State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering & Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM) & Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, China.
Nat Chem. 2022 Oct;14(10):1158-1164. doi: 10.1038/s41557-022-01003-1. Epub 2022 Jul 28.
Intermolecular charge transport plays an essential role in organic electronic materials and biological systems. To date, experimental investigations of intermolecular charge transport in molecular materials and electronic devices have been restricted to conjugated systems in which π-π stacking interactions are involved. Herein we demonstrate that the σ-σ stacking interactions between neighbouring non-conjugated molecules offer an efficient pathway for charge transport through supramolecular junctions. The conductance of σ-σ stacked molecular junctions formed between two non-conjugated cyclohexanethiol or single-anchored adamantane molecules is comparable to that of π-π stacked molecular junctions formed between π-conjugated benzene rings. The current-voltage characteristics and flicker noise analysis demonstrate the existence of stacked molecular junctions formed between the electrode pairs and exhibit the characteristics of through-space charge transport. Density functional theory calculations combined with the non-equilibrium Green's function method reveal that efficient charge transport occurs between two molecules configured with σ-σ stacking interactions.
分子间电荷输运在有机电子材料和生物系统中起着至关重要的作用。迄今为止，对分子材料和电子器件中分子间电荷输运的实验研究仅限于涉及π-π堆积相互作用的共轭体系。在此，我们证明了相邻非共轭分子之间的σ-σ堆积相互作用为通过超分子结进行电荷输运提供了有效途径。由两个非共轭环己硫醇或单锚定金刚烷分子形成的σ-σ堆积分子结的电导与由π-共轭苯环形成的π-π堆积分子结的电导相当。电流-电压特性和闪烁噪声分析表明，在电极对之间形成了堆叠的分子结，并表现出了通过空间电荷输运的特征。密度泛函理论计算结合非平衡格林函数方法表明，在具有σ-σ堆积相互作用的两个分子之间发生了有效的电荷输运。
