Phonon-Mediated Exciton Relaxation in Two-Dimensional Semiconductors: Selection Rules and Relaxation Pathways,The Journal of Physical Chemistry Letters

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Phonon-Mediated Exciton Relaxation in Two-Dimensional Semiconductors: Selection Rules and Relaxation Pathways
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2024-07-18 , DOI: 10.1021/acs.jpclett.4c01433
Xiao-Wei Zhang ₁ , Kaichen Xie ₂ , En-Ge Wang _{1,

3} , Xin-Zheng Li ₄ , Ting Cao ₂

Affiliation

Exciton–phonon coupling (ExPC) is crucial for energy relaxation in semiconductors, yet the first-principles calculation of such coupling remains challenging, especially for two-dimensional (2D) systems. Here, an accurate method for calculating ExPC is developed and applied in exciton relaxation problems in monolayer WSe₂. Considering the interplay between the exciton wave functions and electron–phonon coupling (EPC) matrix elements, we find that ExPC shows selection rules distinct from the ones of EPC. By employing the Wannier exciton model, we generalize these selection rules, which state that the angular quantum numbers of the exciton must match the winding numbers of the EPC matrix elements for the ExPC to be allowed. To verify our theory and method, we calculate intervalley exciton relaxation pathways, which agree well with a recent experiment.

中文翻译：

二维半导体中声子介导的激子弛豫：选择规则和弛豫路径

激子-声子耦合 (ExPC) 对于半导体中的能量弛豫至关重要，但这种耦合的第一性原理计算仍然具有挑战性，特别是对于二维 (2D) 系统。在此，开发了一种计算ExPC的精确方法并将其应用于单层WSe ₂中的激子弛豫问题。考虑到激子波函数和电子声子耦合（EPC）矩阵元素之间的相互作用，我们发现 ExPC 显示出与 EPC 不同的选择规则。通过采用 Wannier 激子模型，我们概括了这些选择规则，即激子的角量子数必须与 EPC 矩阵元素的绕数相匹配，才能允许 ExPC。为了验证我们的理论和方法，我们计算了层间激子弛豫路径，这与最近的实验非常吻合。

更新日期：2024-07-18

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