ENGINEERING TECHNOLOGY

In-situ growth of perovskite wafers enables low-dose direct X-ray detection imaging


Recently, Yu Xuefeng, researcher of the Institute of Advanced Materials Science and Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, and Liu Yanliang, associate researcher, and the team of Ge Yongshuai, a researcher at the Institute of Biomedical and Health Engineering, published an online report entitled PbI2-DMSO Assisted In-situ Growth of Perovskite Wafer for Sensitive Direct X-ray in Advanced Science Research paper by Detector. This study focuses on the scientific problems of high defect density and low carrier transport efficiency of perovskite wafer materials in perovskite direct X-ray detectors, and originally develops in situ growth technology for perovskite crystals, improves the photoelectric performance of perovskite wafers, and realizes efficient direct X-ray detection and scanning imaging. This work provides a new technical route for the preparation of high-sensitivity and high-resolution direct X-ray detectors, and is expected to be applied to high-end medical imaging diagnosis and chip nondestructive testing in the future.

X-ray detection is widely used in medical diagnosis and treatment, security inspection, industrial non-destructive testing and other fields. However, at present, commercial scintillator indirect X-ray detectors have problems such as low secondary photoelectric conversion efficiency and visible light dispersion, resulting in low detection sensitivity, high radiation dose and poor spatial resolution, which cannot meet the needs of high-end medical imaging and chip detection. In contrast, direct X-ray detectors based on semiconductor materials can directly convert X-rays into electrical signals through a single photoelectric conversion, with higher photoelectric conversion efficiency, detection sensitivity and spatial resolution. However, the current commonly used direct X-ray detection semiconductor materials face problems such as weak X-ray absorption (silicon, amorphous selenium), poor thermal stability (amorphous selenium), and high cost (cadmium telluride, zinc cadmium tellurium), which limits their promotion and application. Therefore, the development of new and efficient semiconductor photoelectric conversion materials is the key to the application of direct X-ray imaging detectors.

In recent years, metal halide perovskite semiconductors have attracted much attention in the field of direct X-ray detection due to their excellent intrinsic properties, such as heavy atom X-ray absorption, high carrier mobility and long lifetime. Perovskite materials have a detection sensitivity of up to 100,000 μC Gyair-1cm-2, which is better than commercial silicon, amorphous selenium, zinc cadmium tellurium. Studies have shown that perovskite wafers prepared by simple isostatic pressing methods are suitable for direct X-ray inspection with controllable size and thickness. However, perovskite wafers face the problems of incomplete crystal growth and high charge defect density, which affects the efficiency and working stability of X-ray detectors.

In this study, starting from improving the crystallinity of perovskite and reducing the defect density of perovskite wafers, PbI2-DMSO solid additives were innovatively developed, which promoted the in-situ regrowth of thick perovskite wafers, improved the crystallinity of materials, reduced defect density, and improved carrier mobility and lifetime. In this study, by slowing down the crystallization process of perovskite, reducing the nucleation density to form continuous large-grain perovskite wafers, further promoting the fusion of grain boundaries on the surface of the device and improving the charge transport performance, the high-efficiency perovskite direct X-ray detector was obtained. The detector has a sensitivity of 1.58×104μC Gyair-1cm-2, a minimum detectable dose of 410 nGyair s-1, and high-definition X-ray detection imaging is achieved by plane scanning. This work opens up new application directions for perovskite materials and provides an effective strategy for the preparation of high-quality perovskite wafers, which has considerable scientific value and application value.

In-situ grown perovskite wafers for highly sensitive direct X-ray detection

X-ray detection scan imaging

The research work has been supported by the National Natural Science Foundation of China, the National Natural Science Foundation of China Youth Science Foundation Project, the Chinese Academy of Sciences Youth Innovation Promotion Association, Shenzhen Municipality, etc. (Source: Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences)

Related paper information:https://doi.org/10.1002/advs.202204512

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