论文标题
激子寿命和光学线宽曲线通过激子 - phonon互动：单层MOS $ _2 $的理论和第一原理计算
Exciton lifetime and optical linewidth profile via exciton-phonon interactions: Theory and first-principles calculations for monolayer MoS$_2$
论文作者
论文摘要
激子动力学决定了光伏和光电设备中光激发载体的演变。但是，由于电子 - 音波和许多电子相互作用的存在，解释其实验签名是一个具有挑战性的理论问题。我们在这里开发并应用了一种第一原理方法，用于单层MOS2中的激子 - phonon耦合导致的激子动力学，并揭示了由于激子的内部自旋结构而导致的激子 - phonon耦合的高度选择性，这导致了最漫长的寿命，使最低的能量呈现出较低的能量。此外，我们表明，正如Toyozawa和Hopfield提出的那样，光子和声子在相等的基础上进行处理，需要严格的光吸收过程，并需要使用光子和声子。到目前为止，这种治疗方法在第一原理研究中被忽略了，从而引起了偏双型激子 - phonon耦合矩阵元素，这对于描述脱位机制至关重要，并与实验相当一致。
Exciton dynamics dictate the evolution of photoexcited carriers in photovoltaic and optoelectronic devices. However, interpreting their experimental signatures is a challenging theoretical problem due to the presence of both electron-phonon and many-electron interactions. We develop and apply here a first-principles approach to exciton dynamics resulting from exciton-phonon coupling in monolayer MoS2 and reveal the highly selective nature of exciton-phonon coupling due to the internal spin structure of excitons, which leads to a surprisingly long lifetime of the lowest energy bright A exciton. Moreover, we show that optical absorption processes rigorously require a second-order perturbation theory approach, with photon and phonon treated on an equal footing, as proposed by Toyozawa and Hopfield. Such a treatment, thus far neglected in first-principles studies, gives rise to off-diagonal exciton-phonon coupling matrix elements, which are critical for the description of dephasing mechanisms, and yields exciton linewidths in excellent agreement with experiment.
