Synthesis and memory characteristics of highly organo-soluble polyimides bearing a noncoplanar twisted biphenyl unit containing aromatic side-chain groups
作者:Yueqin Li、Huihua Xu、Xian Tao、Kejia Qian、Shuang Fu、Yingzhong Shen、Shijin Ding
DOI:10.1039/c0jm02547j
日期:——
Two novel 3′,4′,5′-trifluorobiphenyl-based aromatic polyimide monomers, 2,2′-bis[4′-(3′′,4′′,5′′-trifluorophenyl)phenyl]-4,4′-biphenyl diamine (BTFBPD) and 2,2′-bis[4′-(3′′,4′′,5′′-trifluorophenyl)phenyl]-4,4′,5,5′-biphenyltetracarboxylic dianhydride (BTFBPDA) were synthesized. Two fluorinated polyimides (PIs), PI(BTFBPD-DPBPDA) and PI(BTFBPD-BTFBPDA) were prepared via a two-step procedure using BTFBPD reacting with 2,2′-diphenyl-4,4′,5,5′-biphenyltetracarboxylic dianhydride (DPBPDA) and BTFBPDA, respectively. BTFBPD was characterized with single crystal X-ray diffraction analysis and the geometric parameters showed the noncoplanar twisted character. PIs exhibited highly organo-solubility and thermal stability. The PI films sandwiched between an indium-tin oxide(ITO) bottom electrode and Al top electrode exhibited two accessible conductivity states and can be switched from the low-conductivity to the high-conductivity. The memory devices with the configuration of Al/PI(BTFBPD-DPBPDA)/ITO exhibited a flash type memory capability, whereas the Al/PI(BTFBPD-BTFBPDA)/ITO presented a write once read many times (WORM) memory capability. The fabricated devices showed low turn-on threshold voltages of −1.3 V (PI(BTFBPD-DPBPDA)) and −1.7 V (PI(BTFBPD-BTFBPDA)) and both ON/OFF current ratios on the order of 103 to 104.
两种新型 3′,4′,5′-三氟联苯基芳香族聚酰亚胺单体,2,2′-双[4′-(3′′,4′′,5′′-三氟苯基)苯基]-4、4′-联苯二胺(BTFBPD)和 2,2′-双[4′-(3′′′,4′′,5′′-三氟苯基)苯基]-4,4′,5,5′-联苯四羧酸二酐(BTFBPDA)的合成。利用 BTFBPD 与 2,2′-二苯基-4,4′,5,5′-联苯四羧酸二酐 (DPBPDA) 和 BTFBPDA 反应,通过两步法制备了两种氟化聚酰亚胺 (PI):PI(BTFBPD-DPBPDA) 和 PI(BTFBPD-BTFBPDA)。用单晶 X 射线衍射分析对 BTFBPD 进行了表征,其几何参数显示出非共面扭曲特性。PI 具有高度的有机溶解性和热稳定性。夹在铟锡氧化物(ITO)底电极和铝顶电极之间的 PI 薄膜显示出两种可触及的导电状态,并可从低导电状态切换到高导电状态。配置为 Al/PI(BTFBPD-DPBPDA)/ITO 的存储器件具有闪存功能,而 Al/PI(BTFBPD-BTFBPDA)/ITO 则具有一次写入、多次读取(WORM)的存储器功能。所制造的器件的开启阈值电压较低,分别为-1.3 V(PI(BTFBPD-DPBPDA))和-1.7 V(PI(BTFBPD-BTFBPDA)),开启/关闭电流比均为 103 至 104。