论文标题
第一原则超快激发激素动力学和时间域光谱：Dark-exciton中介山谷去极化单层WSE $ _2 $
First-Principles Ultrafast Exciton Dynamics and Time-Domain Spectroscopies: Dark-Exciton Mediated Valley Depolarization in Monolayer WSe$_2$
论文作者
论文摘要
将第一原理电子波（$ e $ -ph）与Boltzmann方程相结合的计算使超快载体和声子动力学的研究。但是，在库仑筛查弱的材料中，电子和孔形成绑定的激子及其散射过程变得相关，从而构成了对非平衡物理学建模的额外挑战。在这里，我们使用$ ab〜InitiO $ INTIO $ INTIOM-PHONON（ex-PH）相互作用以及Ickitonic Boltzmann方程来显示超快激发动力学和相关时间域光谱的计算。从非平衡的激子种群开始，我们开发了考虑到电子孔相关性的时域吸收和光发射光谱的模拟。我们使用这种方法来研究单层WSE $ _2 $，我们的计算预测了激子松弛和山谷去极化的次秒时间尺度，并揭示了中间深色激子的关键作用。这项工作中介绍的方法可以定量描述具有强烈结合激子的材料中的非平衡动力学和超快光谱。
Calculations combining first-principles electron-phonon ($e$-ph) interactions with the Boltzmann equation enable studies of ultrafast carrier and phonon dynamics. However, in materials with weak Coulomb screening, electrons and holes form bound excitons and their scattering processes become correlated, posing additional challenges for modeling nonequilibrium physics. Here we show calculations of ultrafast exciton dynamics and related time-domain spectroscopies using $ab~initio$ exciton-phonon (ex-ph) interactions together with an excitonic Boltzmann equation. Starting from the nonequilibrium exciton populations, we develop simulations of time-domain absorption and photoemission spectra that take into account electron-hole correlations. We use this method to study monolayer WSe$_2$, where our calculations predict sub-picosecond timescales for exciton relaxation and valley depolarization and reveal the key role of intermediate dark excitons. The approach introduced in this work enables a quantitative description of nonequilibrium dynamics and ultrafast spectroscopies in materials with strongly bound excitons.
