Optical absorption of Fröhlich polaron in monolayer transition metal dichalcogenides

Abstract

We theoretically study the optical absorption of a Fröhlich polaron in monolayer transition metal dichalcogenides (TMDS) on different polar substrates using the Devreese-Huybrechts-Lemmens model, in which both the surface optical phonon modes induced by the polar substrate and the intrinsic longitudinal optical phonon modes have been taken into account. We find that the optical absorption occurs only as the energy of incident photon exceeds the energy of optical phonon. The behaviors of absorption are determined by the interplays between the strength of electron-optical phonon coupling and the energy of optical phonon. The amplitude of absorption can be tuned directly by the internal distance between TMDS and polar substrates. These theoretical results provide significant insight into the infrared absorption in two-dimensional materials.