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▲ [15p-2T-11] Conductance through the carbon dioxides molecules in the vertically stacked graphene electrodes: First principles study
Keywords:Molecular conduction,Graphene
Understanding the conductance through single or few molecules is the fundamental interest in molecular electronics. In this research, configuration of the molecular electrodes is crucial. In order to study the role of electrode movement according to the molecules presence, vertically stacked electrodes is the most preferred configuration. As graphene has an ultra-high Young’s modulus of 1 TPa, and can withstand up to 20% mechanical deformation, graphene electrodes are good alternative to gold electrodes. In this research work, we study the electronic states and transmission properties of the carbon dioxide molecules placed in between the vertically stacked graphene electrodes (Fig. 1(A)) based on the first-principles and Non-Equilibrium Green’s Function techniques. Generalized gradient approximation (GGA) exchange and correlation functionals with Grimme van der Waals correction were used [1].
To find the optimum distance between the molecules and the graphene electrodes, geometric optimization was performed with a criterion of maximum force on each atom in the channel less than 0.05 eVÅ−1. The equilibrium distance between the carbon dioxide molecules and the electrodes varies according to the number of molecules and distance between the electrodes. In the case of 11 Å initial gap between the graphene electrodes, tip of the electrodes bend and make a optimized configuration as shown in Fig. 1 (A). When the initial gap between the electrodes is kept at 14 Å then two CO2 molecules vertically rearranged to the reach equilibrium configuration as shown Fig. 1(B). We can clearly see the current across these configurations change by orders of magnitude (Fig. 1 (C)). Detailed discussion will be given in the conference.
To find the optimum distance between the molecules and the graphene electrodes, geometric optimization was performed with a criterion of maximum force on each atom in the channel less than 0.05 eVÅ−1. The equilibrium distance between the carbon dioxide molecules and the electrodes varies according to the number of molecules and distance between the electrodes. In the case of 11 Å initial gap between the graphene electrodes, tip of the electrodes bend and make a optimized configuration as shown in Fig. 1 (A). When the initial gap between the electrodes is kept at 14 Å then two CO2 molecules vertically rearranged to the reach equilibrium configuration as shown Fig. 1(B). We can clearly see the current across these configurations change by orders of magnitude (Fig. 1 (C)). Detailed discussion will be given in the conference.