Design of molecular materials for organics photovoltaics

Présentée par Clément Cabanetos Group Linear Conjugated Systems, CNRS Moltech-Anjou, Université d’Angers

Abstract : In recent years, thin-film organic solar cells have attracted considerable interest motivated by the possibility to develop light-weight and cost-effective photovoltaic energy sources by means of simple low-environmental impact processes. On the longer term organic photovoltaics could be expected to provide a possible complement or alternative to silicon technology.
Intensive multi-disciplinary research efforts developed in the past decade have generated impressive progress and several groups have recently announced conversion efficiencies exceeding 10% for devices fabricated by solution or vacuum processes.
While highly efficient solar cells have been initially fabricated using soluble conjugated polymers, the inherent polydispersity of conjugated polymers, the variability of their structural regularity, molecular weight and chain-length distribution as well as the presence of eventual end-group can render problematic the reproducibility of the structure and purity of the macromolecular materials and thus of the performances of the resulting devices.
As an alternative approach, the use of conjugated molecular chromophores as donor and or acceptor materials present several specific advantages in terms of unequivocal monodisperse chemical structure and reproducibility of synthesis and purification.
In this presentation, the molecular engineering of various classes of molecular donors, and more recently, molecular acceptors for organic solar cells will be discussed on the basis of the analysis of structure-properties relationships with an emphasis on the structural control of the light-harvesting properties, energy levels of the frontier orbitals and hole mobility.