Engineering Conjugated Bridges in TPE-BT-Based Donor–Acceptor Molecules for Optimized Resistive Random Access Memory

Four donor-acceptor (D-A) type organic small molecules, namely, 4,7-bis(4-(1,2,2-triphenylvinyl)phenyl)benzo[<i>c</i>][1,2,5]thiadiazole(TPE-BT), 4,7-bis((4-(1,2,2-triphenylvinyl)phenyl)ethynyl)benzo[<i>c</i>][1,2,5]thiadiazole(TPE-<i>ynl</i>-BT), 4,7-bis(5-(4-(1,2,2-triphenylvinyl)phenyl)thiophen-2-yl)benzo[<i>c</i>][1,2,5]thiadiazole (TPE-<i>Th</i>-BT), and 4,7-bis((5-(4-(1,2,2-triphenylvinyl)phenyl)thiophen-2yl)ethynyl)benzo[<i>c</i>][1,2,5]thiadiazole(TPE-<i>Th</i>-<i>ynl</i>-BT), each incorporating unique conjugated bridges, are designed, synthesized, and integrated into resistive random access memory (RRAM) devices. Current-voltage (<i>I-V</i>) measurements indicate that the TPE-BT, TPE-<i>ynl</i>-BT and TPE-<i>Th</i>-BT based devices exhibit write-once-read-many-times (WORM) characteristics, while TPE<i>-Th-yn</i>l-BT based devices show a stable flash-type switching behavior. In comparison to TPE-BT, the memory devices constructed with TPE-<i>ynl</i>-BT, TPE-<i>Th</i>-BT and TPE-<i>Th</i>-<i>ynl</i>-BT, which include additional conjugated bridges, exhibit nonvolatile memory capabilities with reduced threshold voltages, higher <i>I</i>_ON/<i>I</i>_OFF (10⁴:1), enhanced stability, and improved reproducibility. The photophysical, electrochemical analyses, and X-ray diffraction (XRD) results reveal that incorporating conjugated bridges within molecular structures can enhance data storage performance while reducing power consumption. Our findings demonstrate that these conjugated bridges play a crucial role in optimizing electrical memory characteristics and resistive switching behavior. Moreover, the device fabricated with TPE-<i>Th-ynl</i>-BT is effectively applied to logic gate circuits and American Standard Code for Information Interchange (ASCII) art function, highlighting its promising potential as a smart sensor within artificial intelligence (AI) networks.