Simple heteroatom engineering for tuning the triplet energy of organometallic host materials for red, green and blue phosphorescent organic light-emitting diodes

Triplet energy tuning from 2.48 eV to 2.94 eV by just a simple change of heteroatom in the ligand structure of Be complexes was studied using azole based triplet host materials. Three Be organometallic host materials with azole type ligands were synthesized and could be used as the host materials from red to deep blue phosphorescent organic light-emitting diodes. High quantum efficiency was obtained in red, green, blue and deep blue devices using the Be complexes. In particular, a high quantum efficiency of 26.1% was achieved in blue phosphorescent organic light-emitting diodes.