Li Kai, Wang Xinqiang, Li Xiaoqi, Wu Fafa, Zhang Fen, Wei Qingyin, Yue Zengshan, Luo Junhua, Liu Xitao
State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100, P. R. China.
State Key Laboratory of Structure Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, Fujian, P. R. China.
Inorg Chem. 2024 Jan 29;63(4):2275-2281. doi: 10.1021/acs.inorgchem.3c04286. Epub 2024 Jan 16.
In recent years, there has been a surge in research enthusiasm on searching for solid-state nonlinear optical (NLO) switching materials in halide perovskites owing to their exceptional structural flexibility, compositional diversity, and broad property tenability. However, the majority of reported halide perovskite NLO switching materials contain toxic elements (e.g., Pb), which raise significant environmental concerns. Herein, we present a novel lead-free multilayered halide perovskite NLO switching material, (BA)(EA)SnBr (, where BA is butylammonium and EA is ethylammonium). Driven by the stereochemically active lone-pair electrons of the Sn cation and the cage-confined effect of EA rotators, undergoes a phase transition with symmetry breaking from 4/ to 2, which gives rise to a highly efficient modulation of the quadratic NLO property (0.7 times that of KHPO) at a high temperature of 353 K. Furthermore, crystallographic investigation combined with theoretical calculations reveals that the efficient modulation of NLO properties in stems from the synergistic effects between stereochemically active lone pair-induced octahedral distortions and order/disorder transformation of organic cations. This study opens up an instructive avenue for designing and advancing environmentally friendly solid-state NLO switches in halide perovskites.
近年来，由于卤化物钙钛矿具有出色的结构灵活性、成分多样性和广泛的性能可调性，人们对寻找卤化物钙钛矿中的固态非线性光学（NLO）开关材料的研究热情高涨。然而，大多数已报道的卤化物钙钛矿NLO开关材料都含有有毒元素（如Pb），这引发了重大的环境问题。在此，我们展示了一种新型的无铅多层卤化物钙钛矿NLO开关材料，(BA)(EA)SnBr（其中BA是丁基铵，EA是乙基铵）。在Sn阳离子的立体化学活性孤对电子和EA转子的笼限效应驱动下， 发生了从4/到2的对称性破缺的相变，这在353 K的高温下实现了对二次NLO性质的高效调制（为KHPO的0.7倍）。此外，晶体学研究与理论计算相结合表明， 中NLO性质的有效调制源于立体化学活性孤对诱导的八面体畸变与有机阳离子的有序/无序转变之间的协同效应。这项研究为设计和推进卤化物钙钛矿中的环境友好型固态NLO开关开辟了一条具有指导意义的途径。
