Solubilised bright blue-emitting iridium complexes for solution processed OLEDs

Abstract

Combining a sterically bulky, electron-deficient 2-(2,4-difluorophenyl)-4-(2,4,6-trimethylphenyl)pyridine (dFMesppy) cyclometalating C^∧N ligand with an electron rich, highly rigidified 1,1′-(α,α′-o-xylylene)-2,2′-biimidazole (o-xylbiim) N^∧N ligand gives an iridium complex, [Ir(dFMesppy)₂(o-xylbiim)](PF₆), that achieves extraordinarily bright blue emission (Φ_PL = 90%; λ_max = 459 nm in MeCN) for a cationic iridium complex. This complex is compared with two reference complexes bearing 4,4′-di-tert-butyl-2,2′-bipyridine, and solution-processed organic light emitting diodes (OLEDs) have been fabricated from these materials.