Revealing the role of intrinsic point defects in the stability of halide double perovskite Cs2AgBiBr6†
Abstract
An ab initio study of halide double perovskite (HDP) Cs2AgBiBr6 is presented. The antisites Br−2Cs and Bi+2Cs are found to be dominant acceptor- and donor-type defects, while the BiCs defect exhibits a deep transition level to form electron traps and Br migration has the lowest activation barrier. Our work provides a fundamental understanding of defect physics and chemistry in HDPs, highlighting that the Br-rich condition is preferable for improving the photovoltaic performance and chemical stability.