Quantum coherence and carriers mobility in organic semiconductors

TL;DR

This paper introduces a quantum coherence-based model for charge transport in organic semiconductors, emphasizing decoherence effects and disorder, successfully predicting mobility and its temperature dependence consistent with experimental data.

Contribution

It presents a novel decoherence-driven model incorporating disorder effects to explain charge mobility in organic semiconductors, aligning theoretical predictions with experimental observations.

Findings

Predicted carrier mobility values matching experiments.

Modeled temperature dependence of mobility.

Demonstrated the role of decoherence in charge transport.

Abstract

We present a model of charge transport in organic molecular semiconductors based on the effects of lattice fluctuations on the quantum coherence of the electronic state of the charge carrier. Thermal intermolecular phonons and librations tend to localize pure coherent states and to assist the motion of less coherent ones. Decoherence is thus the primary mechanism by which conduction occurs. It is driven by the coupling of the carrier to the molecular lattice through polarization and transfer integral fluctuations as described by the hamiltonian of Gosar and Choi. Localization effects in the quantum coherent regime are modeled via the Anderson hamiltonian with correlated diagonal and non-diagonal disorder leading to the determination of the carrier localization length. This length defines the coherent extension of the ground state and determines, in turn, the diffusion range in the incoherent regime and thus the mobility. The transfer integral disorder of Troisi and Orlandi can also be incorporated. This model, based on the idea of decoherence, allowed us to predict the value and temperature dependence of the carrier mobility in prototypical organic semiconductors that are in qualitative accord with experiments.