FWF - Organische Mixed-Valence - Electron Transfer Kinetics of Organic Mixed-Valence Compounds

Triarylamines are very important hole transport components in optoelectronic devices. Based on previous cooperative work the applicants plan to use the now established methodology to investigate complex organic mixed valence compounds that are based on bis-triarylamine radical cations. Using dynamical ESR-spectroscopy we would like to investigate beside the rate constants of the intermolecular electron transfer, the thermodynamic activation parameters H# and S# obtainable from temperature dependent measurements and the activation volume V# by applying high pressure methods. By comparing the electron transfer parameters determined from optical spectra and dynamic ESR spectroscopy, several aspects shall be elucidated. First, solvent friction plays a significant role in the hole transfer process which shall therefore be investigated in detail by using various solvent with different physical properties and ionic liquids. Second, because orientational aspects between the triarylamine units will ultimately govern the hole transfer rates, new organic mixed valence compounds in which the triarylamine redox centres are oriented in a fixed relative position will be synthesised and investigated. Third, we will focus on the influence of localised bridge oxidation states on the hole transfer rate between two triarylamine redox centres. The elucidation of these three aspects will help to get a better insight into the hole transfer phenomena of triarylamines which then will ultimately allow to optimise their use in optoelectronic materials.