Song Xin, Cui Qingyue, Liu Yucheng, Xu Zhuo, Cohen Hagai, Ma Chuang, Fan Yuanyuan, Zhang Yunxia, Ye Haochen, Peng Zhanhui, Li Ruipeng, Chen Yonghua, Wang Jianpu, Sun Huaming, Yang Zhou, Liu Zhike, Yang Zupei, Huang Wei, Hodes Gary, Liu Shengzhong Frank, Zhao Kui
Key Laboratory of Applied Surface and Colloid Chemistry, National 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.
Dalian National Laboratory for Clean Energy, iChEM, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China.
Adv Mater. 2020 Oct;32(42):e2003353. doi: 10.1002/adma.202003353. Epub 2020 Sep 15.
Metal-free halide perovskites, as a specific category of the perovskite family, have recently emerged as novel semiconductors for organic ferroelectrics and promise the wide chemical diversity of the ABX perovskite structure with mechanical flexibility, light weight, and eco-friendly processing. However, after the initial discovery 17 years ago, there has been no experimental information about their charge transport properties and only one brief mention of their optoelectronic properties. Here, growth of large single crystals of metal-free halide perovskite DABCO-NH Br (DABCO = N-N'-diazabicyclo[2.2.2]octonium) is reported together with characterization of their instrinsic optical and electronic properties and demonstration, of metal-free halide perovskite optoelectronics. The results reveal that the crystals have an unusually large semigap of ≈16 eV and a specific band nature with the valence band maximum and the conduction band minimum mainly dominated by the halide and DABCO , respectively. The unusually large semigap rationalizes extremely long lifetimes approaching the millisecond regime, leading to very high charge diffusion lengths (tens of μm). The crystals also exhibit high X-ray attenuation as well as being lightweight. All these properties translate to high-performance X-ray imaging with sensitivity up to 173 μC Gy cm . This makes metal-free perovskites novel candidates for the next generation of optoelectronics.
无金属卤化物钙钛矿作为钙钛矿家族的一个特定类别，最近已成为有机铁电体的新型半导体，并有望凭借其机械柔韧性、轻质和环保加工特性，实现ABX钙钛矿结构的广泛化学多样性。然而，自17年前首次发现以来，尚无关于其电荷传输特性的实验信息，仅有一篇对其光电特性的简短提及。本文报道了无金属卤化物钙钛矿DABCO-NH₄Br（DABCO = N-N'-二氮杂双环[2.2.2]辛烷鎓）大单晶的生长及其本征光学和电子特性的表征，并展示了无金属卤化物钙钛矿光电器件。结果表明，该晶体具有约1.6 eV的异常大的禁带宽度，以及特定的能带性质，其价带最大值和导带最小值分别主要由卤化物和DABCO主导。异常大的禁带宽度解释了接近毫秒级的极长寿命，从而导致非常高的电荷扩散长度（数十微米）。这些晶体还表现出高X射线衰减以及轻质的特性。所有这些特性转化为灵敏度高达173 μC Gy⁻¹ cm⁻²的高性能X射线成像。这使得无金属钙钛矿成为下一代光电器件的新型候选材料。
