Three neutral cyclometalated iridophosphors with steric hindrance for efficient yellow electroluminescence

Three new neutral phosphorescent iridium(III) complexes (Ir1, Ir2, and Ir3) with steric hindrance are designed and synthesized by incorporating various auxiliary ligands. These complexes display intense yellow phosphorescence (549 nm with 584 nm as shoulder for Ir1, 534 nm with 570 nm as shoulder for Ir2, 529 nm with 568 nm as shoulder for Ir3), high photoluminescence efficiency (0.35–0.43) and moderate full width at half maximum (75–78 nm). The effective steric hindrance of these complexes can be realized by incorporating bulky bis(trifluoromethyl)phenyl moiety, which is in favor of efficient organic light-emitting diodes. The peak current efficiency, power efficiency and external quantum efficiency of electroluminescence are as high as 66.33 cd/A, 58.99 lm/W, and 20.12%, respectively.