Hyperbranched polyimide with triazole core structure for nonvolatile resistive switching memory

Abstract

AbstractHyperbranched polyimides (HBPIs) possess a unique branched structure, which can make the lowest unoccupied molecular orbitals (LUMOs) degenerate and reduce the bandgap between the highest occupied molecular orbital (HOMO) and LUMO energy levels. The triazole group can facilitate the charge transfer process. Thus, a novel hyperbranched polyimide (HBPI‐TZA‐6FDA) has been prepared from new triazole derivative triamine monomer (TZA) and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) for memory device. The memory device with the structure ITO/HBPI‐TZA‐6FDA/Al exhibits a low‐threshold voltage of −2.2 V and a high ON/OFF current ratio of about 105. Meanwhile, the memory device shows nonvolatile write once read many times (WORM) type memory behavior and excellent stability with an operation time of 104 at a continuous applied voltage of −1 V. Optical, electrochemical experiments, and molecular simulation have been carried out to illustrate the memory performance. The memory performance is governed by the charge transfer between TZA and 6FDA units. The branched structure and triazole unit can reduce the band gap between HOMO and LUMO energy levels effectively, which is favorable for improving charge transfer and reducing threshold voltage. The HBPI‐TZA‐6FDA‐based memory device is favorable for memory device applications due to its relatively low‐power consumption and high‐operation stability.