Electronic disorder in crystalline organic semiconductor: the role of thermal motions modulating the transfer integrals in polyacenes

The effect of thermal structural fluctuations on the modulation of the transfer integrals between close molecules is studied using a combination of molecular dynamics simulations and quantum chemical calculations of the transfer integral. We have found that the fluctuations of the transfer integrals are of the same order of magnitude of their average value for two common organic semiconductors an observation that puts into question the currently adopted models for charge transport in organic semiconductors and identifies in the dynamic electronic disorder the limiting factor for the charge carrier mobility.