  The multimode Brownian oscillator model is employed to simulate the emission
spectra of transition metal dichalcogenide monolayers. Good agreement is
obtained between measured and simulated photoluminescence spectra of WSe2, WS2,
MoSe2 and MoS2 at various temperatures. The Huang-Rhys factor extracted from
the model can be associated with that from the modified semi-empirical Varshni
equation at high temperatures. Individual mechanisms leading to the unique
temperature-dependent emission spectra of those TMDs are validated by the MBO
fitting, while it is in turn confirmed that the MBO analysis is an effective
method for studying the optical properties of TMD monolayers. Parameters
extractd from the MBO fitting can be used to explore exciton-photon-phonon
dynamics of TMDs in a more comprehensive model.
