Asymmetric Metal Halide Film With Suppressed Leakage Current for High Sensitive X-Ray Detection and Imaging
Youkui Xu, Yingtao Li, Guoqiang Peng, Qian Wang, Zhenhua Li, Haoxu Wang, Gang Wang, Zhiwen Jin
Abstract
Metal halides have been demonstrated to be promising candidates for X-ray detectors. However, its large leakage current caused by the severe ion migration and intrinsic defect substantially degrades device performance. In this work, an asymmetric BA2CsPb2I7-CsPbI3 planar heterojunction X-ray detector is designed to suppress the leakage current. Both experimental and theoretical calculations demonstrate that: 1) enlarged ion migration energy (0.80 eV) and conductivity mutation at the interface ensure stable baseline and suppress leakage current; 2) CsPbI3 ensures effective absorption of X-ray, while BA2CsPb2I7 induces larger bulk resistance, which is expected to achieve higher photocurrent and lower dark current. Finally, the obtained X-ray detector exhibits negligible baseline drift, faster response, and smaller leakage current compared to the CsPbI3 counterparts. Specifically, the device exhibits a detection limit of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.092 ~\mu $ </tex-math></inline-formula> Gy <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{air}$ </tex-math></inline-formula> /s, and the CsPbI3-based device was <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.63 ~\mu $ </tex-math></inline-formula> Gy <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{air}$ </tex-math></inline-formula> /s.