Reproducible high-quality perovskite single crystals by flux-regulated crystallization with a feedback loop.

Controlling the linear growth rate, a critical factor that determines crystal quality, has been a challenge in solution-grown single crystals due to complex crystallization kinetics influenced by multiple parameters. Here we introduce a flux-regulated crystallization (FRC) method to directly monitor and feedback-control the linear growth rate, circumventing the need to control individual growth conditions. When applied to metal halide perovskites, the FRC maintains a stable linear growth rate for over 40 h in synthesizing CHNHPbBr and CsPbBr single crystals, achieving outstanding crystallinity (quantified by a full width at half-maximum of 15.