Strain‐Activated Stimulated Emission from Multilayer MoSe2 in a Narrow Operation Window

Herein, photoluminescence (PL) and fluorescence lifetime imaging (FLIM) in multilayer MoSe2 are studied. Strain‐activated stimulated emission via defect levels in multilayer MoSe2 under laser excitation is observed, for the first time in defects of transition metal dichalcogenides. The stimulated emission is indicated by a threshold behavior of PL emission intensity with respect to laser intensity, strong polarization effects, achieved population inversion with a difference in lifetimes of two competing excited states, and localization of the stimulated emission zone as observed in FLIM. The presented results not only demonstrate strain‐activated stimulated emission and highlight the necessity of strain engineering in tailoring 2D layered materials for optoelectronic applications, but also shed light on the design of stimulated emission in transition metal dichalcogenide's defects to tailor for potential single‐photon emission behavior. This work reports stimulated emissions with features of threshold behavior of photoluminescence intensity with respect to laser excitation intensity, strong polarization effects, population inversion with a difference in lifetimes of two competing excited states, and localization of the stimulated emission zone as observed in fluorescence lifetime mapping in strained multilayer MoSe2.