Abstract：
The development of perovskite direct X-ray detectors shows potential for advancing medical imaging and industrial inspection precision. To ensure the optimal energy conversion efficiency of X-rays for reducing radiation doses, it is necessary for perovskites with thicknesses reaching hundreds of micrometers or even several millimeters to be utilized. However, the nonlinear current response becomes uncertain with such high thicknesses. For instance, the prevailing theory regarding the rapid trapping and release of charges by shallow-level defects falls short in explaining the nonlinear current response observed in high-quality single-crystal samples. Moreover, a significant nonlinear current response can degrade the detection performance. Here, we elucidate peculiar parasitic and drift capacitance-induced nonlinear current responses in perovskites, which arise from bulk structural deficiencies and interface junction width variation in addition to shallow-level defects. Both theoretical analysis and experimental findings demonstrate the effective suppression of nonlinear current responses by establishing bulk heterojunctions and refining interface junctions. Consequently, we have successfully developed highly linear current-responsive detectors based on polycrystalline MAPbI3 thick films. Notably, these detectors achieve a record sensitivity of 2.3 × 104 μC·Gyair-1·cm-2 under 100 kVp X-ray irradiation with a low bias of 0.1 V/μm, enabling enduring and high-resolution X-ray imaging for high-density objects. Successful fabrication and testing of a 64 × 64-pixel flat-panel prototype detector affirm the widespread applicability of these strategies in rectifying nonlinear current responses in perovskite-based X-ray detectors.
摘要：
钙钛矿直接X射线探测器的开发显示出提高医学成像和工业检测精度的潜力。为了确保X射线的最佳能量转换效率，以降低辐射剂量，需要使用厚度达到几百微米甚至几毫米的钙钛矿。然而,非线性电流响应变得不确定与这样的高厚度。例如,关于浅层缺陷快速捕获和释放电荷的普遍理论不足以解释在高质量单晶样品中观察到的非线性电流响应。此外，显著的非线性电流响应会降低检测性能。这里,我们阐明了钙钛矿中特殊的寄生和漂移电容引起的非线性电流响应，除了浅层缺陷外，还由于体结构缺陷和界面结宽度变化而引起。理论分析和实验结果均表明，通过建立本体异质结和细化界面结，可以有效抑制非线性电流响应。因此,我们已经成功开发了基于多晶MAPbI3厚膜的高度线性电流响应检测器。值得注意的是,这些探测器在100kVpX射线辐照下以0.1V/μm的低偏压实现了2.3×104μC·Gyair-1·cm-2的记录灵敏度，为高密度物体提供持久和高分辨率的X射线成像。64×64像素平板原型探测器的成功制造和测试证实了这些策略在校正基于钙钛矿的X射线探测器中的非线性电流响应方面的广泛适用性。
