Effect of molecular motion on migration of excess charge

An excess charge carrier, which is released from a deep trap, is supposed to transfer among migration states by local field and/or by diffusion. Space charge made of these excess carriers plays an important role in thermo-electrets in non polar as well as in polar polymers. We try to make a simulation calculation to get a survey on the behavior of excess charge by a process of polarization and depolarization in a polymer. Excess charge carrier is supposed to occupy deep traps in stable equilibrium at room temperature, and transfers to a shallow level state with temperature rise. We notice that over glass transition point T_g, where micro Brownian motion of chain molecule grows active, excited molecular motion promotes excess carrier to escape from trap and to migrate in a material more quickly