Shahrokhi Shamim, Dubajic Milos, Dai Zhi-Zhan, Bhattacharyya Saroj, Mole Richard A, Rule Kirrily C, Bhadbhade Mohan, Tian Ruoming, Mussakhanuly Nursultan, Guan Xinwei, Yin Yuewei, Nielsen Michael P, Hu Long, Lin Chun-Ho, Chang Shery L Y, Wang Danyang, Kabakova Irina V, Conibeer Gavin, Bremner Stephen, Li Xiao-Guang, Cazorla Claudio, Wu Tom
School of Materials Science and Engineering, Faculty of Science, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia.
School of Photovoltaic and Renewable Energy Engineering, University of New South Wales (UNSW), Sydney, NSW, 2052, Australia.
Small. 2022 May;18(21):e2200847. doi: 10.1002/smll.202200847. Epub 2022 Apr 28.
Hybrid halide perovskites have emerged as highly promising photovoltaic materials because of their exceptional optoelectronic properties, which are often optimized via compositional engineering like mixing halides. It is well established that hybrid perovskites undergo a series of structural phase transitions as temperature varies. In this work, the authors find that phase transitions are substantially suppressed in mixed-halide hybrid perovskite single crystals of MAPbI Br (MA = CH NH and x = 1 or 2) using a complementary suite of diffraction and spectroscopic techniques. Furthermore, as a general behavior, multiple crystallographic phases coexist in mixed-halide perovskites over a wide temperature range, and a slightly distorted monoclinic phase, hitherto unreported for hybrid perovskites, is dominant at temperatures above 100 K. The anomalous structural evolution is correlated with the glassy behavior of organic cations and optical phonons in mixed-halide perovskites. This work demonstrates the complex interplay between composition engineering and lattice dynamics in hybrid perovskites, shedding new light on their unique properties.
混合卤化物钙钛矿因其优异的光电性能而成为极具前景的光伏材料，这些性能通常通过诸如混合卤化物等成分工程来优化。众所周知，随着温度变化，混合钙钛矿会经历一系列结构相变。在这项工作中，作者使用一套互补的衍射和光谱技术发现，在MAPbI Br（MA = CH NH 且x = 1或2）的混合卤化物混合钙钛矿单晶中，相变被显著抑制。此外，作为一种普遍行为，多种晶体相在很宽的温度范围内共存于混合卤化物钙钛矿中，并且一种迄今未在混合钙钛矿中报道过的轻微扭曲的单斜相在高于100 K的温度下占主导。这种异常的结构演变与混合卤化物钙钛矿中有机阳离子和光学声子的玻璃态行为相关。这项工作展示了混合钙钛矿中成分工程与晶格动力学之间的复杂相互作用，为它们的独特性能提供了新的见解。
