摘要
Excellent thermoelectric performance in molecular junctions requires a high power factor, a low thermal conductance, and a maximum figure of merit(ZT) near the Fermi level. In the present work, we used density functional theory in combination with a nonequilibrium Green’s function to investigate the thermoelectric performance of carbon chain-graphene junctions with both strong-coupling and weak-coupling contact between the electrodes and the molecules. The results revealed that a room temperature ZT of 4 could be obtained for the weak-coupling molecular junction, approximately one order of magnitude higher than that reached by the strong-coupling junction. The reason for this is that strong interfacial scattering suppresses most of the phonon modes in weak-coupling systems, resulting in ultralow phonon thermal conductance. The influence of electrode width,electrode doping, and electrochemical gating on the thermoelectric performance of the weak-coupling system was also investigated, and the results revealed that an excellent thermoelectric performance can be obtained near the Fermi level.
基金
the National Key Research and Development Program of China(Grant No.2017YFB0701602)
the National Natural Science Foundation of China(Grant No.11674092)。
作者简介
Corresponding authors:Ke-Qiu Chen,email:keqiuchen@hnu.edu.cn;Corresponding authors:Wu-Xing Zhou,email:wuxingzhou@hnu.edu.cn。
