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Abstract Eight new iridium (III) complexes 1‐8, with 1, 3, 4‐oxadiazole (OXD) derivatives as the cyclometalated CN ligand and/or the ancillary NN ligands are synthesized and their electrochemical, photophysical, and solid‐state light‐emitting electrochemical cell (LEC) properties are investigated. Complexes 1, 2, 7 and 8 are additionally characterized by single crystal X‐ray diffraction. LECs based on complexes 1‐8 are fabricated with a structure indium tin oxide (ITO) /poly (3, 4‐ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) /cationic iridium complex: ionic liquid/Al. LECs of complexes 1 – 6 with OXD derivatives as the cyclometalated ligands and as the ancillary ligand show yellow luminescence (λ max = 552–564 nm). LECs of complexes 7 and 8 with cyclometalated CN phenylpyridine ligands and an ancillary NN OXD ligand show red emission (λ max 616–624 nm). Using complex 7 external quantum efficiency (EQE) values of >10% are obtained for devices (210 nm emission layer) at 3. 5 V. For thinner devices (70 nm) high brightness is achieved: red emission for 7 (8528 cd m −2 at 10 V) and yellow emission for 1 (3125 cd m −2 at 14 V).
Zhang et al. (Thu,) studied this question.