Recent reports of efficient solar cells and other optoelectronic devices based on halide perovskite semiconductors has generated broad interest in these materials; however, the halide perovskites have major issues related to their stability and toxicity. For this reason, Pb-free halide perovskites are being explored as nontoxic, and more stable alternatives. Within this family of semiconductors, Bi-based halide perovskites offer the potential to have similar optoelectronic performance as Pb-halide perovskites due to their similar electronic structures. Our recent findings demonstrate that Bi-halide perovskites have superior thermal and environmental stability compared to methylammonium lead iodide. Proof-of-concept devices demonstrate the potential of Bi-based perovskites for photovoltaics and other optoelectronic applications. We demonstrate that the morphology of Bi-halide films can be improved by annealing in solvent vapor, resulting in increased current density in photovoltaic devices. The improved understanding in the chemistry and processing of Bi-based semiconductors is a step towards next-generation optoelectronic devices with the performance and stability necessary for widespread commercialization.
