Li Chuanzhao, Yang Jin, Su Fuhai, Tan Junjun, Luo Yi, Ye Shuji
Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, 230026, Hefei, China.
Key Laboratory of Materials Physics, Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, 230031, Hefei, China.
Nat Commun. 2020 Oct 30;11(1):5481. doi: 10.1038/s41467-020-19330-7.
The chemical nature of the organic cations governs the optoelectronic properties of two-dimensional organic-inorganic perovskites. But its mechanism is not fully understood. Here, we apply femtosecond broadband sum frequency generation vibrational spectroscopy to investigate the molecular conformation of spacer organic cations in two-dimensional organic-inorganic perovskite films and establish a correlation among the conformation of the organic cations, the charge carrier mobility, and broadband emission. Our study indicates that both the mobility and broadband emission show strong dependence on the molecular conformational order of organic cations. The gauche defect and local chain distortion of organic cations are the structural origin of the in-plane mobility reduction and broad emission in two-dimensional organic-inorganic perovskites. Both of the interlayer distance and the conformational order of the organic cations affect the out-of-plane mobility. This work provides molecular-level understanding of the conformation of organic cations in optimizing the optoelectronic properties of two-dimensional organic-inorganic perovskites.
有机阳离子的化学性质决定了二维有机-无机钙钛矿的光电特性。但其机制尚未完全理解。在此，我们应用飞秒宽带和频振动光谱来研究二维有机-无机钙钛矿薄膜中间隔有机阳离子的分子构象，并建立有机阳离子构象、电荷载流子迁移率和宽带发射之间的关联。我们的研究表明，迁移率和宽带发射均强烈依赖于有机阳离子的分子构象有序性。有机阳离子的gauche缺陷和局部链扭曲是二维有机-无机钙钛矿面内迁移率降低和宽带发射的结构根源。层间距离和有机阳离子的构象有序性均影响面外迁移率。这项工作为优化二维有机-无机钙钛矿的光电特性时有机阳离子构象的分子水平理解提供了依据。
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