Charge transfer kinetics in non-polar media including a local molecular mode: the temperature dependence in wide ranges

摘要

The golden rule type algorithm for calculation of charge-transfer (CT) rates aimed at the description of charge carrier mobility in organic semiconductors is developed. The method circumvents the high temperature Redfield approximation applied in the earlier work (Basilevsky et al. in J Chem Phys 139:234102, 2013). This methodology borrows the Miller-Abrahams phenomenological scheme for the treatment of the electron conductivity in semiconductors. The scheme is widely applied now for the computational modeling of photosensitive organic materials. We provide the necessary molecular level input data for such computations. The approach covers large temperature range. It treats CT processes in non-polar media, including solvents with low dielectric permittivity, solid organic materials in which orientational polarization effects are strongly suppressed and various biological molecular objects. The Marcus-like polaron interaction mechanism is hardly applicable for such systems. The main quantity under study is the time-dependent relaxation function . It represents energy level fluctuations for the local promotion mode X(t) in a molecular CT dimer due to its interaction with the environment. Within the present approach, the dissipation of the reaction energy misfit promoted by this interaction significantly determines the CT kinetics. The function is expressed using the generalized Langevin equation technique. The importance of the analytic continuation procedure for is emphasized and discussed. The resulting computational treatment yields smooth kinetic curves for rate constants including their temperature dependence. The method can be applied to create a simulation of the conductivity of organic materials.