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arXiv · 2212.08451

Exciton lifetime and optical linewidth profile via exciton-phonon interactions: Theory and first-principles calculations for monolayer MoS$_2$

Y. -H. Chan·Jonah B. Haber·Mit H. Naik·J. B. Neaton·Diana Y. Qiu·Felipe H. da Jornada·Steven G. Louie
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Abstract

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.

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Y. -H. Chan, Jonah B. Haber, Mit H. Naik, J. B. Neaton, Diana Y. Qiu, Felipe H. da Jornada, Steven G. Louie. 2022-12-16. Exciton lifetime and optical linewidth profile via exciton-phonon interactions: Theory and first-principles calculations for monolayer MoS$_2$. https://doi.org/10.1021/acs.nanolett.3c00732

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