Zhang Peng, Zhang Guodong, Liu Lin, Ju Dianxing, Zhang Longzhen, Cheng Kui, Tao Xutang
State Key Laboratory of Crystal Materials, Institute of Crystal Materials , Shandong University , Jinan 250100 , P. R. China.
J Phys Chem Lett. 2018 Sep 6;9(17):5040-5046. doi: 10.1021/acs.jpclett.8b01945. Epub 2018 Aug 23.
All-inorganic perovskite CsPbBr has been considered as one of the star semiconductors due to its inspiring optoelectronic properties and higher stability than the organic-inorganic hybrid counterparts. The preparation of large-size single crystals with low trap density and the performance optimization on the devices still challenge the commercial application of this material. Here the large transparent CsPbBr single crystal (ϕ 24 mm × 90 mm) was grown by a modified Bridgman method. With the determination of crystallographic directions, the anisotropic optoelectronic properties were investigated for the first time. The result shows a high electron mobility (11.61 cm/(V s)) along the b axis, one order of magnitude higher than that along the c axis. Moreover, the photoresponse measurement yields a high responsivity (5.83 A/W) and external quantum efficiency (1360%) on the (001) plane irradiated by the 532 nm laser diode with 1 mW/cm under 10 V bias, which is a 305% enhancement compared with the (010) plane. Our study on anisotropic optoelectronic properties of CsPbBr will provide a significant approach to enhance the performance of single-crystalline devices.
全无机钙钛矿CsPbBr因其令人振奋的光电特性以及比有机-无机杂化同类物更高的稳定性，而被视为明星半导体之一。制备具有低陷阱密度的大尺寸单晶以及优化器件性能，仍然是这种材料商业应用面临的挑战。在此，通过改进的布里奇曼法生长出了大尺寸透明CsPbBr单晶（直径24毫米×90毫米）。通过确定晶体学方向，首次对其各向异性光电特性进行了研究。结果表明，沿b轴具有较高的电子迁移率（11.61厘米²/（伏·秒）），比沿c轴的电子迁移率高一个数量级。此外，在10伏偏压下，用1毫瓦/厘米²的532纳米激光二极管照射（001）平面时，光响应测量得出了较高的响应度（5.83安/瓦）和外量子效率（1360%），与（010）平面相比提高了305%。我们对CsPbBr各向异性光电特性的研究，将为提高单晶器件性能提供一条重要途径。
