Anharmonic electron-phonon coupling in ultrasoft and locally disordered perovskites
Anharmonic electron-phonon coupling in ultrasoft and locally disordered perovskites
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DOI：
10.1038/s41524-023-01089-2
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发表时间：
2023-02
影响因子：
9.7
通讯作者：
M. Zacharias;G. Volonakis;F. Giustino;J. Even
中科院分区：
文献类型：
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作者：
M. Zacharias;G. Volonakis;F. Giustino;J. Even
非和谐性和局部无序（多态性）在钙钛矿物理学中普遍存在，引发了在散射和光谱实验中观察到的各种现象。其中一些现象仍然缺乏基本原理的解释，因为迄今为止，还没有方法可以解释电子声子耦合中的不和谐性和无序性。在这里，依靠特殊的位移方法，我们开发了两者的统一处理方法，并证明当我们采用多态钙钛矿网络时，电子-声子耦合受到强烈影响。我们发现卤化物钙钛矿的多态性导致振动动力学远离理想的非相互作用声子图，并驱动相变温度附近带隙的逐渐变化。我们还澄清，由无序、自旋轨道耦合、高精度交换相关泛函和电子声子耦合引起的组合带隙校正都是必不可少的。我们的研究结果与实验一致，表明多态性是解决钙钛矿技术应用悬而未决的问题的关键。
Anharmonicity and local disorder (polymorphism) are ubiquitous in perovskite physics, inducing various phenomena observed in scattering and spectroscopy experiments. Several of these phenomena still lack interpretation from first principles since, hitherto, no approach is available to account for anharmonicity and disorder in electron–phonon couplings. Here, relying on the special displacement method, we develop a unified treatment of both and demonstrate that electron–phonon coupling is strongly influenced when we employ polymorphous perovskite networks. We uncover that polymorphism in halide perovskites leads to vibrational dynamics far from the ideal noninteracting phonon picture and drives the gradual change in their band gap around phase transition temperatures. We also clarify that combined band gap corrections arising from disorder, spin-orbit coupling, exchange–correlation functionals of high accuracy, and electron–phonon coupling are all essential. Our findings agree with experiments, suggesting that polymorphism is the key to address pending questions on perovskites’ technological applications.