Nonlinear Photoluminescence in Atomically Thin Layered WSe2 Arising from Diffusion-Assisted Exciton-Exciton Annihilation

摘要

We studied multi-exciton dynamics in monolayer WSe2 using nonlinearphotoluminescence (PL) spectroscopy and Monte Carlo simulations. We observedstrong nonlinear saturation behavior of exciton PL with increasing excitationpower density, and long-distance exciton diffusion reaching severalmicrometers. We demonstrated that the diffusion-assisted exciton-excitonannihilation model accounts for the observed nonlinear PL behavior. Thelong-distance exciton diffusion and subsequent efficient exciton-excitonannihilation process determined the unusual multi-exciton dynamics inatomically thin layered transition metal dichalcogenides.