LAUSR

Abstract Two novel orange-emitting iridium (III) complexes (nbi) 2 Ir (bisq) ( 1 ) and (nbi) 2 Ir (dmbisq) ( 2 ) utilizing 2-naphthalen-1-yl-phenyl-1 H -benzimidazole as cyclometalated ligands were successfully synthesized and characterized. The effect of substituent groups in the ancillary ligands on their emission properties was systematically investigated. The experimental results indicate that complex 2 modified by introduction of methyl groups into its ancillary ligand exhibited higher photoluminescence and electroluminescence efficiencies than 1 without methyl groups. Such improved emission efficiencies were tentatively attributed to the suppressed intermolecular interactions in the solid state caused by the introduction of the methyl groups. Although the obtained efficiencies herein are not high, this work enlightens us to manipulate the photoluminescence and electroluminescence properties of iridium (III) complexes via reasonable modification in the ancillary ligand.