Linkage effects of triphenylamine-based aromatic polymer electrets on electrical memory performance

Abstract

Here, we use polyimide (PI), polyether (PE) and polyester (PET) with diphenyl sulfonyl (S) moieties combined with triphenylamine (TPA) units to obtain three polymer electrets, TPA-PIS, TPA-PES, and TPA-PETS, respectively. The pentacene-based organic field effect transistor (OFET) memories with the charge-trapping polymer electrets layer were examined. The variation in linkages in the polymer backbone noticeably influences the energy structures and molecular polarity, and thus their memory properties were systematically characterized and compared. Volatile memory characteristics can be observed for all three polymer electrets-based memories. Among these, the TPA-PIS and TPA-PETS electret OFET memory devices exhibit ambipolar trapping behavior capable of storing holes and electrons, with a memory window (MW) of 32.4 ± 1.2 V and 21.7 ± 1.0 V, respectively, and a memory ratio of 104∼106. Importantly, programming/erasing switching endurance for at least 100 cycles is achieved, allowing for tri-state memory storage. However, hole-only unipolar trapping of OFETs memory with the TPA-PES electret presents relatively slower charge detrapping phenomena and longer retention time ability due to the higher molecular dipole moment. Our comparative study demonstrates the important role of the linkage effect in aromatic polymers for developing polymer electret-based OFET memories.