Dynamics Of Polarons In Organic Conjugated Polymers With Side Radicals

Based on the one-dimensional tight-binding Su-Schrieffer-Heeger (SSH) model and by using a nonadiabatic molecular dynamic method, we studied some static properties of polymer and the dynamical process of polaron in a polymer chain.1. we investigated some static properties of polymer and the dynamical process of polaron in polymer with impurity ions. (1)It is found that the polymer band gap is different in polymer with different number of impurity ions. It is also found that the band gap of conjugated polymer decreases with the increasing of the impurities potential strength. (2) In polymer with the same impurity ions (VP>0), we found that the velocities of the electron and the hole polaron are different. The polaron is accelerated by an external electric field to arrive a stationary velocity, then the polaron will collide with impurities. There is the coulomb repulsion between electron polaron and impurity ions (VP>0), which is similar to the potential barrier, while there is the coulomb attraction between the hole polaron and impurity ions (VP>0), which is similar to the potential well. Electron and hole polaron have different coulomb interaction with impurity ions, which causes the polaron speed of plus and minus difference. (3)The average velocity of polaron is affected by the distance between impurity ions. When impurity ions have a little distance, for example, the distance of impurity ions is six times lattice constant, the average velocity of the electron polaron is faster than the hole polaron. In addition, it is found that the average velocity of polaron decreases with the increasing of impurities potential strength.2. We investigated some static properties of polymer and the dynamical process of polaron in a polymer chain with side radicals. (1) In the polymer chain with the electronic group with exclusion as side radicals, it is found that the electron is easy to transfer to the main chain, namely, N-type semiconductor material. On the contrary, if the electronic group with attractive replace side radicals, it is found that theπ-electron of the main chain is easy to transfer to the side radicals, namely, P-type semiconductor material. Local degenerate energy levels in the band gap are formed by adding the side radicals. Local energy levels approach to the center of the band gap with the increasing of the hopping integral (t1) between theπ-electron of the main chain and the unpaired electrons at the side radicals. And local energy levels approach to the valence band and conduction band with the increasing of the potential energy of the side radicals. (2) It is found that the velocities of the electron and the hole polaron are different due to the influence of side radicals, it is because polaron and side radicals have different interaction, which causes the polaron speed of plus and minus difference. The polaron is accelerated by an external electric field and arrives a stationary velocity, then the polaron will collide with the side radicals, when the distance of side radicals is sixteen times lattice constant, the velocity of the electron polaron is far faster than the hole polaron. It is shown that the average velocity of the electron polaron decreases with the increasing of the hopping integral (t1), but the average velocity of the hole polaron increases with the increasing of the hopping integral (t1). And it is found that the average velocity of the polaron is affected by the distance of side radicals, the average velocity of the electron polaron almost be a constant with the increasing of the distance of the side radicals, while the average velocity of the hole polaron decreases suddenly as the distance of the side radicals arrives 14-22 lattice constant. In addition, it is also found that the average velocity of the polaron relates to potential energy of the side radicals .