Zhang Hai, Zhang Peijie, Xie Chenlong, Han Jiang, Xu Bin, Quan Zewei
Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong, 518055, China.
Adv Sci (Weinh). 2024 Jan;11(4):e2305597. doi: 10.1002/advs.202305597. Epub 2023 Nov 20.
Two dimensional (2D) hybrid metal halides (HMHs) usually exhibit free excitonic (FE) emission, and self-trapped excitonic (STE) emission can also be achieved by adopting appropriate halogens and organic cations. Recently, significant efforts have been made to modulate and then clarify the transformation and connection between these two types of excitonic emissions in 2D HMHs. In this study, intriguing pressure-tuned transitions between FE emission and STE emission are observed in 2D (C H N ) PbCl . In contrast, only FE emissions with tunable emission energies are observed in 2D (C H N ) PbBr which possesses a similar structure with (C H N ) PbCl under compression. Such distinct halide-dependent optical responses under pressure are experimentally revealed to arise from the intricate interplay among several factors in these HMHs, including the stiffness of the structure, the Coulomb force between the organic cations and the inorganic octahedra, and the magnitude of inorganic octahedral distortion. These high-pressure optical explorations can unravel the underlying interrelationship between the crystal structure and excitonic emission in 2D HMHs.
二维（2D）混合金属卤化物（HMHs）通常表现出自由激子（FE）发射，通过采用合适的卤素和有机阳离子也可以实现自陷激子（STE）发射。最近，人们付出了巨大努力来调控并阐明二维HMHs中这两种激子发射之间的转变和联系。在本研究中，在二维（C₅H₅NH）₂PbCl₄中观察到了FE发射和STE发射之间有趣的压力调谐转变。相比之下，在二维（C₅H₅NH）₂PbBr₄中，在压缩下其结构与（C₅H₅NH）₂PbCl₄相似，但只观察到了发射能量可调的FE发射。实验表明，这些HMHs中这种明显的压力依赖卤化物光学响应源于几个因素之间的复杂相互作用，包括结构的刚度、有机阳离子与无机八面体之间的库仑力以及无机八面体畸变的程度。这些高压光学探索可以揭示二维HMHs中晶体结构与激子发射之间的潜在相互关系。
