A Synaptic Device Based on a Coordinated-Metal-Synergetic Covalent Organic Framework for Highly Efficient Neuromorphic Application

Two-dimensional covalent organic frameworks (2D COFs) have emerged as promising candidates for memristor applications due to their large surface area, rich active sites, and regular framework structure. However, because of their poor intrinsic conductivity, most 2D memristive COFs rely on the conductive filaments (CFs) mechanism, which are prone to generating excessive and disorderly CF growth, posing a challenge to the stability of device performance. To address this issue, we precisely incorporate metal atoms into the framework and synthesize a coordinated metal-containing COF (CMC-COF) as an efficient memristive material. This strategy greatly enhances the conductivity of 2D COF and achieves stable multistate switching based on its intrinsic stepwise charge transfer (ISCT) effect rather than random CFs. The biosynaptic mimicking behavior of devices affords a high CNN-based digital recognition accuracy of over 97%. Furthermore, a multicolor 2D Quick Response Code (QR code) is developed for the construction of the brain-inspired cognitive system, enabling more convenient item coding and information encryption. This work sets an example for developing highly feasible metal-containing nanocrystalline COF materials to implement neuromorphic computing and intelligent cognitive applications.