Controlled fabrication of CsPbI2Br/transition metal dichalcogenide van der Waals heterostructure with fast carrier transfer process and interlayer exciton formation

Hybrid heterostructure formation between perovskite and transition metal dichalcogenides (TMDCs) provides an effective approach to alter the optical and electronic properties of pure monolayer TMDCs, thus is quite promising for photonic and photoelectronic applications. However, a feasible method to produce high quality perovskite/TMDCs heterostructures with controllable thickness and scalability is still lacked. Here, we demonstrate a non-destructive approach to construct the vertical heterostructures of CsPbI2Br/TMDC via dual-source thermal evaporation of thickness tunable CsPbI2Br films on monolayer TMDC. The type-II band alignment between CsPbI2Br and monolayer WSe2 or WS2 results in fast charge separation and quenching of photon emission intensity. The carrier transfer efficiency and rate of CsPbI2Br/WSe2 heterostructures can reach as high as 88% and 3.3 * 109 s−1, respectively. The ultra-fast and efficient charge transfer/separation shows that formation of hybrid heterostructure via deposition of perovskite on TMDC layers is of great significance for the outstanding optoelectronic device applications. More importantly, a broad low energy peak is observed below 174 K for the CsPbI2Br/TMDC heterostructures, which is probably induced by the interlayer exciton. Our findings provide a platform for exploring interlayer coupling and related physical processes in perovskite/TMDC heterostructures.