Near-Infrared Photoresponse Driven by Strong Interlayer Transition in 2D MoSe₂/WSe₂ van der Waals Heterostructures: Implications for Broadband Photodetectors

Bandgap engineering of transition metal dichalcogenides (TMDCs) opens up opportunities to design broadband photodetectors via interlayer transition in type-II van der Waals (vdWs) heterostructures. However, the photoresponse related to interlayer coupling remains elusive, because of the limited efficiency of interlayer electron-hole generation and separation. Herein, we report the near-infrared optoelectronic response driven by the interlayer transition in MoSe₂/WSe₂ bilayer-bilayer vdWs heterostructure grown by one-pot chemical vapor deposition (CVD). It is found that the interlayer distance of the MoSe₂ bilayer and WSe₂ bilayer approximately reaches a single atomic layer, which enhances the strength of interlayer coupling. A substantial build-in potential in MoSe₂/WSe₂ heterostructure leads to rapid separation of photogenerated carriers. Moreover, this MoSe₂/WSe₂ bilayer-bilayer heterostructure exhibits high optoelectronic performance from the visible to near-infrared spectrum, obtaining a near-infrared photoresponse time of 38 μs at 940 nm. Our work may provoke further exploration of interlayer transition in type-II TMDCs heterostructures and their applications in broadband photodetectors.