Tunable electrical memory characteristics of brush copolymers bearing electron donor and acceptor moieties
作者:Kyungtae Kim、Yi-Kai Fang、Wonsang Kwon、Seungmoon Pyo、Wen-Chang Chen、Moonhor Ree
DOI:10.1039/c3tc30894d
日期:——
A series of brush copolymers bearing N-phenylcarbazole (PK) and 2-biphenyl-5-(4-ethoxyphenyl)-1,3,4-oxadiazole (BEOXD) moieties in various compositions were studied in detail, in particular their electrical memory characteristics, optical and electrical properties, morphological structures, and interfaces. Nanoscale thin films of the brush copolymers in devices were found to exhibit excellent unipolar electrical memory versatility, which can easily be tuned by tailoring the chemical composition and by changing the film thickness. Moreover, the molecular orbitals and band gap can be tuned by changing the chemical composition. The novel memory characteristics of these copolymers originate primarily from the cooperative roles of the ambipolar PK and BEOXD moieties, which have different charge trapping and stabilization properties. The electrical memory behaviors were found to occur via a favorable hole injection from the electrode and to be governed by trap-limited space-charge limited conduction combined with ohmic conduction and local filament formation. Overall, the brush copolymers are very suitable active materials for the low-cost mass production of high performance, polarity-free digital memory devices that can be operated with very low power consumption, high ON/OFF current ratios, and high stability.
详细研究了一系列不同组成的带有 N-苯基咔唑 (PK) 和 2-联苯-5-(4-乙氧基苯基)-1,3,4-恶二唑 (BEOXD) 部分的刷状共聚物,特别是它们的电记忆特性、光学和电学特性、形态结构和界面。研究发现,设备中刷状共聚物的纳米级薄膜表现出优异的单极电记忆多功能性,可以通过调整化学成分和改变薄膜厚度来轻松调节。此外,分子轨道和带隙可以通过改变化学成分来调节。这些共聚物的新颖记忆特性主要源于双极性 PK 和 BEOXD 部分的协同作用,它们具有不同的电荷捕获和稳定特性。发现电记忆行为是通过来自电极的有利空穴注入而发生的,并且受到陷阱限制空间电荷限制传导与欧姆传导和局部细丝形成相结合的控制。总体而言,刷状共聚物是非常适合低成本大规模生产高性能、无极性数字存储器件的活性材料,这些器件可以以非常低的功耗、高开/关电流比和高稳定性运行。