Graphene-Interlayered Sandwich Heterostructures with Step-like Band Alignment for Enhanced Electronic Transport and Fast Photodetection.

The integration of two-dimensional materials into van der Waals heterostructures provides a powerful strategy for developing advanced optoelectronic devices. Nevertheless, efficient photodetection remains challenging, as it demands precise management of carrier dynamics in terms of effective dissociation of excitons and rapid transport of charges across the heterointerfaces. Herein, we demonstrate a sandwich-type InSe/graphene/MoTe2 heterostructure by employing a band structure engineering strategy. The graphene interlayer establishes a step-like band alignment, thus promoting efficient separation and transport of photogenerated carriers at the interfaces. Consequently, alongside a prominent improvement in carrier mobility, the InSe/graphene/MoTe2 photodetector exhibits a fast photoresponse with a rise/fall time of 2.87/3.68 μs, 2 orders of magnitude faster than its bilayer InSe/MoTe2 counterpart. Furthermore, the InSe/graphene/MoTe2 photodetector is employed in imaging and optical signal encoding/decoding, demonstrating its potential for low-error-rate data transmission in the near-infrared region. This study opens new avenues for developing high-performance optoelectronic devices through interlayer band alignment engineering.