Di Jiayu, Li Haojin, Chen Li, Zhang Siyu, Hu Yinhui, Sun Kai, Peng Bo, Su Jie, Zhao Xue, Fan Yuqi, Lin Zhenhua, Hao Yue, Gao Peng, Zhao Kui, Chang Jingjing
State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, 710071 Xi'an, China.
Advanced Interdisciplinary Research Center for Flexible Electronics, Academy of Advanced Interdisciplinary Research, Xidian University, 710071 Xi'an, China.
Research (Wash D C). 2022 Oct 10;2022:9768019. doi: 10.34133/2022/9768019. eCollection 2022.
Exploring halogen engineering is of great significance for reducing the density of defect states in crystals of organic-inorganic hybrid perovskites and hence improving the crystal quality. Herein, high-quality single crystals of PEAPbX (X = Cl, Br, I) and their para-F (-F) substitution analogs are prepared using the facile solution method to study the effects of both -F substitution and halogen anion engineering. After -F substitution, the triclinic PEAPbX (X = Cl, Br) and cubic PEAPbX (X = I) crystals unifies to monoclinic crystal structure for -F-PEAPbX (X = Cl, Br, I) crystals. The -F substitution and halogen engineering, together with crystal structure variation, enable the tunability of optoelectrical properties. Experimentally, after the -F substitution, the energy levels are lowered with increased Fermi levels, and the bandgaps of -F-PEAPbX (X = Cl, Br, I) are slightly reduced. Benefitting from the enhancement of the charge transfer and the reduced trap density by -F substitution and halogen anion engineering, the average carrier lifetime of the -F-PEAPbX is obviously reduced. Compared with PEAPbI, the X-ray detector based on -F-PEAPbI perovskite single-crystal has a higher sensitivity of 119.79 C Gy ·cm. Moreover, the X-ray detector based on -F-PEAPbI single crystals exhibits higher radiation stability under high-dose X-ray irradiation, implying long-term operando stability.
探索卤素工程对于降低有机-无机杂化钙钛矿晶体中的缺陷态密度从而提高晶体质量具有重要意义。在此，采用简便的溶液法制备了PEAPbX（X = Cl、Br、I）及其对位-F（-F）取代类似物的高质量单晶，以研究-F取代和卤素阴离子工程的影响。-F取代后，三斜晶系的PEAPbX（X = Cl、Br）和立方晶系的PEAPbX（X = I）晶体统一为单斜晶系的-F-PEAPbX（X = Cl、Br、I）晶体。-F取代和卤素工程，连同晶体结构变化，实现了光电性质的可调性。实验上，-F取代后，能级降低，费米能级增加，-F-PEAPbX（X = Cl、Br、I）的带隙略有减小。受益于-F取代和卤素阴离子工程对电荷转移的增强和陷阱密度的降低，-F-PEAPbX的平均载流子寿命明显降低。与PEAPbI相比，基于-F-PEAPbI钙钛矿单晶的X射线探测器具有119.79 C Gy·cm的更高灵敏度。此外，基于-F-PEAPbI单晶的X射线探测器在高剂量X射线照射下表现出更高的辐射稳定性，这意味着具有长期的原位稳定性。
