Large photoelectric-gating effect of two-dimensional van-der-Waals organic/tungsten diselenide heterointerface

Photo- or photoelectric-gating modulation is a promising strategy for high-performance photodetectors, which amplifies photoresponsivity by long-lived trapped charges at the interface. However, the performance is normally limited by the uncontrollable trapping process. Here, we develop a large photoelectric-gating, which enhances interfacial charge trapping process by a van-der-Waals interface with an electric-gating tunable energy barrier in the band alignment. By synergy of photo-gating and electric-gating effects, responsivity and detectivity of 1,4-bis(4-methylstyryl)benzene/tungsten diselenide (WSe 2 ) increase by 25-fold and 3-fold to 3.6 × 10 6 A/W and 8.6 × 10 14 Jones. High-quality two-dimensional van-der-Waals interface is of great importance. Sufficient supply of gas-phase molecules in physical vapor deposition is pivotal to obtain such interface between organic crystal and WSe 2 . As an application, an electric-gating switchable photodetector has been developed, showing great potential of this strategy not only in high-performance photodetectors but also in new photoelectrical devices. Photodetectors: Large photoelectric-gating effect in p-MSB/WSe 2 heterostructures A heterostructure of 1,4-bis(4-methylstyryl)benzene (p-MSB) and WSe 2 possesses an electric-gating tunable barrier at the interface. A team led by Dacheng Wei at Fudan University developed a van der Waals heterostructure consisting of an organic p-MSB crystal epitaxially grown on WSe 2 , an atomically thin transition metal dichalcogenide. A large photoelectric-gating effect was found to occur thanks to the combination of photo-gating and electric-gating effects, leading to an enhancement of the interfacial charge trapping process. As a result of the tunable barrier, capable of trapping more photogenerated electrons at the interface, the electric-gating switchable p-MSB/WSe 2 photodetector showed a higher responsivity when compared to devices modulated by conventional photo-gating techniques. These findings extend the physical understanding of the growth mechanism of organic crystals on transition metal dichalcogenides, and open up promising avenues for high-performance photodetectors.