Deterministic Fabrication and Quantum‐Well Modulation of Phase‐Pure 2D Perovskite Heterostructures for Encrypted Light Communication

Abstract Deterministic integration of phase‐pure Ruddlesden–Popper (RP) perovskites has great significance for realizing functional optoelectronic devices. However, precise fabrications of artificial perovskite heterostructures with pristine interfaces and rational design over electronic structure configurations remain a challenge. Here, the controllable synthesis of large‐area ultrathin single‐crystalline RP perovskite nanosheets and the deterministic fabrication of arbitrary 2D vertical perovskite heterostructures are reported. The 2D heterostructures exhibit intriguing dual‐peak emission phenomenon and dual‐band photoresponse characteristic. Importantly, the interlayer energy transfer behaviors from wide‐bandgap component to narrow‐bandgap component modulated by comprising quantum wells are thoroughly revealed. Functional nanoscale photodetectors are further constructed based on the 2D heterostructures. Moreover, by combining the modulated dual‐band photoresponse characteristic with double‐beam irradiation modes, and introducing an encryption algorithm mechanism, a light communication system with high security and reliability is achieved. This work can greatly promote the development of heterogeneous integration technologies of 2D perovskites, and could provide a competitive candidate for advanced integrated optoelectronics.