Renormalization of the exciton mass in monolayer transition metal dichalcogenides

The renormalization of the total effective mass of exciton in monolayer transition metal dichalcogenides (TMDC) on different polar substrates are investigated arising from the exciton-optical phonons coupling, in which both the intrinsic longitudinal optical phonon modes and surface optical phonon modes induced by the polar substrate are taken into account. We find that the total effective mass of exciton is enhanced obviously due to these coupling, depending on the cut-off wave vector of optical phonon modes, the polarizability of material and the internal distance between the monolayer TMDC and the polar substrate. The renormalization effect on the exciton mobility and the critical temperature of quantum degeneracy of the dilute exciton gas are discussed. Our theoretical results provide insight for the analysis of the exciton mass in experiments in two-dimensional materials.