Fine-Tuning the Resistive Switching of Organic Write-Once-Read-Many Memory Devices Using Functionalized Pyridine...

A series of novel donor-bridge-acceptor (D-π-A) organic small molecules featuring pyridine-functionalized cores was designed, synthesized, and systematically investigated for application in nonvolatile resistive switching memory devices. The molecular framework was tailored via Pd-catalyzed Suzuki cross-coupling and Wittig-Horner condensation to integrate diverse electron-donating and electron-withdrawing functionalities. The molecular architecture integrated electron-rich units, such as tert-butylphenyl, methoxyphenyl, and dibenzofuran, with strong acceptors, such as cyano and nitroaryl groups, enable fine-tuning of electronic properties through structural asymmetry. Photophysical studies confirmed strong intramolecular charge transfer (ICT), and electrochemical analysis revealed narrow optical bandgaps of 3.10-3.20 eV. All materials exhibited stable binary memory behavior, with ON/OFF current ratios and retention times exceeding 10³ s. Notably, the dibenzofuran-nitrophenyl derivative exhibited superior performance, with a low threshold voltage of -1.11 V and an ON/OFF ratio of 10⁵. Density functional theory (DFT) and electrostatic potential analyses supported a charge transfer-assisted, charge trapping-enabled resistive-switching mechanism. Thin-film morphology and GI-XRD studies further indicated uniform film coverage and crystalline ordering. The tunable donor-acceptor substitution strategy provides valuable insights into molecular design principles for solution-processable, high-performance organic memory devices.