Interface-Dependent Aggregation-Induced Delayed Fluorescence in Bottlebrush Polymer Nanofibers

Bottlebrush copolymers provide a covalent route to multicompartment nanomaterials that remain nanosegregated regardless of environmental conditions. This is particularly advantageous when combining polymers for optoelectronics, where the ability to control the interface between multiple chemically distinct polymers can be key to a device's function. Here we prepare bottlebrush nanofibers from an acridine- and triazine-based donor/acceptor pair, which have been shown to exhibit thermally activated delayed fluorescence (TADF) via through-space charge transfer (TSCT). By controlling the morphology of the donor and acceptor domains within the bottlebrush, random, miktoarm, and block bottlebrush morphologies are obtained. Using these materials, nanofibers may be prepared which (i) strongly exhibit TSCT TADF; (ii) exhibit switchable TSCT TADF based on aggregation of the fibers; or (iii) preserve the properties of the original donor and acceptor components. This work demonstrates that a bottlebrush strategy may be used to either force or prevent interactions between chemically dissimilar optoelectronic polymers in blended thin films. In this way, we establish a convenient method for either maximizing or minimizing donor-acceptor interactions in semiconductor polymer blends, using different arrangements of the same building blocks within a bottlebrush nanofiber.