A major thrust of medical X-ray imaging is to minimize the X-ray dose acquired by the patient, down to single-photon sensitivity. Such characteristics have been demonstrated with only a few direct-detection semiconductor materials such as CdTe and Si; nonetheless, their industrial deployment in medical diagnostics is still impeded by elaborate and costly fabrication processes. Hybrid lead halide perovskites can be a viable alternative owing to their facile solution growth. However, hybrid perovskites are unstable under high-field biasing in X-ray detectors, owing to structural lability and mixed electronic–ionic conductivity. Here we show that both single-photon-counting and long-term stable performance of perovskite X-ray detectors are attained in the photovoltaic mode of operation at zero-voltage bias, employing thick and uniform methylammonium lead iodide single-crystal films (up to 300 µm) and solution directly grown on hole-transporting electrodes. The operational device stability exceeded one year. Detection efficiency of 88% and noise-equivalent dose of 90 pGy_air are obtained with 18 keV X-rays, allowing single-photon-sensitive, low-dose and energy-resolved X-ray imaging. Array detectors demonstrate high spatial resolution up to 11 lp mm⁻¹. These findings pave the path for the implementation of hybrid perovskites in low-cost, low-dose commercial detector arrays for X-ray imaging.

医学 X 射线成像的一个主要推动力是将患者获得的 X 射线剂量降至最低，直至达到单光子灵敏度。只有少数直接检测半导体材料（例如 CdTe 和 Si）证明了这种特性；尽管如此，它们在医疗诊断领域的工业应用仍然受到复杂且昂贵的制造过程的阻碍。混合卤化铅钙钛矿由于其易于溶液生长而可以成为一种可行的替代品。然而，由于结构不稳定和混合电子-离子电导率，混合钙钛矿在 X 射线探测器的高场偏压下不稳定。在这里，我们展示了钙钛矿 X 射线探测器的单光子计数和长期稳定性能是在零电压偏置的光伏操作模式下实现的，采用厚而均匀的甲基铵碘化铅单晶薄膜（高达 300 µm）和直接在空穴传输电极上生长的溶液。运行设备稳定性超过一年。88% 的检测效率和 90 pGy 的噪声当量剂量_空气是用 18 keV X 射线获得的，允许单光子敏感、低剂量和能量分辨的 X 射线成像。阵列检测器表现出高达 11 lp mm ^-1的高空间分辨率。这些发现为在用于 X 射线成像的低成本、低剂量商业探测器阵列中实施混合钙钛矿铺平了道路。