Temperature effect on optical spectra of monolayer molybdenum disulfide

Recently, measured optical absorption and photoluminescence spectra reveal substantial frequency shifts of both exciton and trion peaks as monolayer molybdenum disulfide, MoS2, is cooled from 363 K to 4 K. First-principles simulations using the GW-Bethe-Salpeter equation approach satisfactorily reproduce these frequency shifts by incorporating the thermal expansion effect. Studying these temperature effects in monolayer MoS2 is crucial for rectifying the results of available experiments with the previous predictions of zero-temperature-limit simulations. Moreover, our estimated thermal expansion coefficient of monolayer MoS2 is less than that of bulk counterpart by tracking the frequency shifts of the exciton peaks in optical spectra. This may serve as a convenient way to estimate thermal expansion coefficients of general two-dimensional chalcogenides.