Enhancement of Red Thermally Assisted Fluorescence in Bottlebrush Block Copolymers

The morphology of a material used in organic electronics can be equally as important as the functional properties of its components. This is particularly true of polymers, which may be hierarchically constructed to regulate the interface between different functional monomers. Here, we examine four topologically distinct polymers for red thermally assisted fluorescence emission. The polymers consist of thermally activated delayed fluorescence sensitizer and fluorescent acceptor monomers arrayed in (i) linear random, (ii) linear block, (iii) bottlebrush random, or (iv) bottlebrush block polymer architectures. The crucial factor for achieving efficient red thermally assisted fluorescence in the thin film is found to be the separation of sensitizer and acceptor monomers into discrete nanoscale domains, which is best accomplished in the bottlebrush block morphology. This allows for rapid energy transfer from sensitizer to acceptor, while minimizing deleterious emission quenching interactions due to chain entanglement. This work demonstrates that nanosegregation is a viable approach to engineer the donor–acceptor architectures needed for efficient thermally assisted fluorescence.