Single-molecule diodes with high rectification ratios through environmental control
Single-molecule diodes with high rectification ratios through environmental control
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DOI：
10.1038/nnano.2015.97
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发表时间：
2015-06-01
影响因子：
38.3
通讯作者：
Venkataraman, Latha
中科院分区：
文献类型：
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作者：
Capozzi, Brian;Xia, Jianlong;Venkataraman, Latha
分子电子学的目标是通过使用亚纳米级的有源元件（1-3）来实现电子器件的小型化。单分子二极管是一种引导电流流动的电路元件（4），在40多年前首次被提出（5），并且由非对称分子组成，该非对称分子包括供体-桥-受体结构以模拟半导体p-n结。此后，几个单分子二极管已经在以不对称分子骨架（6-8）、分子电极连接体（9）或电极材料（10）为特征的结中实现。尽管取得了这些进展，但由于其电导率低、整流比低、对结结构极其敏感以及工作电压高，分子二极管的应用潜力有限（7- 9、11、12）。在这里，我们展示了一个强大的方法来诱导电流整流在对称的单分子结使用两个电极的相同的金属，但打破对称性，暴露相当不同的电极区域的离子溶液。这使我们能够通过简单地改变偏置极性来以非对称方式控制结的静电环境。通过这种方法，我们使用噻吩-1，1-二氧化物的对称低聚物，在低至370 mV的电压下可靠且可重复地实现了超过200的整流比（13，14）。通过利用由离子溶液的存在引起的结环境的变化，该方法提供了一种用于调谐非线性纳米级器件现象的一般路线，其可以潜在地应用于单分子结之外的系统中。
Molecular electronics aims to miniaturize electronic devices by using subnanometre-scale active components(1-3). A single-molecule diode, a circuit element that directs current flow(4), was first proposed more than 40 years ago(5) and consisted of an asymmetric molecule comprising a donor-bridge-acceptor architecture to mimic a semiconductor p-n junction. Several singlemolecule diodes have since been realized in junctions featuring asymmetric molecular backbones(6-8), molecule-electrode linkers(9) or electrode materials(10). Despite these advances, molecular diodes have had limited potential for applications due to their low conductance, low rectification ratios, extreme sensitivity to the junction structure and high operating voltages(7-9,11,12). Here, we demonstrate a powerful approach to induce current rectification in symmetric single-molecule junctions using two electrodes of the same metal, but breaking symmetry by exposing considerably different electrode areas to an ionic solution. This allows us to control the junction's electrostatic environment in an asymmetric fashion by simply changing the bias polarity. With this method, we reliably and reproducibly achieve rectification ratios in excess of 200 at voltages as low as 370 mV using a symmetric oligomer of thiophene-1,1dioxide(13,14). By taking advantage of the changes in the junction environment induced by the presence of an ionic solution, this method provides a general route for tuning nonlinear nanoscale device phenomena, which could potentially be applied in systems beyond single-molecule junctions.