Qiu Li, Zhang Yanxi, Krijger Theodorus L, Qiu Xinkai, Hof Patrick Van't, Hummelen Jan C, Chiechi Ryan C
Stratingh Institute for Chemistry , Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands . Email:
Chem Sci. 2017 Mar 1;8(3):2365-2372. doi: 10.1039/c6sc04799h. Epub 2016 Dec 20.
This paper describes the rectification of current through molecular junctions comprising self-assembled monolayers of decanethiolate through the incorporation of C fullerene moieties bearing undecanethiol groups in junctions using eutectic Ga-In (EGaIn) and Au conducting probe AFM (CP-AFM) top-contacts. The degree of rectification increases with increasing exposure of the decanethiolate monolayers to the fullerene moieties, going through a maximum after 24 h. We ascribe this observation to the resulting mixed-monolayer achieving an optimal packing density of fullerene cages sitting above the alkane monolayer. Thus, the degree of rectification is controlled by the amount of fullerene present in the mixed-monolayer. The voltage dependence of varies with the composition of the top-contact and the force applied to the junction and the energy of the lowest unoccupied π-state determined from photoelectron spectroscopy is consistent with the direction of rectification. The maximum value of rectification = |(+)/(-)| = 940 at ±1 V or 617 at ±0.95 V is in agreement with previous studies on pure monolayers relating the degree of rectification to the volume of the head-group on which the frontier orbitals are localized.
本文描述了通过使用共晶镓铟（EGaIn）和金导电探针原子力显微镜（CP-AFM）顶部接触，在包含癸硫醇自组装单分子层的分子结中引入带有十一硫醇基团的C富勒烯部分来实现电流整流。整流程度随着癸硫醇单分子层与富勒烯部分接触时间的增加而增大，在24小时后达到最大值。我们将这一现象归因于形成的混合单分子层中富勒烯笼在烷烃单分子层上方达到了最佳堆积密度。因此，整流程度由混合单分子层中富勒烯的含量控制。整流的电压依赖性随顶部接触的组成、施加到结上的力而变化，并且由光电子能谱确定的最低未占据π态的能量与整流方向一致。在±1V时整流的最大值 = |(+)/(-)| = 940，或在±0.95V时为617，这与之前关于纯单分子层的研究一致，即整流程度与前沿轨道所在的头基体积有关。
