All-Inorganic Perovskite Nanosheet Fabrication under Synergistic Effect for Integrated Optoelectronics with Strong Light–Matter Interactions

All-inorganic perovskites have emerged in the field of optoelectronic devices for their excellent light absorption and energy conversion efficiencies, as well as their superior stability compared to organic–inorganic perovskites. The two-dimensional (2D) all-inorganic perovskites have a higher exciton binding energy and carrier recombination efficiency than their bulk counterparts due to the quantum confinement effect, which indicts high strong light–matter interactions and is suitable for special integrated optoelectronics such as a micro laser or quick-response photodetector. However, it is difficult to fabricate a 2D large-sized sample with high crystal quality due to the nonlayered structure, which limits its further research and practical application. In this work, based on an atmospheric pressure chemical vapor deposition strategy combining a space-confined method and van der Waals epitaxy, the synergistic effect of these two techniques results in large-sized ultrathin all-inorganic CsPbI3 perovskite nanosheets for which the lateral dimension can exceed 50 μm while the smallest thickness can reach 3 nm. The high crystal quality of the square-like samples has been confirmed by a microstructure characterization, while the corresponding performances like long carrier life (360 ns), high resistivity, and good stability were also verified, implying great promise for their applications in high-performance integrated optoelectronics. This method may pave the way for a uniform fabrication of other 2D nonlayered materials as well.