Manipulating efficiencies through modification of N-heterocyclic phenyltriazole ligands for blue iridium(III) complexes

Abstract

Novel kinds of blue-emitting heteroleptic iridium(III) complexes (fpdmtz)2Ir(mpypz) (1), (fpmptz)2Ir(mpypz) (2) and (fpmptz)2Ir(pypz) (3) with N-heterocyclic phenyltriazole ligands were designed and synthesized under the guidance of theoretical calculations. Especially, the effect of substituent groups on their emission properties was systematically studied through introducing methyl and propyl moieties into the cyclometalated and ancillary ligands. The experimental results showed that 2 and 3 modified by propyl groups exhibited higher photoluminescence and electroluminescence efficiencies than 1 modified by methyl moiety in its cyclometalated ligands. Such greatly improved emission efficiencies were tentatively attributed to the suppressed intermolecular interactions in solid state caused by the introduction of propyl group, indicating that the photoluminescence and electroluminescence properties of iridium(III) complexes can be manipulated just by modifying simple small molecule groups into the cyclometalated ligands.