Temperature dependence of the excitonic spectra of monolayer transition metal dichalcogenides

Abstract

We theoretically study the temperature dependence of the excitonic spectra of monolayer transition metal dichalcogenides using the O′Donnell equation, E_g\left(T\right)=E_g\left(0\right)-S\langle \hslash w\rangle [\coth \frac{\langle \hslash w\rangle }{2k_{B}T}-1]. We develop a theoretical model for the quantitative estimation of the Huang–Rhys factor S and average phonon energy \langle \hslash w\rangle based on exciton coupling with longitudinal optical and acoustic phonons in the Fröhlich and deformation potential mechanisms, respectively. We present reasonable explanations for the fitted values of the Huang–Rhys factor and average phonon energy adopted in experiments. Comparison with experimental results reveals that the temperature dependence of the peak position in the excitonic spectra can be well reproduced by modulating the polarization parameter and deformation potential constant.

Keywords

transition metal dichalcogenides / exciton / Huang–Rhys factor

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