Li Shi, Jiang Yuxuan, Wang Yongfeng, Sanvito Stefano, Hou Shimin
Center for Nanoscale Science and Technology, Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, China.
School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland.
J Phys Chem Lett. 2021 Aug 12;12(31):7596-7604. doi: 10.1021/acs.jpclett.1c01996. Epub 2021 Aug 4.
Manipulating the nature of the charge carriers at the single-molecule level is one of the major challenges of molecular electronics. Using first-principles quantum transport calculations, we have investigated the electronic transport properties of imidazole-linked single-molecule junctions and identified the hydrogen atom bonded to the pyrrole-like nitrogen in imidazole as a switch to tune the polarity of the charge carriers. Our calculations show that the chemical nature of the imidazole anchors is dramatically altered by dehydrogenation, which changes the dominant charge carriers from electrons to holes. It is also revealed that upon dehydrogenation the interfacial Au-N bonds are modified from donor-acceptor-like to covalent, along with a significant promotion of the low-bias conductance and the junction stability. At variance with other traditional methods that always require drastic modifications of the junction structure, our findings provide a promising approach to tailor in situ the polarity of charge carriers in molecular electronic devices.
在单分子水平上操控电荷载流子的性质是分子电子学的主要挑战之一。通过第一性原理量子输运计算，我们研究了咪唑连接的单分子结的电子输运性质，并确定了与咪唑中吡咯样氮原子相连的氢原子作为调节电荷载流子极性的开关。我们的计算表明，脱氢会显著改变咪唑锚定基团的化学性质，使主导电荷载流子从电子变为空穴。研究还发现，脱氢后界面处的金 - 氮键从类似供体 - 受体键转变为共价键，同时低偏置电导和结稳定性得到显著提升。与其他总是需要对结结构进行剧烈修改的传统方法不同，我们的研究结果为原位调整分子电子器件中电荷载流子的极性提供了一种有前景的方法。
