Modelling charge transport in organic semiconductors: from quantum dynamics to soft matter

Abstract

The charge carrier dynamics in organic semiconductors has been traditionally discussed with the models used in inorganic crystalline and amorphous solids but this analogy has severe limitations because of the more complicated role of nuclear motions in organic materials. In this perspective, we discuss how a new approach to the modelling of charge transport is emerging from the alliance between the conventional quantum chemical methods and the methods more traditionally used in soft-matter modelling. After describing the conventional limit cases of charge transport we discuss the problems arising from the comparison of the theory with the experimental and computational results. Several recent applications of numerical methods based on the propagation of the wavefunction or kinetic Monte Carlo methods on soft semiconducting materials are reviewed.

The Transient Localization Scenario for Charge Transport in Crystalline Organic Materials

“…[20,21,22,23,24,25] Despite a number of review articles and books published on the subject of charge transport in organic semiconductors, this important theoretical framework has not been comprehensively described in any review yet (although some aspects are mentioned in Refs. [21,26,27]). Because it is now reaching its full theoretical maturity, and in order to set the ground for more systematic experimental confirmations, we consider that it is now timely to provide an overview of the transient localization scenario.…”

Optoelectronic and Semiconducting Properties of Conjugated Polymers Composed of Thiazolo[5,4-d]thiazole and Arene Imides Linked by Ethynylene Bridges

“…3,45,52,53 Since the inner reorganization energy controls the charge-phonon 8 coupling, if λ 1 ≈ λ 2 , we can write λ i ≈ 2λ 1 , and this condition can be satisfied when the molecular structure is not largely deformed during the ionization process. 54 The charge hopping transport is favored by a small polaron binding energy (E pol ), defined as the relaxation energy of an ionized molecule.…”

“…34,35,52 In the case of symmetrically arranged polymers, e 1 = e 2 as the infinite chains can be considered as equivalent molecules in the crystal and equation (6) and (7) can be written as. 3,34,45,52 ‫ݐ|‬ ଵଶ ି | = ா ಽశభ ିா ಽ ଶ (8)…”

Multi-Scale Modeling of Bulk Heterojunctions for Organic Photovoltaic Applications

“…At the other extreme to continuum drift-diffusion modeling, charge-carrier transport has been studied on the atomic scale using quantum chemical calculations and time-dependent perturbation theory (Brédas et al, 2004;Cheung & Troisi, 2008;Coropceanu et al, 2007). Such calculations are computationally intensive and are generally restricted to systems on the nanometer scale and therefore cannot be used to study transport between donor-acceptor domains on the 10 nm scale, let alone device-scale transport.…”