Deep blue cause for elation

摘要

Blue luminescence is critical for full-colour displays and lighting based on organic light-emitting diodes. Evaporated small molecules and solution-processed dendritic green and red phosphorescent materials based on iridium(III) complexes have offered high device efficiency. However, highly luminescent deep-blue phosphorescent materials have proved elusive. For small-molecule phosphorescent iridium(III) complexes the challenges are the choice of the host required to stop detrimental intermolecular interactions of the emitters and the ability to co-deposit the materials uniformly by evaporation and without isomerisation. This is exacerbated for saturated blue phosphorescence as many hosts quench the luminescence due to their low triplet energy.