Exploring the potential of malononitrile functionalized donor–acceptor systems for non-volatile memory device applications

Abstract

A novel series of D-bridge-A type organic small molecules has been designed, synthesized, and evaluated for non-volatile resistive switching write-once read-many (WORM) memory application. This study explores structure–property relationships by coupling electron-deficient malononitrile units with donors such as dibenzofuran, dibenzothiophene, and triphenylamine. Photophysical investigations revealed significant intramolecular charge transfer interaction, while electrochemical analyses demonstrated optimal band gaps ranging from 2.20 to 3.10 eV. All synthesized compounds exhibited robust, non-volatile, resistive switching memory capabilities, with ON/OFF ratios spanning 10² to 10³. The lowest recorded threshold voltage was −1.25 V, and devices demonstrated substantial stability with retention times of 10³ s. Notably, triphenylamine-based compounds displayed superior memory performance compared to their counterparts. The solubility of the compounds in common organic solvents suggests that they are viable for cheap fabrication techniques. Density functional theory calculations were used to visualize the key molecular orbitals and support the proposed mechanisms for resistive switching. The strategic implementation of equipotential donors and acceptors is highly desirable. This well-rounded approach guarantees optimal performance and fosters broader applicability of these devices.