Molecular diodes operating in the tunnelling regime are intrinsically limited to a maximum rectification ratio R of ∼10³. To enhance this rectification ratio to values comparable to those of conventional diodes (R ≥ 10⁵) an alternative mechanism of rectification is therefore required. Here, we report a molecular diode with R = 6.3 × 10⁵ based on self-assembled monolayers with Fc–C≡C–Fc (Fc, ferrocenyl) termini. The number of molecules (n(V)) involved in the charge transport changes with the polarity of the applied bias. More specifically, n(V) increases at forward bias because of an attractive electrostatic force between the positively charged Fc units and the negatively charged top electrode, but remains constant at reverse bias when the Fc units are neutral and interact weakly with the positively charged electrode. We successfully model this mechanism using molecular dynamics calculations.

中文翻译：

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由静电相互作用驱动的整流比超过105的分子二极管

在隧穿状态下操作分子二极管固有限制为最多整流比ř的〜10 ³。为了增强这种整流比率值与那些常规二极管（ř  ≥10 ⁵因此）整流的替代机制是必需的。在这里，我们报告了一个分子二极管，其基于具有Fc-C≡C-Fc（Fc，二茂铁基）末端的自组装单分子膜，R  = 6.3×10 ⁵。电荷传输中涉及的分子数（n（V））随所施加偏压的极性而变化。更具体地说，n（V由于带正电的Fc单元和带负电的上电极之间的静电吸引力，在正向偏压下会增加），但在Fc单元为中性且与带正电的电极弱相互作用时，反向偏压会保持恒定。我们使用分子动力学计算成功地对该机理进行了建模。