Ultralow-dose X-ray imaging enabled by vertically homogeneous perovskite films

Artificial intelligence is rapidly pushing imaging and sensing toward automated, quantitative decision-making, heightening the demand for reliable low-photon-flux detection and imaging across infrared through X-ray regimes, yet developing detectors that truly operate effectively at ultralow photon fluxes has been a challenge. As a canonical instance, low-dose X-ray imaging operates under intrinsically sparse photon statistics, where Poisson fluctuations along the absorption depth couple to vertical transport non-uniformity and are statistically amplified at ultralow dose. Here we elucidate this materials-to-electronics bottleneck and develop a new liquid-phase growth and annealing strategy that eliminates thermal and mass-transport instabilities in conventional methods during crystallization, yielding perovskite films with exceptional vertical uniformity. This enables depth-independent charge collection, significantly reducing stochastic fluctuations in the readout and achieving a 10-fold reduction in image noise. In imaging applications, our detectors deliver high-quality X-ray imaging at an ultralow effective per-pixel integration dose of 40.6 nGy_air, setting a new benchmark for safe, high-quality clinical imaging.