Efficient charge transfer in WS2/WxMo1−xS2 heterostructure empowered by energy level hybridization

Photoinduced charge transfer (CT) is decisive to the efficiency and speed of photoelectric conversion in two-dimensional (2D) van der Waals (vdWs) heterostructures. Generally, CT rate enhancement is realized by increasing the band offset (BO). In this study, we propose that a fast and efficient CT can be realized via strong hybridization of energy levels in 2D vdWs heterostructures with minimal BO. First-principles calculations reveal that the smallest energy difference between conduction-band edges and minimal BO in the WS2/WxMo1−xS2 (x = 0.78) heterostructure yields the strong hybridization of energy levels and then results in ultrafast CT (2.7 ps). Experimental results agree with theoretical calculations. The photoluminescence of WS2 is quenched in the WS2/WxMo1−xS2 (x = 0.78) heterostructure, attributable to the strong hybridization-induced fast and efficient CT. This study provides insights into the mechanism of CT in heterostructures and offers new strategies to create superior optoelectronic devices with fast and efficient photoelectric conversion.