Controllable Synthesis of an Island-like 3D CsPbBr₃ Nanocrystal/2D Graphene Nanosheet Heterojunction for Boosting Stability and Photoelectric Performance

Lead halide perovskite nanocrystals (NCs) have become a promising emerging material with significant potential in the field of micro-optoelectronic devices for their excellent optical properties. However, their inherent poor stability and low carrier separation efficiency have seriously hindered their potential applications under certain circumstances. Constructing 3D/2D semiconductor heterostructures with comprehensive advantages offers an effective way to improve the performance of all inorganic lead halide perovskites. In this study, we synthesized a heterostructure nanomaterial about an island-like 3D CsPbBr₃ NCs on 2D graphene nanosheets (GNS) using a chemical solution method with in situ controlled growth at room temperature. Using GNS as a substrate, we controlled the proportion of perovskite NCs and GNS, accurately regulated the area of isolated perovskite NCs on the surface of graphene, and regulated the photoelectric properties of the heterostructure nanomaterials. The carrier separation efficiency of the heterostructures was enhanced, and the optimal charge-transfer rate constant and energy-transfer efficiency were as high as 31.7 × 10⁷ s^-1 and 77.4% values, respectively. The 3D/2D perovskite/graphene heterostructures exhibited superior stability in polar solvents and at high temperatures. The heterostructure nanomaterials maintained good fluorescence stability at 160 °C and continue to emit even at 200 °C. Furthermore, the heterostructures also exhibited a steady photoelectric response, carrier transport, and cycle performance under similar extreme conditions, indicating broad applications for micro-optoelectronic devices.