Effect Of Temperature On Dynamics Of Polaron In Conductive Polymers

There have been a lot of knowledge about the properties of excitations (polarons, excitons, bipolarons and so on) in conjugated polymers which are used to make optoelectronic devices, including light-emitting diodes, lasers, and photovoltaic cells. Obviously, these are attributed to many works, such as the form of excitations and the dynamics of excitations. There are so many works about the dynamics of polaron. Many factors which can influence the dynamics of polarons have been demonstrated. For example, external electric field and application mode of the field can influence the stability of the polaron, interchain couping can influence the transmission of the polaron, impurities, defects, and collision between charge carriers can influence the dynamics of the polaron. However, the existence of lattice fluctuation has an important effect on the properties of polarons, which needs further research. In this letter, within a tight-binding electron-phonon interacting model modified to include thermal effects, theoretical temperature dependence of polaron dynamics is investigated by using a nonadiabatic evolution method in conjugated polymers. As the following:1,Temperature can effect the dynamics of polaron in conductive polymers. (1) It is found that the temperature effect destroys the translational symmetry of the electronic Hamitonian and leads the localized polaron state to become delocalized. Meanwhile many weakly localized polaron states are generated in the processes. Probability distribution of these states becomes equalized with the increase of temperature. (2) We can study the effect of changing the damping constant on the system. It is found that the damping constant can influence the time which the system reaches thermal equilibrium. To the extent, with increasing the damping coefficient, the time which the system reaches thermal equilibrium becomes short. (3) In this work, thermal effects on energy of system are also discussed. The results suggest that the electron can obtain energy from lattice easily at high temperature, the electric can release energy to the lattice easily at low temperature. 2,Temperature can effect the dynamics of photoexciations in conjugated polymers. (1) In the case of photoexcition formε1v toε1c, it is found that the temperature can effect the yield the polaronic excitons and the luminous frequency of that. With increasing the temperature, the yield of polaronic excitons becomes low and the luminous frequency becomes high. (2) In the case of photoexcition formε2v toε2c, it is found that temperature can reduce the life of the charge carriers, at the same time the yield of polaronic excitons increases. However, it is shown that the localized exciton becomes delocalized at temperatures and reduces the yield of polaronic excitons. From the above, with increasing the temperature, the yield of polaronic excitons becomes increscent and then reductive. (3) In the case of photoexcition between top energy levels, it is demonstrated that the yield of the excitons which are produced in photoexcition between odd energy levels (such as formε3v toε3c) becomes increscent and then reductive with increasing temperatures, in addition to the yield of 0K . It is found that the yield of the excitons which are produced in photoexcition between even energy levels (such as formε4v toε4c) becomes increscent and then reductive with increasing temperatures, including the yield of 0K .