Using the tight-binding Su-Schrieffer-Heeger (SSH) model and a nonadiabatic dynamical evolution method, the dynamic process of the charge carrier injection and transport through metal/ polymer/metal structure was studied, for which the polymer chain contains an impurity ion. The electron wave function was described by the time-dependent Schrdinger equation, while the polymer lattice was treated classically by the Newtonian equations of motion. It was found that the impurity ion acts as a control gate on the charge carriers, while the state of the control gate is determined by the strength of the electric field and the magnitude of the bias voltage.