thermoelectric energy conversion using these materials are also demonstrated.