Efficient deep blue fluorescent emitter showing high external quantum efficiency

A benzoanthracene-cored deep blue-emitting compound, N6,N9-bis(4-cyano-phenyl)-N3,N9-diphenylspiro[benzo[de]anthracene-7,9′-fluorene]-3,9-diamine was synthesized and which has an exchange energy of ∼0.2 eV between the singlet and triplet state. OLED devices doped with this new deep blue emitter showed comparable device performances and delayed fluorescence via the reoccupation of the singlet excitons from the triplet excitons with long lifetimes. In particular, the 10%-doped device exhibited the maximum external quantum efficiency of 14.8% and current efficiency of 15.1 cd/A with Commission International de L'Edairge coordinates of (0.14, 0.11).