Excimer-emitting single molecules with stacked π-conjugated groups covalently linked at the 1,8-positions of naphthalene for highly efficient blue and green OLEDs

Abstract

Two efficient blue-light-emitting compounds, 1,8-bis(4-(N-carbazolyl)phenyl)naphthalene (BCzPN) and 1,8-bis(4-(10-phenylanthracen-9-yl)-phenyl)naphthalene (BPAPN), are designed and synthesized, in which two phenylcarbazole or diphenylanthracene units are closely stacked through bonding to the 1- and 8-positions of the naphthalene ring, resulting in strong intramolecular excimer emissions in solution or as a film. By utilizing BPAPN as an emitter, high efficiencies of 6 cd A−1 and 5.8% external quantum efficiency (EQE) at 100 cd m−2, and 8 cd A−1 and 5.8% EQE at 1000 cd m−2 are achieved in a non-doped blue device. By using BCzPN or BPAPN as a host, a DPAVBi-doped BCzPN based blue device gave high efficiencies of 15 cd A−1 and 6.5% EQE at 100 cd m−2, and 12 cd A−1 and 5.5% EQE at 1000 cd m−1, and a C545T-doped BPAPN based green device gave high efficiencies of 23 cd A−1 and 6.7% EQE at 100 cd m−2, and 22 cd A−1 and 6.7% EQE at 1000 cd m−2, respectively.