Search

Charge carrier hopping transport is generally taken from Miller-Abrahams and Marcus transition rates. Based on the Miller-Abrahams theory and nearest-neighbour range hopping theory, Apsley and Hughes developed a concise calculation method (A-H method) to study the hopping conduction in disordered systems. Here, we improve the A-H method to investigate the charge carrier hopping transport by introducing polaron effect and electric field based on Marcus theory and variable-range hopping theory. This improved method can well describe the contribution of polaron effect, energetic disorder, carrier density, and electric field to the charge carrier transport in disordered organic semiconductor. In addition, the calculated results clearly show that the charge carrier mobility represents different polaron effect dependence with the polaron activation energy and decreases with increasing electric field strength for large fields. [ABSTRACT FROM AUTHOR]

The ratio between mobility and diffusion parameters (Einstein relation) in organic semiconductors has been a debating issue in the recent years. In this paper we developed an analytical model based on hopping transport theory and the Gaussian density of states. The validity of Einstein relation in organic semiconductors is discussed. It is shown that the classic Einstein relation is invalid for organic semiconductors, even for the carrier concentration for experimental purpose. [ABSTRACT FROM AUTHOR]