Microscopic jump mechanism of electron conductivity in photosensitive materials

Abstract

A procedure for calculating the microscopic electron transfer kinetics in disordered solid matrices is formulated. The procedure is oriented toward applications for estimating the mobility of charge carriers in modern photovoltaic devices. The proposed model for the elementary act of charge transfer deliberately excludes the effect the polarization modes of a medium have on its kinetics. The model is based on the evolution of a complex of local molecular modes polarized by an excessive molecular charge. The relaxation of this subsystem when interacting with acoustic phonon modes results in energy exchange between a local reaction center and the medium. Two alternative kinetic regimes are observed: a high-temperature regime corresponding to the jump dissipative reaction mechanism and a low-temperature regime corresponding to coherent electron transfer. A comprehensive description of the regions of transition between these mechanisms is impossible using this model. Efficient algorithms for calculating the rate constant are developed for each mechanism.