Mott Lecture: Description of Charge Transport in Disordered Organic Semiconductors: Analytical Theories and Computer Simulations

Hopping of charge carriers via randomly distributed localized states with Gaussian energy spectrum is usually considered as the dominant charge transport mechanism in disordered organic semiconductors. Although much progress has been achieved in the theoretical description of such transport processes, many researchers follow the unlucky and groundless conviction that analytical solutions of the hopping transport problem are not possible. Monte Carlo computer simulations with phenomenological fitting of numerical results are often considered as the only theoretical tool suitable to describe hopping transport in disordered materials with the Gaussian energy spectrum. In this article, the transparent closed‐form analytical solutions for the hopping transport in organic disordered semiconductors are highlighted and some shortcomings of the phenomenological fittings are analyzed. Organic disordered semiconductors (ODSs) dominate the electrophotographic image recording and the display technology on the industrial scale and they are becoming more and more important for further applications in light‐emitting diodes, in field‐effect transistors, and in organic solar cells. Charge transport features are decisive for all these applications. Theory of charge transport in ODSs is reviewed with the emphasis on the transparent closed‐form analytical solutions.