Incorporating hybrid charge transfer within a boron/nitrogen/oxygen-embedded scaffold for efficient yellow electroluminescence

A yellow thermally activated delayed fluorescence emitter featuring a distorted boron/nitrogen/oxygen-embedded polycyclic aromatic hydrocarbon is presented. It exhibits hybrid long- and short-range charge transfer character within a rigid framework for narrowed emission bandwidth and mitigating aggregation-caused quenching, enabling an electroluminescent device with an external quantum efficiency of 20.4%.