Self-Powered Organic Phototransistors with Asymmetrical van der Waals Stacking for Flexible Image Sensors

Abstract

Organic materials have drawn significant interest for next-generation advanced optoelectronic devices or systems owing to their extraordinary light absorption, intrinsic flexibility, and low-temperature, large-scale processability. While for high-performance organic photodetectors, their restricted carrier mobility, limited diffusion length, and high binding energy of Frenkel excitons have long been regarded as the major challenges. In this paper, we report a sensitive organic rubrene crystal/graphene heterostructure photodetector. Especially, using an asymmetrical van der Waals stacking configuration, we realized self-powered photon detection in such a graphene-based organic heterostructure device. Long-range exciton diffusion of the rubrene single crystal, the efficient exciton dissociation, and the ultrafast charge transfer near the heterointerface enabled several commendable performances, including the great responsivity of 8 × 10 5 A/W, specific detectivity of >10 12 Jones, and a fast response speed (ca. 20/70 μs). Encouragingly, the device exhibits excellent mechanical flexibility, remaining good conductivity, and stable light detection, even under harsh strain and after hundreds of cycles. Utilizing their outstanding photoresponse, we demonstrate fast-speed imaging applications on rigid and flexible substrates. Our work offers a practical strategy for developing high-performance, self-powered organic photodetectors for future wireless photon detection and high-speed imaging applications.