Visualizing Exciton Funneling in the Nanowrinkles of Twisted Bilayer MoS2 Using Tip-Enhanced Optical Spectroscopy

In transferred twisted bilayer (tBL) two-dimensional transition-metal dichalcogenides (TMDs), large strain in the nanowrinkles can induce strong deforming potential, resulting in strong localized excitonic behavior. Probing localized interlayer exciton behavior challenges the spatial resolution and sensitivity of conventional analytical tools. Herein, we have applied tip-enhanced photoluminescence (TEPL) nanoscopy for investigation of nanowrinkles in tBL MoS2. The localization of interlayer and intralayer excitons at the nanowrinkles was clearly revealed in the hyperspectral TEPL image of tBL MoS2. Using high-resolution TEPL data, the excitonic potential at the nanowrinkles was experimentally determined to be 8.6 +/- 1.9 meV. Furthermore, the TEPL experimental results were corroborated by numerical simulations based on the exciton diffusion theory. The novel insights into the excitonic behavior of nanowrinkles in t2L MoS2 obtained in this work deepen our understanding of the optoelectronic behavior in t2L TMD materials.