Nearly 100% Exciton Utilization via Hybridized Inter- and Intramolecular Triplet Exciton Harvesting Channels in Blue Fluorescent Organic Light-Emitting Diodes

A highly efficient anthracene-based 5-(4-(10-phenylanthracen-9-yl)phenyl)-5H-benzofuro[3,2-c]carbazole (ATDBF) with nearly 100% exciton utilization efficiency is developed for highly efficient nondoped blue organic light-emitting diodes (OLEDs) through inter- and intramolecular triplet exciton up-converting mechanisms. The ATDBF emitter opens hybridized hot excitons, triplet-triplet fusion (TTF), and mixed TTF/hot exciton channels for triplet exciton to singlet exciton conversion. The molecular design adopting a benzofuro[3,2-c]carbazole (BFCz) donor manages the singlet and triplet excited states for hybridized triplet exciton up-conversion mechanisms, which enable a high external quantum efficiency (EQE) of 7.93% in the ATDBF blue device with color coordinates of (0.15, 0.06). This is one of the best efficiencies of the nondoped blue OLEDs with a y color coordinate below 0.06.