Liu Yucheng, Zhang Yunxia, Zhu Xuejie, Feng Jiangshan, Spanopoulos Ioannis, Ke Weijun, He Yihui, Ren Xiaodong, Yang Zhou, Xiao Fengwei, Zhao Kui, Kanatzidis Mercouri, Liu Shengzhong Frank
Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, Shaanxi Key Laboratory for Advanced Energy Devices, Shaanxi Engineering Lab for Advanced Energy Technology, Institute for Advanced Energy Materials, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an, 710119, China.
Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA.
Adv Mater. 2021 Feb;33(8):e2006010. doi: 10.1002/adma.202006010. Epub 2021 Jan 21.
Low ionic migration is required for a semiconductor material to realize stable high-performance X-ray detection. In this work, successful controlled incorporation of not only methylammonium (MA ) and cesium (Cs ) cations, but also bromine (Br ) anions into the FAPbI lattice to grow inch-sized stable perovskite single crystal (FAMACs SC) is reported. The smaller cations and anions, comparing to the original FA and I help release lattice stress so that the FAMACs SC shows lower ion migration, enhanced hardness, lower trap density, longer carrier lifetime and diffusion length, higher charge mobility and thermal stability, and better uniformity. Therefore, X-ray detectors made of the superior FAMACs SCs show the highest sensitivity of (3.5 ± 0.2) × 10 μC Gy cm , about 29 times higher than the latest record of 1.22 × 10 μC Gy cm for polycrystalline MAPbI wafer under the same 40 keV X-ray radiation. Furthermore, the FAMACs SC X-ray detector shows a low detection limit of 42 nGy s , stable dark current, and photocurrent response. Finally, it is demonstrated that high contrast X-ray imaging is realized using the FAMACs SC detector. The effective triple-cation mixed halide strategy and the high crystalline quality make the present FAMACs SCs promising for next-generation X-ray imaging systems.
半导体材料要实现稳定的高性能X射线检测，需要低离子迁移率。在这项工作中，报告了成功地将甲基铵（MA ）和铯（Cs ）阳离子以及溴（Br ）阴离子可控地掺入FAPbI晶格中，以生长出英寸尺寸的稳定钙钛矿单晶（FAMACs SC）。与原始的FA和I相比，较小的阳离子和阴离子有助于释放晶格应力，从而使FAMACs SC表现出更低的离子迁移率、更高的硬度、更低的陷阱密度、更长的载流子寿命和扩散长度、更高的电荷迁移率和热稳定性以及更好的均匀性。因此，由优质FAMACs SC制成的X射线探测器显示出最高灵敏度为(3.5±0.2)×10 μC Gy cm ，在相同的40 keV X射线辐射下，比多晶MAPbI晶片的最新记录1.22×10 μC Gy cm 高约29倍。此外，FAMACs SC X射线探测器显示出42 nGy s 的低检测限、稳定的暗电流和光电流响应。最后，证明了使用FAMACs SC探测器实现了高对比度X射线成像。有效的三阳离子混合卤化物策略和高结晶质量使目前的FAMACs SC有望应用于下一代X射线成像系统。
