An Environmentally Stable and Lead‐Free Chalcogenide Perovskite
Tushar Gupta, Debjit Ghoshal, Anthony Yoshimura, Swastik Basu, Philippe K. Chow, Aniruddha S. Lakhnot, Juhi Pandey, Jeffrey M. Warrender, Harry Efstathiadis, Ajay Soni, Eric Osei‐Agyemang, Ganesh Balasubramanian, Shengbai Zhang, Su‐Fei Shi, Toh‐Ming Lu, Vincent Meunier, Nikhil Koratkar
Abstract
Abstract 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 (BaZrS 3 ), a lead‐free chalcogenide perovskite, is reported. Photoluminescence and X‐ray diffraction measurements show that BaZrS 3 is far more stable than methylammonium lead iodide (MAPbI 3 ) in moist environments. Moisture‐ and light‐induced degradations in BaZrS 3 and MAPbI 3 are compared by using simulations and calculations based on density functional theory. The simulations reveal drastically slower degradation in BaZrS 3 due to two factors—weak interaction with water and very low rates of ion migration. BaZrS 3 photodetecting devices with photoresponsivity of ≈46.5 mA W −1 are also reported. The devices retain ≈60% of their initial photoresponse after 4 weeks under ambient conditions. Similar MAPbI 3 devices degrade rapidly and show a ≈95% decrease in photoresponsivity in just 4 days. The findings establish the superior stability of BaZrS 3 and strengthen the case for its use in optoelectronics. New possibilities for thermoelectric energy conversion using these materials are also demonstrated.