Cross-plane conductance through a graphene/molecular monolayer/Au sandwich.
Cross-plane conductance through a graphene/molecular monolayer/Au sandwich.
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DOI：
10.1039/c8nr06763e
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发表时间：
2018-11
期刊：
影响因子：
6.7
通讯作者：
Bing Li;Marjan Famili;E. Pensa;I. Grace;Nicholas J Long;Colin J. Lambert;Tim Albrecht;Lesley F Cohen
中科院分区：
文献类型：
--
作者：
Bing Li;Marjan Famili;E. Pensa;I. Grace;Nicholas J Long;Colin J. Lambert;Tim Albrecht;Lesley F Cohen
由单分子电结提供的功能尚未转化为单层或少层分子膜，其中制造有效和可再现的电接触是具有挑战性的瓶颈之一。在这里，我们在这个方向上迈出了重要的一步，证明了可以用夹在金和石墨烯电极之间的单层联苯-4，4 '-二硫醇（BPDT）分子膜进行良好的电接触。这种夹层器件结构是有利的，因为电流以垂直于石墨烯平面的“交叉平面”方式流过分子到达金衬底，从而产生高电导器件。我们阐明的跨平面石墨烯/分子/Au运输使用量子输运计算的性质，并介绍了一个简单的分析模型，它捕获的电流-电压特性的通用功能。结性质的不对称性是由电极电性质的差异、BPDT HOMO-LUMO能级的对准和石墨烯电极的特定特性引起的。结合硫醇-石墨烯接触的传输概率的理论描述，对结区域内的结性质的可缩放性的实验观察表明，10%至100%的分子与电极接触，这比文献中迄今为止实现的大几个数量级。
The functionalities offered by single-molecule electrical junctions are yet to be translated into monolayer or few-layer molecular films, where making effective and reproducible electrical contact is one of the challenging bottlenecks. Here we take a significant step in this direction by demonstrating that excellent electrical contact can be made with a monolayer biphenyl-4,4'-dithiol (BPDT) molecular film, sandwiched between gold and graphene electrodes. This sandwich device structure is advantageous, because the current flows through the molecules to the gold substrate in a 'cross-plane' manner, perpendicular to the plane of graphene, yielding high-conductance devices. We elucidate the nature of the cross-plane graphene/molecule/Au transport using quantum transport calculations and introduce a simple analytical model, which captures generic features of the current-voltage characteristic. Asymmetry in junction properties results from the disparity in electrode electrical properties, the alignment of the BPDT HOMO-LUMO energy levels and the specific characteristics of the graphene electrode. The experimental observation of scalability of junction properties within the junction area, in combination with a theoretical description of the transmission probability of the thiol-graphene contact, demonstrates that between 10% and 100% of the molecules make contact with the electrodes, which is several orders of magnitude greater than that achieved to date in the literature.