Aggregation Types and Orientation Directions of TPD-based Polymers for Efficient Charge Transporting Properties

Abstract

Semiconducting molecules can have a pre-aggregated state in the solution prior to forming orientation states. The microstructure control of pre-aggregation in the solution can make molecular alignment and orientation more effectively lead to enhanced device performance. The aggregation state of the molecules has been studied as a way to enhance the alignment in thin films. On the other hand, the aggregation type in thin-film states has not been fully elucidated, especially in semiconducting polymer films. To the best of our knowledge, this is the first report that investigates the change in the aggregation type in thin films by varying the polymer structure and clarifies the relationship between the aggregation type and charge transporting properties. From a structural viewpoint, understanding the type of aggregation could be a key factor in interpreting the various characteristics that cannot be explained by orientation type alone.