Realizing Ultrahigh Detectivity and Fast Respond Speed Self-Powered Photodetectors Based on PdSe ₂ /Gr/InSe van der Waals Heterojunction with Graphene Interlayer

Two-dimensional semiconductor materials serve as a competitive candidate for the fabrication of next-generation microelectronic devices with high performance and integration, and the 2D van der Waals heterojunction is proposed to achieve self-powered photodetection. As the device performance is more sensitive to the interface at the atomic scale, it can be enhanced by inserting a graphene interlayer into heterostructures to improve interface quality. In this work, a heterostructure photodetector with a graphene interlayer based on the PdSe₂/Gr/InSe 2D van der Waals heterojunction was designed. The device showed excellent self-powered photoelectric performance responding to a wide range of light (405-980 nm) with responsivity and detectivity reaching 937.6 mA/W and 4.6 × 10¹² Jones, respectively. It also demonstrated a fast response speed of 34/39 μs and high light on/off ratio of 6.99 × 10⁵. Finally, the device was utilized in an imaging system. This study introduced an effective way of inserting graphene into heterostructures to achieve high-performance, fast-response photodetectors.