Mode-selective ab-initio photoinduced dynamics in conjugated polymers

ended

Organic conjugated materials (OCMs) possess unique electronic properties compared with other traditional semiconductor materials, due to the delocalization and high polarizability of π-electrons supporting the motion of charge carriers, as well as their significant electronic correlation and electron-phonon couplings. They present a remarkable flexibility allowing to tune their optical, electronic and mechanical properties at will through molecular engineering, making OCMs most suitable for a broad range of technical applications ranging from optoelectronics, as components of light-emitting diodes, to photovoltaic cells. Rigidity and conjugation, as well as the interchromophoric geometry, play a crucial role in the primary energy transfer mechanisms along aconjugated polymer (i.e., through-bond or through-space processes). The strong coupling between the electronic and nuclear degrees of freedom leads to self-trapping and spatial localization of excitons, in a region whose spatial length is determined by conformational defects. Manipulating these nuclear degrees of freedom may lead to a blockade or an enhancement of energy transfer along the bond. Recent experiments have pointed out that in specific polymers exciton transfer is a coherent process rather than a sequence of incoherent hopping type events. The accurate description of these photoinduced pathways considering all degrees of freedom involved constitutes a challenge to date. The goal of the fellowship is to advance state-of-the-art computational methods for describing the photoinduced and laser-driven, coupled electron-nuclear dynamics of large conjugated molecules, with the aim to include quantum coherence effects and to enable predictive calculations of exciton dynamics and of energy transfer in such polymeric systems. The researcher will carry out the fellowship in the Laboratory of Collisions, Aggregates and Reactivity, University of Toulouse III, under the supervision of Dr. Nadine Halberstadt.