A low-cost broadband photodetector based on CsPbBr3quantum dots/transfer-free eco-friendly graphene heterostructures for fast photoresponse.

We have successfully demonstrated CsPbBr₃perovskite quantum dots (QDs)/transfer-free eco-friendly (TFEF) graphene heterostructures with broadband and fast photoresponse. At first, the TFEF graphene is grown directly on the SiO₂/Si substrates in an atmospheric pressure chemical vapor deposition (APCVD) system with the copper-foil wrapping methods and camphor precursors. Raman mapping image (15 × 15μm²) showed TFEF graphene with high coverage across the surface (∼65% single-layer graphene, ∼15% bilayer graphene, and ∼20% multilayer graphene). After that, CsPbBr₃QDs were synthesized and then spin-coated on the TFEF graphene surface to form heterostructures. Compared to pure CsPbBr₃QD-based photodetectors (PDs), CsPbBr₃QDs/TFEF graphene-based PDs show a higher photo-to-dark current ratio of ∼7.2 at 2 V white light illumination (112 mW cm^-2). Furthermore, the CsPbBr₃QDs/TFEF graphene-based PDs show a broadband photoresponse range from ultraviolet to near-infrared with a peak responsivity reaching up to 32 mA W^-1, a high detectivity (2.2 × 10¹⁰cm·Hz^1/2/W) and fast operation speed (rise/fall time: ∼7/∼ 14 ms). This study opens avenues to develop low-cost and rapid fabrication processes of perovskite/2D nanomaterial-based PDs for fast optical communication, image capture, and flame detection applications.