Structural Insight on Aggregation and Orientation of TPD-based Polymers for Efficient Charge Transporting properties

Abstract

Development of organic semiconductors has been intensively investigated as promising material for organic electronics due to their unique advantages. In order to be applied to ubiquitous plastic electronics, structural insight of material is a key aspect to achieve high charge carrier mobility. For this reason, to check the relationship between intermolecular steric effect and the charge transporting properties, we synthesized the two types of copolymers which consist of the mono-TPD or bis-TPD as accepting unit. While the planarity and energy levels are not significantly different with the mono-TPD unit, the aggregation state is quite different and X-aggregation tendency seems to be stronger where the bis-TPD unit was incorporated. Overall characterization of the polymers were performed and it was found that the type of aggregation and orientation of the polymers in the final films, such as H-, J-, X- aggregation, was indeed important for high charge carrier mobility of the polymer.