Liu Quan, Zhao Caibin, Tian Guanghui, Ge Hongguang
Shaanxi Province Key Laboratory of Catalytic Foundation and Applications, School of Chemical and Environmental Science, Shaanxi University of Technology Hanzhong 723001 China
RSC Adv. 2018 Jan 3;8(2):805-811. doi: 10.1039/c7ra11932a. eCollection 2018 Jan 2.
Two conjugated small molecules with different molecular conjugation, 4',4''-(diazene-1,2-diyl)bis(2',3',5',6'-tetrafluoro-,-diphenyl-[1,1'-biphenyl]-4-amine) (TPA-azo-TPA) and 4,4'-(perfluorophenazine-2,7-diyl)bis(,-diphenylaniline) (TPA-ph-TPA), in which the electron donor triphenylamine moiety is bridged using different electron-accepting azobenzene or phenazine blocks, were designed and synthesized. The TPA-ph-TPA molecule with a larger conjugation acceptor regularly formed a nanocrystalline film and the as-fabricated memory devices exhibited outstanding non-volatile write once read many (WORM) memory effects with an ON/OFF ratio ten times higher than that of TPA-azo-TPA. Using theoretical calculations, it was speculated that the memory performance is a result of an electric field induced charge transfer effect and the enhanced device performance of the acceptor molecular conjugation is because of the presence of a strong charge transfer effect. The experimental findings suggest that the strategy of molecular conjugation may promote the performance of small molecule-based organic electronic memory devices by an enhanced a strong charge transfer effect.
设计并合成了两种具有不同分子共轭结构的共轭小分子，4',4''-(重氮-1,2-二基)双(2',3',5',6'-四氟-,-二苯基-[1,1'-联苯]-4-胺)(TPA-偶氮-TPA)和4,4'-(全氟吩嗪-2,7-二基)双(,-二苯基苯胺)(TPA-菲-TPA)，其中电子给体三苯胺部分通过不同的电子受体偶氮苯或吩嗪嵌段连接。具有较大共轭受体的TPA-菲-TPA分子规则地形成了纳米晶薄膜，所制备的存储器件表现出优异的非易失性一次写入多次读取(WORM)存储效应，其开/关比是TPA-偶氮-TPA的十倍。通过理论计算推测，存储性能是电场诱导电荷转移效应的结果，受体分子共轭增强的器件性能是由于存在强电荷转移效应。实验结果表明，分子共轭策略可以通过增强强电荷转移效应来提升基于小分子的有机电子存储器件的性能。
