Symmetric Azobenzene‐Type Small Molecules With Tunable Rigidity for High Performance Nonvolatile Organic Memory Devices

ABSTRACT

The rational design of functional molecular semiconductors is essential for advancing high‐performance organic memory technologies. Here, we report two symmetric donor–acceptor (D–A) azobenzene‐type small molecules, Cz‐Azo and DPA‐Azo, featuring tunable molecular rigidity and terminal electron‐donating substituents. Both molecules, as active layers in organic resistive memory devices, exhibit reliable nonvolatile bipolar resistive memory behavior with high ON/OFF current ratios, excellent cycling stability, and low operational voltages. Detailed characterizations reveal highly crystalline and densely packed molecular structures of Cz‐Azo and DPA‐Azo films, while theoretical calculations confirm that the rigid molecular backbone provides continuous channels for charge transfer (CT) and prevents conformational barriers in the excited state, leading to stable and reversible switching behaviors. Beyond their robust memory characteristics, the devices enable logic operations and exhibit neuromorphic computing potential, as demonstrated by the Cz‐Azo‐based device achieving 98.14% handwritten digit recognition accuracy on the Modified National Institute of Standards and Technology database (MNIST) dataset using a simulated multilayer perceptron. This study highlights molecular rigidity engineering and D‐A modulation in azobenzene‐based small molecules as an effective strategy for optimizing charge transport, storage stability, and device performance, providing new insights for the development of next‐generation high‐performance organic memory materials.