Exciton-phonon coupling in mono- and bilayer MoTe2

Abstract

We study the temperature-dependent photoluminescence of monolayer and bilayer molybdenum ditelluride in the temperature range between 5 K and room temperature. We disentangle the effects of interactions of excitons with acoustic and optical phonons and show that molybdenum ditelluride excitons have an unusually small coupling with acoustical phonons. This observation, together with the large luminescence yield which can be obtained from the bilayer, puts forward molybdenum ditelluride as a robust and bright light source in the near infrared range. The scaling of luminescence wavelength and linewidth of the molybdenum ditelluride bilayer differs from the observations in the monolayer by effects that can be traced to symmetry and wellwidth. This suggests a similar band alignment of mono- and bilayer, in contrast to other transition metal dichalcogenides.