拉曼光谱
材料科学
相变
四方晶系
声子
钙钛矿(结构)
化学物理
正交晶系
密度泛函理论
分子动力学
凝聚态物理
光谱学
相(物质)
结晶学
晶体结构
光学
计算化学
化学
物理
有机化学
量子力学
作者
Alexander E. J. Hoffman,Rafikul Ali Saha,Sander Borgmans,P Puech,Tom Braeckevelt,Maarten B. J. Roeffaers,Julian A. Steele,Johan Hofkens,Véronique Van Speybroeck
出处
期刊:APL Materials
[American Institute of Physics]
日期:2023-04-01
卷期号:11 (4)
被引量:10
摘要
Metal-halide perovskites (MHPs) exhibit excellent properties for application in optoelectronic devices. The bottleneck for their incorporation is the lack of long-term stability such as degradation due to external conditions (heat, light, oxygen, moisture, and mechanical stress), but the occurrence of phase transitions also affects their performance. Structural phase transitions are often influenced by phonon modes. Hence, an insight into both the structure and lattice dynamics is vital to assess the potential of MHPs. In this study, GIWAXS and Raman spectroscopy are applied, supported by density functional theory calculations, to investigate the apparent manifestation of structural phase transitions in the MHP CsPbBr3. Macroscopically, CsPbBr3 undergoes phase transitions between a cubic (α), tetragonal (β), and orthorhombic (γ) phase with decreasing temperature. However, microscopically, it has been argued that only the γ phase exists, while the other phases exist as averages over length and time scales within distinct temperature ranges. Here, direct proof is provided for this conjecture by analyzing both theoretical diffraction patterns and the evolution of the tilting angle of the PbBr6 octahedra from molecular dynamics simulations. Moreover, sound agreement between experimental and theoretical Raman spectra allowed to identify the Raman active phonon modes and to investigate their frequency as a function of temperature. As such, this work increases the understanding of the structure and lattice dynamics of CsPbBr3 and similar MHPs.
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