Low variability of single-molecule conductance assisted by bulky metal-molecule contacts
Low variability of single-molecule conductance assisted by bulky metal-molecule contacts
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大体积金属分子接触辅助单分子电导的低变异性
DOI：
10.1039/c6ra15477h
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发表时间：
2016
期刊：
影响因子：
3.9
通讯作者：
Ferradás R
中科院分区：
文献类型：
--
作者：
Ferradás R
三甲基硅基乙炔基部分-CCSiMe 3（TMSE）作为金属中的锚定基团的详细研究|分子|金属结，采用实验和密度泛函理论相结合。它表明，TMSE锚定基团提供了改善的控制分子-基板内的金属安排|分子|金属结，甲基的空间体积限制了电极表面高透射结合位点的数量，导致原位断裂结和I（s）STM技术记录的电导直方图中的单个尖峰。由于TMSE组对可测量电导的表面结合构型的低可及性，只有约10%的金断裂结形成循环导致实验直方图中分子结的清晰形成。DFT计算的传输特性的结形成的TMSE接触的低聚（亚苯基）乙炔（OPE）为基础的分子在这里描述的占主导地位的隧道效应通过最高占据的分子轨道（HOMO）。这在这些TMSE接触的系统中产生了与在基于具有胺接触的非线性结构的0 PE衍生物的低电导型结中发现的类似的电导特性，所述低电导型结也通过基于HOMO的通道传导。
A detailed study of the trimethylsilylethynyl moiety, –CCSiMe3 (TMSE), as an anchoring group in metal|molecule|metal junctions, using a combination of experiment and density functional theory is presented. It is shown that the TMSE anchoring group provides improved control over the molecule–substrate arrangement within metal|molecule|metal junctions, with the steric bulk of the methyl groups limiting the number of highly transmissive binding sites at the electrode surface, resulting in a single sharp peak in the conductance histograms recorded by both the in situ break junction and I(s) STM techniques. As a consequence of the low accessibility of the TMSE group to surface binding configurations of measurable conductance, only about 10% of gold break junction formation cycles result in the clear formation of molecular junctions in the experimental histograms. The DFT-computed transmission characteristics of junctions formed from the TMSE-contacted oligo(phenylene)ethynylene (OPE)-based molecules described here are dominated by tunneling effects through the highest-occupied molecular orbitals (HOMOs). This gives rise to similar conductance characteristics in these TMSE-contacted systems as found in low conductance-type junctions based on comparably structured OPE-derivatives with amine-contacts that also conduct through HOMO-based channels.