Theory of electron-phonon interactions in organic crystals. Effect on charge carrier transport

Phonon modes in aromatic hydrocarbon crystals are classified to guide discussion of the electron-phonon interaction. The principal qualitative electron-phonon effects on charge carrier transport arise from the exchange integral variations due to lattice modes and from the binding energy due to frequency changes in out-of-plane molecular modes; other lattice and molecular modes have quantitative effects. The use of linear-response theory to calculate the conductivity for the two principal interactions is described. Each calculation embodies results applicable in the region intermediate between hopping and band transport, but as yet neither is completely analyzed in this region. Nevertheless, the fundamental processes governing charge carrier transport in these crystals now appear to be understood.