High-throughput exploration of halide perovskite compositionally-graded films and degradation mechanisms

The conventional approach to search for new materials is to synthesize a limited number of candidates. However, this approach might delay or prevent the discovery of better-performing materials due to the narrow composition space explored. Here, we fabricate binary alloy films with a composition gradient in a single shot in less than one minute. We apply this approach to study the stability of halide perovskites. We synthesize all possible binary compositions from MAPbI 3 and MAPbBr 3 and then study their optical properties, structure, and environmental stability in a high-throughput manner. We find that perovskite alloys experience three different degradation mechanisms depending on halogen content: bromine-rich perovskites degrade by hydration, iodine-rich perovskites by the loss of the organic component, and all other intermediate alloys by phase segregation. The proposed method offers an avenue for discovering new materials and processing parameters for a wide range of applications that rely on compositional engineering. High-throughput materials discovery can reduce the time taken to identify high-performing materials. Here, compositionally-graded films are fabricated in a binary halide perovskite system, of interest for solar cells, and their stability investigated during artificial aging.