Multiscale modeling of materials and processes for organic electronics

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Conjugated molecular and polymer compounds are an important class of semiconducting materials and a wealth of novel devices are being developed, which contain thin films of those materials as the active layer: organic light-emitting diodes – OLEDs, organic field-effect transistors – OFETs, organic photovoltaic cells – OPVs, and (bio)sensors. Their performance are directly related to the electronic properties of the organic semiconductors, as well as to the physical processes taking place in the bulk and at the interfaces: charge injection, transport and collection, exciton formation and dissociation, light absorption and emission,… In this context, our aim is to contribute to the fundamental understanding of those issues, via modeling studies of materials and processes.

For this purpose, we employ a multiscale modeling approach combining: (i) force-field molecular mechanics/dynamics techniques for determining the supramolecular organization in thin films and at the interfaces; (ii) quantum-chemical methods (from semi-empirical Hartree-Fock to density functional theory) to determine the ground and excited state electronic structure, and (iii) Pauli/Quantum master equations- and Monte Carlo-based simulations to study the exciton and charge transport properties.

Conjugated molecules can also be envisioned as the elementary operating units in molecular-scale devices. Here our activities aim at determining the electronic structure of single molecules placed between two electrodes and understanding the transport properties of those molecular junctions, by using a density functional theory-based description.