Theoretical Description of Structural and Electronic Properties of Organic Photovoltaic Materials

Abstract

We review recent progress in the modeling of organic solar cells and photovoltaic materials, as well as discuss the underlying theoretical methods with an emphasis on dynamical electronic processes occurring in organic semiconductors. The key feature of the latter is a strong electron-phonon interaction, making the evolution of electronic and structural degrees of freedom inseparable. We discuss commonly used approaches for first-principles modeling of this evolution, focusing on a multiscale framework based on the Holstein-Peierls Hamiltonian solved via polaron transformation. A challenge for both theoretical and experimental investigations of organic solar cells is the complex multiscale morphology of these devices. Nevertheless, predictive modeling of photovoltaic materials and devices is attainable and is rapidly developing, as reviewed here.

Molecular dynamics and charge transport in organic semiconductors: a classical approach to modeling electron transfer

“…A challenge in this approach is the accurate definition of effective mass and friction, which are both complex functions of the polaron's interaction with the surrounding environment. We note that the interaction of charges with surrounding vibrations is a very active area of theoretical research 20 that will hopefully lead to clarifications regarding the mass, friction, and other properties of polarons in organic semiconductors.…”

Evidence of Polaron Excitations in Low Temperature Raman Spectra of Oxalic Acid Dihydrate

“…The importance of understanding the influence of lattice defects on optical, conduction and transport properties of materials manifests repeatedly in the study of organic photovoltaic materials for solar cells 1 and high -Tc superconductors 2 , while proton dynamics deserves special attention because of the role hydrogen bonding plays in biochemistry.…”

Charge delocalization characteristics of regioregular high mobility polymers

“…Thus, both ordering of the material and coupling between electronic and vibrational degrees of freedom ultimately define charge transport in the system. 16 In the case of hopping transport in disordered systems, the interchain ordering, or morphology, is a deterministic factor that limits transport. 17–19 Electron–phonon coupling determining the reorganization energies for single electron-transfer events may be a lesser factor, however, its role nevertheless needs to be clarified in relation to the regiochemistry at a single polymer chain level.…”