Key laboratory of Analytical Chemistry for Life Science (Ministry of Education), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210008, PR China.
Chemphyschem. 2010 Jun 21;11(9):1895-902. doi: 10.1002/cphc.201000092.
We report the electron-transport behaviors of a number of molecular junctions composed of pi-conjugated molecular wires. From calculations performed by using density functional theory (DFT) combined with the non-equilibrium Green's function (NEGF) method, we found that the length-conductivity relations are diverse, depending on the particular molecular structures. The results reveal that the conductance-length dependence follows an exponential law for many conjugated molecules with a single channel, such as oligothiophene, oligopyrrole and oligophenylene. Therefore, a quantitative relation between the energy gap (E(g))(infinity) of the molecular wire and the attenuation factor beta can be defined. However, when the molecular wires have multichannels, the decay of conductance does not follow the exponential relation. For example, the conductance of porphyrin-based oligomers and fused thiophene decays almost linearly. The diversity of electron-transport behaviors of molecular junctions is directly dominated by the electron-transport pathway.
我们报告了由π共轭分子线组成的多个分子结的电子输运行为。通过使用密度泛函理论（DFT）与非平衡格林函数（NEGF）方法相结合进行的计算，我们发现，特定的分子结构会导致长度-电导率关系多样化。结果表明，对于许多具有单个通道的共轭分子，例如寡噻吩、寡吡咯和寡苯，电导-长度关系遵循指数定律。因此，可以定义分子线的能隙（E（g））（无穷大）与衰减因子β之间的定量关系。然而，当分子线具有多个通道时，电导的衰减并不遵循指数关系。例如，基于卟啉的低聚物和稠合噻吩的电导几乎呈线性衰减。分子结的电子输运行为的多样性直接由电子输运途径主导。
