Ultrafast and Highly Mobile Photocarriers in Monolayer WSe2 Doped by α-RuCl3

We report an experimental investigation of photocarrier dynamics in a heterostructure formed by a WSe2 monolayer stacked on a multilayer α-RuCl3 flake. The samples were fabricated using mechanical exfoliation and dry transfer techniques. Photoluminescence measurements showed that the excitonic photoluminescence of WSe2 is quenched by more than 3 orders of magnitude upon contact with α-RuCl3. Transient absorption measurements revealed an ultrashort photocarrier lifetime of 0.5 ps in the heterostructure. Spatially resolved transient absorption microscopy measurements were employed to probe the transport properties of these photocarriers, resulting in a room-temperature diffusion coefficient of 370 cm2 s–1, which is higher than the exciton diffusion coefficients of most previously studied 2D semiconductors. These results suggest that α-RuCl3-doped WSe2 could be utilized in high-speed optoelectronic devices.