CVD growth of perovskite/graphene films for high-performance flexible image sensor

Hybrid perovskite possesses excellent photoelectric properties, including large light-absorption capacity and high carrier mobility, and is an ideal light-absorbing material for photoelectric devices. The grain size and compactness of hybrid perovskite are key factors affecting the performance of photoelectric devices. The photocurrent and photoresponsivity of these devices are relatively low because of the rapidly recombined photoexcited electron-hole pairs in hybrid perovskite. Herein, we develop a facile two-step chemical vapor deposition (CVD) method to synthesize a high-quality van der Waals (vdWs) MAPbI₃/graphene heterostructure for high-performance image sensor. We introduced inorganic sources (PbI₂) to vdWs epitaxially grown PbI₂ film on a seamless graphene monolayer film template through CVD. Methylammonium iodide (MAI) was then reintroduced to prepare the vdWs MAPbI₃/graphene heterostructure. The MAPbI₃ layer is composed of densely packed, large-size grains and displays a smooth surface. High photoresponsivity of 10⁷ A/W is achieved in the corresponding photodetector. Inspired by the human visual system, we designed a flexible photodetector array containing (24 × 24) pixels, achieving perfect image recognition and color discrimination. Our study may greatly facilitate the construction of high-performance optoelectronic devices in artificial retina, biomedical imaging, remote sensing, and optical communication.