Memristors Based on Smectic Side-Chain Polymers with Lamellar Transport Channels

Polymeric materials have emerged as promising candidates for resistive random-access memory (RRAM) due to their low cost, flexibility, and solution processability. Among them, liquid crystalline polymers (LCPs) exhibit inherent hole and/or electron transport capabilities due to their self-assembling nature and have been utilized in diverse optoelectronic devices, yet their application in RRAM remains largely unexplored. In this work, smectic-phase and nematic-phase LCPs (PMMA-C6-X, X = CN, CF₃, NO₂) are synthesized using polymethyl methacrylate (PMMA) as the main chain, incorporating biphenyl rod-like LC moieties bearing a variety of polar terminal groups. These polymers are fully characterized and fabricated into sandwich-structured memristors (ITO/resistive layer/Al). In these LCPs, the π-conjugated segments establish directional charge transport channels through molecularly ordered alignment, enhancing resistive switching cyclic stability, while the flexible alkyl chains accommodate the requirements of flexible electronic devices. The investigation reveals that devices based on the obtained side chain LCPs exhibit stable resistive switching characteristics, including a low SET voltage (0.85 V), a high switching ratio (> 10³) and prolonged retention time (> 10⁴ s). This work demonstrates the potential of liquid crystal polymers for memory applications and provides a novel strategy for the design and fabrication of RRAM devices.