Kinetic equation approach to the problem of rectification in asymmetric molecular structures

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Transport properties of asymmetric molecular structure are studied within the kinetic equation approach, taking into consideration the electron interaction in the self-consistent manner (SCF procedure). The device is made of a molecule (modeled as a quantum dot with discrete energy levels) which is asymmetrically coupled to the two metallic electrodes through the tunnel junctions. Electrical rectification follows from the combined effect of the geometric asymmetry in the molecular structure and simultaneously in the electrostatic potential spatial profile. Primarily the influence of broadening and charging effects on the charge and transport characteristics are investigated. Consequence of the broadening is to smooth the charge-voltage (N-V) and current voltage (I-V) functions, while the charging effect is rather responsible for the change of the slope of both N-V and I-V curves. Inclusion of the electron-electron repulsion results in significant enlargement of rectification ratio.