A theoretical study of asymmetric electron transport through linearly aromatic molecules

作者：Liu, Hongmei; He, Yuanyuan; Zhang, Jinjiang; Zhao, Jianwei^*; Chen, Li

来源：Physical Chemistry Chemical Physics, 2015, 17(6): 4558-4568.

DOI：10.1039/c4cp03887h

• CHARGE-TRANSPORT
• CURRENT RECTIFICATION
• JUNCTION CONDUCTANCE
• ANCHORING GROUPS
• DEPENDENCE
• RESISTANCE
• BEHAVIORS
• FORMULA
• THIOLS
• AU

Electron transport through a series of polyacene molecules connected via a pi-conjugated bridge (an anthracene molecule) was investigated theoretically by using the nonequilibrium Green's function formalism combined with density functional theory. The results have shown that the asymmetric current-voltage characteristics can be achieved by tuning the position of a side pi-bridge linked to the main conjugated backbone. The detailed analyses of the spatial distribution of molecular orbitals as well as the current density interpret how the location of pi-bridge strongly affects the intramolecular electronic coupling. The rectification in the molecular junction arises from the localization of the molecular orbitals near the Fermi level and the asymmetric shift of molecule orbital energy levels under positive and negative bias. The rectification ratio decreases with increasing the length of the pi-bridge which improves intramolecular electronic coupling between aromatic rings. Furthermore, the rectification properties of conjugated molecules are just slightly affected by the anchoring positions of thiol groups. These results demonstrated that the location and the length of pi-bridge, which induce the asymmetric intramolecular coupling, play key roles in the rectification of the linearly aromatic molecules

• 出版日期2015
• 单位生命分析化学国家重点实验室; 南京大学