Interlayer Exciton Diffusion in Strained MoSe₂-WSe₂ Heterobilayers

Interlayer excitons (IXs) in a vertically stacked heterobilayer of transition metal dichalcogenides (TMDs) have been widely studied in recent years due to the emergence of various collective phenomena. The formation of the long-lived IXs is attributed to the type-II band alignment and ultrafast charge transfer at the heterostructure interface. In this study, we explore intriguing characteristics of IXs formed in a strained MoSe₂-WSe₂ heterobilayer. Firstly, we outline a method for generating artificial moiré TMD superlattices through the application of uniaxial strain during the fabrication of the heterobilayer. Secondly, we investigate the optical properties of IXs, focusing on the polarization of the photoluminescence spectrum and the spatial map of diffusion images, both of which demonstrate the formation of a strained moiré heterostructure. Lastly, under the strained moiré potential landscape, we simulate the IX propagation by solving the diffusion equation, which is in good agreement with our experimental results.