Layer-engineered interlayer excitons

Photoluminescence (PL) from excitons serves as a powerful tool to characterize the optoelectronic property and band structure of semiconductors, especially for atomically thin two-dimensional transition metal dichalcogenide (TMD) materials. However, PL quenches quickly when the thickness of TMD materials increases from monolayer to a few layers, due to the change from direct to indirect band transition. Here, we show that PL can be recovered by engineering multilayer heterostructures, with the band transition reserved to be a direct type. We report emission from layer-engineered interlayer excitons from these multilayer heterostructures. Moreover, as desired for valley-tronics devices, the lifetime, valley polarization, and valley lifetime of the generated interlayer excitons can all be substantially improved as compared with that in the monolayer-monolayer heterostructure. Our results pave the way for controlling the properties of interlayer excitons by layer engineering.

Automated summary

By engineering multilayer heterostructures, photoluminescence can be recovered and the properties of generated interlayer excitons, including lifetime, valley polarization, and valley lifetime, can be substantially improved compared to monolayer-monolayer heterostructures.