Manipulating single-photon emitter radiative lifetime in transition-metal dichalcogenides through Forster resonance energy transfer to graphene

Structural defects can crucially impact the optical response of monolayer (ML) thick materials as they are considered as efficient trapping sites for excitons. These trapped excitons are located below the free exciton emission. This phenomenon can give rise to a new type of emitters, known as single-photon emitters (SPEs). In this paper we outline the criteria, within our framework, by which single-photon emissions can be enabled in two-dimensional materials and we explore how these criteria can be fulfilled in atomically thin transition-metal dichalcogenides (TMD). In particular, we model the defects effect, in accordance with the most common experimental realisations, on the spatial autocorrelation function of the random disorder potential. Moreover, we provide a way to control the radiative lifetime of these emissions by a hybrid heterostructrue of a ML TMD with a graphene sheet separated by a dielectric material with a controlled thickness, which enables Forster resonance energy transfer process. Our paper predicts that the corresponding SPEs quenched radiative lifetime, which depends strongly on the dielectric environment, will be in the picosecond range. The range of our calculated exciton radiative lifetime in graphene-TMD heterostructure is consistent with that found in recent measurements.

Automated summary

Structural defects can significantly affect the optical response of monolayer materials and lead to the formation of single-photon emitters (SPEs). This study outlines the criteria for enabling single-photon emissions in two-dimensional materials and explores how they can be achieved in atomically thin transition-metal dichalcogenides (TMD). By modeling the effect of defects and using hybrid heterostructures, it is possible to control the radiative lifetime of these emissions.