Electronic structure of novel low band gap conjugated polymers
(English)Manuscript (preprint) (Other academic)
The electronic structures of two novel low band gap conjugated polymers have been studied. Both materials are conjugated alternating copolymers based on fluorene units and low band gap donor-acceptor-donor units. The emphasis in this study has been to study the valence and the conduction bands. In particular the degree of localization or delocalization along the polymers and the symmetry of these states have been studied, since these features can be related to their transport properties. The main experimental part of this work is photoelectron spectroscopy, near-edge X-ray photon absorption and resonant photoemission. These techniques have been used to probe the frontier electronic structure of these systems. The experimental results are interpreted with the help of density functional theory calculations. The valence bands are dispersed originating from orbitals delocalized along the polymer chain shile the conduction bands are more flat, as they are derived from orbitals localized on the acceptor units. This band structure would predict good hole transporting properties but poor electron transport.
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-88047OAI: oai:DiVA.org:liu-88047DiVA: diva2:601411