Advanced organic materials for light assisted charge separation

Abstract

We propose new donor-acceptor units as light harvesting heterojunctions systems and their host-guest systems, aiming higher performance and device lifetime. Thus, phenothiazine oligomers will be used as donor (D) units and S,N-heteroacene oligomers as acceptor (A) units. Host-guest systems will be prepared in silica, sodium-aluminum silicate, phenyl-silicate, and Naphthalenediimide-silica by the sol-gel method and spin-coated as films. These host-guest films will be also prepared in the presence of the ionic liquid (1-Butyl-3-methylimidazolium BF4). In addition, photovoltaic devices of selected heterojunctions and host-guest systems will be prepared. Charge transfer efficiency will be probed from photoluminescence quenching and photovoltaic efficiency will be probed from the current response for the applied voltage under simulated solar irradiation. Since molecular systems with light assisted functionalities incorporated in inorganic and hybrid hosts tend to have lower degradation rates, we are going to perform a comparative study of light assisted charge separation efficiency as a function of time. The morphology of the films will be characterized from optical and scanning electron microscopy and correlated to the light harvesting efficiency. The films will be extracted from the substrate and characterized by solid state high resolution NMR in order to elucidate intermolecular interactions, size domain of the D and A regions, ion mobility (for the samples with the ionic liquid), and molecular motion. This project aims to introduce new routes towards efficient and durable organic photovoltaic materials. (AU)