Nanomaterials Research Group, Computational Nanoscience & Technology Laboratory (CNTL), ABV-Indian Institute of Information Technology & Management (ABV-IIITM), Gwalior, 474015, India.
J Mol Model. 2013 Oct;19(10):4467-75. doi: 10.1007/s00894-013-1938-1. Epub 2013 Aug 9.
An ab initio approach was utilized to explore the electronic transport properties of 4'-thiolate-biphenyl-4-dithiocarboxylate (TBDT) sandwiched between two electrodes made of various materials X (X = Cu, Ag, and Au). Analysis of current-voltage (I-V) characteristics, rectification performance, transmission functions, and the projected density of states (PDOS) under various external voltage biases showed that the transport properties of these constructed systems are markedly impacted by the choice of electrode materials. Further, Cu electrodes yield the best rectifying behavior, followed by Ag and then Au electrodes. Interestingly, the rectification effects can be tuned by changing the torsion angle between the two phenyl rings, as well as by stretching the contact distances between the end group and the electrodes. For Cu, the maximum rectifying ratio increases by 37 % as the contact distance changes from 1.7 Å to 1.9 Å. This is due to an increase in coupling strength asymmetry between the molecule and the electrodes. Our findings are compared with the results reported for other systems. The present calculations are helpful not only for predicting the optimal electrode material for practical applications but also for achieving better control over rectifying performance in molecular devices.
采用从头算方法研究了由不同材料 X（X=Cu、Ag 和 Au）制成的两个电极夹在 4'-硫代联苯-4-二硫代羧酸酯（TBDT）之间的电子输运性质。对电流-电压（I-V）特性、整流性能、传输函数以及在不同外电压偏置下的投影态密度（PDOS）的分析表明，这些构建系统的输运性质明显受到电极材料选择的影响。此外，Cu 电极产生最佳的整流行为，其次是 Ag 电极，然后是 Au 电极。有趣的是，通过改变两个苯环之间的扭转角以及拉伸端基与电极之间的接触距离，可以调节整流效果。对于 Cu，当接触距离从 1.7 Å 变为 1.9 Å 时，最大整流比增加了 37%。这是由于分子和电极之间的耦合强度不对称性增加所致。我们的发现与其他系统的结果进行了比较。这些计算结果不仅有助于预测实际应用中最佳的电极材料，还有助于更好地控制分子器件中的整流性能。
