HOMO-controlled donor-acceptor contained polyimide for nonvolatile resistive memory device

Molecular orbital energy level plays a vital role in the storage performance of memory materials. Fixing LUMO levels, reasonable regulation of HOMO level can effectively optimize the memory behaviors of storage devices. Therefore, two triazole-based donor-acceptor contained polyimides (TZMPDA-6FDA, TZAPDA-6FDA) with similar LUMO levels but different HOMO levels are designed and synthesized by introducing the pendant groups with different electron-donating ability. The LUMO levels of TZMPDA-6FDA and TZAPDA-6FDA are-1.98 and 1.99 eV, respectively. In comparison with TZMPDA-6FDA, the HOMO level of TZAPDA-6FDA increased from 5.32 to -5.23 eV due to the stronger electron-donating ability of diethylamino group than methoxy group. The increased HOMO level can reduce the energy barriers for charge carriers injection and migration, and thus effectively decrease the threshold voltage of memory devices from -2.4 to-1.8 V. The high-lying HOMO levels can facilitate the intraand inter-molecular charge transfer, which benefit to optimize the performance of the memory device.