Design Rule of Assistant Dopant for High External Quantum Efficiency in Hyperfluorescence Organic Light‐Emitting Diodes

Abstract

We investigated the design rule of an assistant dopant for enhanced external quantum efficiency (EQE) in hyperfluorescence organic light‐emitting diodes by synthesizing two assistant dopants with thermally activated delayed fluorescent (TADF) features, BPAc and BPAcCz, by combining a benzophenone acceptor and a dimethylacridane donor. (Ed‐ this deleted sentence merely repeats the first sentence; it's important to keep the abstract as succinct as possible). BPAc had only the benzophenone acceptor and the dimethylacridane donor, whereas BPAcCz had an extra carbazole donor added to the BPAc structure. Comparison of the two assistant dopants revealed that the incorporation of the donor unit with a small dihedral angle degrades the efficiency of the hyperfluorescence devices by Dexter energy transfer. The hyperfluorescence devices with the BPAc and BPAcCz assistant dopants exhibited EQE of 16.6% and 15.0%, respectively.