Hot‐Pressed CsPbBr3 Quasi‐Monocrystalline Film for Sensitive Direct X‐ray Detection

An X-ray detector with high sensitivity would be able to increase the generated signal and reduce the dose rate; thus, this type of detector is beneficial for applications such as medical imaging and product inspection. The inorganic lead halide perovskite CsPbBr₃ possesses relatively larger density and a higher atomic number in contrast to its hybrid counterpart. Therefore, it is expected to provide high detection sensitivity for X-rays; however, it has rarely been studied as a direct X-ray detector. Here, a hot-pressing method is employed to fabricate thick quasi-monocrystalline CsPbBr₃ films, and a record sensitivity of 55 684 µC Gy_air ^-1 cm^-2 is achieved, surpassing all other X-ray detectors (direct and indirect). The hot-pressing method is simple and produces thick quasi-monocrystalline CsPbBr₃ films with uniform orientations. The high crystalline quality of the CsPbBr₃ films and the formation of self-formed shallow bromide vacancy defects during the high-temperature process result in a large µτ product and, therefore, a high photoconductivity gain factor and high detection sensitivity. The detectors also exhibit relatively fast response speed, negligible baseline drift, and good stability, making a CsPbBr₃ X-ray detector extremely competitive for high-contrast X-ray detections.