Emerging bismuth-based perovskite single crystals for advanced optoelectronics

Bismuth-based perovskite single crystals have emerged as a promising lead-free alternative to solve the toxicity and stability challenges of lead-based halide perovskites. Owing to their unique structural diversity, ranging from low-dimensional halide perovskites and double perovskites to layered perovskite oxyhalides, these materials exhibit exceptional optoelectronic properties, including tunable bandgap, high environmental stability, higher ion migration activation energy, and long carrier lifetime. This review provides a systematic overview of recent advances in bismuth-based perovskite single crystals. We first discuss their classification and crystal structure characteristics, followed by a detailed analysis of their electronic band structure, self-trapped exciton luminescence, charge carrier dynamics, and optical properties. Subsequently, various growth strategies are introduced for bismuth-based single crystals, including the slow evaporation method, temperature reduction crystallization method, anti-solvent diffusion method, hydrothermal method, melt crystallization method, and vapor transport method. The applications of these single crystals in high-performance photodetectors and X-ray detectors are comprehensively summarized. Finally, the key challenges and future directions toward scalable synthesis, surface passivation interface engineering, multifunctional integration, and emerging applications are discussed.