Phonon Screening of Excitons in Semiconductors: Halide Perovskites and Beyond
Phonon Screening of Excitons in Semiconductors: Halide Perovskites and Beyond
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DOI：
10.1103/physrevlett.127.067401
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发表时间：
2021-08-05
影响因子：
8.6
通讯作者：
Neaton, Jeffrey B.
中科院分区：
文献类型：
--
作者：
Filip, Marina R.;Haber, Jonah B.;Neaton, Jeffrey B.
从头算Bethe-Salpeter方程（BSE）方法是研究材料中激子的一种既定方法，通常在仅捕获电子静态屏蔽的限制下求解。在这里，我们推广这个框架，包括动力学屏蔽声子在最低阶的电子-声子相互作用。我们将这种广义BSE方法应用于一系列无机卤化铅钙钛矿CsPbX 3，其中X = Cl，Br和I。我们发现，包括屏蔽声子显着降低了计算的激子结合能这些系统。通过推导出一个简单的表达式声子屏蔽效应，我们揭示了它们在半导体和绝缘体中的重要性的一般趋势，基于类氢激子模型。我们证明，在各向同性材料中的声子屏蔽校正的幅度可以可靠地预测使用四种材料的具体参数：减少有效质量，静态和光学介电常数，和频率的最强耦合的磁光声子模式。这个框架有助于阐明声子屏蔽的重要性及其与半导体中激子性质的关系。
The ab initio Bethe-Salpeter equation (BSE) approach, an established method for the study of excitons in materials, is typically solved in a limit where only static screening from electrons is captured. Here, we generalize this framework to include dynamical screening from phonons at lowest order in the electron-phonon interaction. We apply this generalized BSE approach to a series of inorganic lead halide perovskites, CsPbX3, with X = Cl, Br, and I. We find that inclusion of screening from phonons significantly reduces the computed exciton binding energies of these systems. By deriving a simple expression for phonon screening effects, we reveal general trends for their importance in semiconductors and insulators, based on a hydrogenic exciton model. We demonstrate that the magnitude of the phonon screening correction in isotropic materials can be reliably predicted using four material specific parameters: the reduced effective mass, static and optical dielectric constants, and frequency of the most strongly coupled longitudinal-optical phonon mode. This framework helps to elucidate the importance of phonon screening and its relation to excitonic properties in a broad class of semiconductors.