Blue and Green Phosphorescent Liquid-Crystalline Iridium Complexes with High Hole Mobility

Abstract

Blue- and green-emitting cyclometalated liquid-crystalline iridium complexes are realized by using a modular strategy based on strongly mesogenic groups attached to an acetylacetonate ancillary ligand. The cyclometalated ligand dictates the photophysical properties of the materials, which are identical to those of the parent complexes. High hole mobilities, up to 0.004 cm(2) V(-1) s(-1), were achieved after thermal annealing, while amorphous materials show hole mobilities of only approximately 10(-7) -10(-6) cm(2) V(-1) s(-1), similar to simple iridium complexes. The design strategy allows the facile preparation of phosphorescent liquid-crystalline complexes with fine-tuned photophysical properties.

Keywords: hole mobility; iridium; liquid crystals; phosphorescence; smectic phases.