Charge Transfer through Redox Molecular Junctions in Nonequilibrated Solvents
Charge Transfer through Redox Molecular Junctions in Nonequilibrated Solvents
复制标题
非平衡溶剂中通过氧化还原分子结的电荷转移
DOI：
10.1021/acs.jpclett.0c00118
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Nitzan, Abraham
中科院分区：
文献类型：
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作者：
Kirchberg, Henning;Thorwart, Michael;Nitzan, Abraham
在介电溶剂环境中运行的分子传导通常使用基于分子-金属电极界面电子转移马库斯理论的动力学速率来描述。然而，此类系统中电荷转移的连续性质意味着溶剂不一定在此类过程中达到平衡。在这里，我们概括了该理论来解释溶剂非平衡，并考虑由耦合到两个金属电极并放置在可极化溶剂中的电子供体-受体系统组成的分子结。我们通过求解强摩擦和弱摩擦极限下的扩散方程来确定溶剂的非平衡分布，并计算充电电流及其波动行为。在极端限制下，即不存在溶剂或快速溶剂弛豫的情况下，电荷转移统计数据是泊松分布的，而它与这些限制之间的动态溶剂相关。发现了非平衡电流的克拉默式转换作为溶剂阻尼的函数。最后，我们提出了一种利用纳米结构溶剂通道中溶剂介电响应的几何控制来调整溶剂引起的阻尼的方法。
Molecular conduction operating in dielectric solvent environments is often described using kinetic rates based on the Marcus theory of electron transfer at a molecule–metal electrode interface. However, the successive nature of charge transfer in such a system implies that the solvent does not necessarily reach equilibrium in such processes. Here we generalize the theory to account for solvent nonequilibrium and consider a molecular junction consisting of an electronic donor–acceptor system coupled to two metallic electrodes and placed in a polarizable solvent. We determine the nonequilbrium distribution of the solvent by solving diffusion equations in the strong- and weak-friction limits and calculate the charge current and its fluctuating behavior. In extreme limits, the absence of the solvent or fast solvent relaxation, the charge-transfer statistics is Poissonian, while it becomes correlated by the dynamic solvent between these limits. A Kramers-like turnover of the nonequilibrium current as a function of the solvent damping is found. Finally, we propose a way to tune the solvent-induced damping using geometrical control of the solvent dielectric response in nanostructured solvent channels.