Greenfield Jake L, Di Nuzzo Daniele, Evans Emrys W, Senanayak Satyaprasad P, Schott Sam, Deacon Jason T, Peugeot Adele, Myers William K, Sirringhaus Henning, Friend Richard H, Nitschke Jonathan R
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK.
Adv Mater. 2021 Jun;33(24):e2100403. doi: 10.1002/adma.202100403. Epub 2021 May 6.
Controlling the flow of electrical current at the nanoscale typically requires complex top-down approaches. Here, a bottom-up approach is employed to demonstrate resistive switching within molecular wires that consist of double-helical metallopolymers and are constructed by self-assembly. When the material is exposed to an electric field, it is determined that ≈25% of the copper atoms oxidize from Cu to Cu , without rupture of the polymer chain. The ability to sustain such a high level of oxidation is unprecedented in a copper-based molecule: it is made possible here by the double helix compressing in order to satisfy the new coordination geometry required by Cu . This mixed-valence structure exhibits a 10 -fold increase in conductivity, which is projected to last on the order of years. The increase in conductivity is explained as being promoted by the creation, upon oxidation, of partly filled orbitals aligned along the mixed-valence copper array; the long-lasting nature of the change in conductivity is due to the structural rearrangement of the double-helix, which poses an energetic barrier to re-reduction. This work establishes helical metallopolymers as a new platform for controlling currents at the nanoscale.
在纳米尺度上控制电流通常需要复杂的自上而下的方法。在此，采用一种自下而上的方法来证明由双螺旋金属聚合物组成并通过自组装构建的分子线内的电阻开关。当该材料暴露于电场时，确定约25%的铜原子从Cu氧化为Cu，而聚合物链未断裂。在铜基分子中维持如此高氧化水平的能力是前所未有的：在此通过双螺旋压缩得以实现，以满足Cu所需的新配位几何结构。这种混合价结构的电导率提高了10倍，预计可持续数年。电导率的增加被解释为氧化时沿着混合价铜阵列排列的部分填充轨道的产生所促进；电导率变化的持久性质是由于双螺旋的结构重排，这对再还原构成了能量障碍。这项工作将螺旋金属聚合物确立为在纳米尺度上控制电流的新平台。
