Solid‐Liquid Interfacial Engineered Large‐Area Two‐Dimensional Covalent Organic Framework Films

Abstract Constructing uniform covalent organic framework (COF) film on substrates for electronic devices is highly desirable. Here, a simple and mild strategy is developed to prepare them by polymerization on a solid‐liquid interface. The universality of the method is confirmed by the successful preparation of five COF films with different microstructures. These films have large lateral size, controllable thickness, and high crystalline quality. And COF patterns can also be directly achieved on substrates via hydrophilic and hydrophobic interface engineering, which is in favor of preparing device array. For application studies, the PyTTA‐TPA (PyTTA: 4,4′,4′′,4′′′‐(1,3,6,8‐Tetrakis(4‐aminophenyl)pyrene and TPA: terephthalaldehyde) COF film has a high photoresponsivity of 59.79 μA W −1 at 420 nm for photoelectrochemical (PEC) detection. When employed as an active material for optoelectronic synaptic devices for the first attempt, it shows excellent light‐stimulated synaptic plasticity properties such as short‐term plasticity (STP), long‐term plasticity (LTP), and the conversion of STP to LTP, which can be used to simulate biological synaptic functions.