Mao Yuhong, Guo Songhao, Huang Xu, Bu Kejun, Li Zhongyang, Nguyen Phuong Q H, Liu Gang, Hu Qingyang, Zhang Dongzhou, Fu Yongping, Yang Wenge, Lü Xujie
Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, China.
Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
J Am Chem Soc. 2023 Nov 1;145(43):23842-23848. doi: 10.1021/jacs.3c09375. Epub 2023 Oct 19.
Organic-inorganic halide perovskites possess unique electronic configurations and high structural tunability, rendering them promising for photovoltaic and optoelectronic applications. Despite significant progress in optimizing the structural characteristics of the organic cations and inorganic framework, the role of organic-inorganic interactions in determining the structural and optical properties has long been underappreciated and remains unclear. Here, by employing pressure tuning, we realize continuous regulation of organic-inorganic interactions in a lead halide perovskite, MHyPbBr (MHy = methylhydrazinium, CHNHNH). Compression enhances the organic-inorganic interactions by strengthening the Pb-N coordinate bonding and N-H···Br hydrogen bonding, which results in a higher structural distortion in the inorganic framework. Consequently, the second-harmonic-generation (SHG) intensity experiences an 18-fold increase at 1.5 GPa, and the order-disorder phase transition temperature of MHyPbBr increases from 408 K under ambient pressure to 454 K at the industrially achievable level of 0.5 GPa. Further compression triggers a sudden non-centrosymmetric to centrosymmetric phase transition, accompanied by an anomalous bandgap increase by 0.44 eV, which stands as the largest boost in all known halide perovskites. Our findings shed light on the intricate correlations among organic-inorganic interactions, octahedral distortion, and SHG properties and, more broadly, provide valuable insights into structural design and property optimization through cation engineering of halide perovskites.
有机-无机卤化物钙钛矿具有独特的电子构型和高度的结构可调性，使其在光伏和光电器件应用方面具有广阔前景。尽管在优化有机阳离子和无机骨架的结构特性方面取得了显著进展，但有机-无机相互作用在决定结构和光学性质方面的作用长期以来未得到充分重视且仍不明确。在此，通过施加压力调控，我们实现了对卤化铅钙钛矿MHyPbBr（MHy = 甲基肼鎓，CH₃NHNH₃）中有机-无机相互作用的连续调节。压缩通过增强Pb-N配位键和N-H···Br氢键来增强有机-无机相互作用，这导致无机骨架中出现更高的结构畸变。因此，在1.5 GPa时二次谐波产生（SHG）强度增加了18倍，并且MHyPbBr的有序-无序相变温度从常压下的408 K提高到工业上可实现的0.5 GPa时的454 K。进一步压缩引发了从非中心对称到中心对称的突然相变，同时带隙反常增加了0.44 eV，这是所有已知卤化物钙钛矿中最大的增幅。我们的研究结果揭示了有机-无机相互作用、八面体畸变和SHG性质之间的复杂关联，更广泛地说，为通过卤化物钙钛矿的阳离子工程进行结构设计和性能优化提供了有价值的见解。
