Molecular design approach of increasing the triplet energy of host materials using pyrrole as a core structure

Abstract

We developed and synthesized 9,9′-(1-phenyl-1H-pyrrole-2,5-diyl)bis(9H-carbazole) (PPyCz2) as a hole transport type high triplet energy host material for blue phosphorescent organic light emitting diodes. We approached the molecular design by inserting a pyrrole moiety to prevent extension of conjugation of molecule and achieved a high triplet energy of 2.99 eV in the PPyCz2 host. Furthermore, the PPyCz2 host showed a high external quantum efficiency of 14.8% in blue phosphorescent organic light emitting diodes.