Phosphorescent Ionic Iridium(III) Complexes Displaying Counterion‐Dependent Emission Colors for Flexible Electrochromic Luminescence Device

Abstract Stimulus‐responsive luminescent materials have drawn considerable interest because they are ideal candidates for optoelectronic applications. Herein, a series of phosphorescent iridium(III) complexes [(CZPY)₂IrNH]⁺X⁻ (X⁻ = PF₆⁻, I⁻, Br⁻, Cl⁻) containing two NH moieties in the N^N ligand is reported. These complexes exhibit significantly counterion‐dependent emission color change from green (493 nm) to orange (590 nm) in CH₃CN. Besides, the emission color of [(CZPY)₂IrNH]⁺PF₆⁻ is sensitive to the external electric field. Upon applying a voltage, the emission color of the complex in solution is changed evidently from orange to green at the cathode within several seconds. Moreover, with the advantages of high ionic conductivity, thermal stability, and mechanical strength, a bisimidazolium‐based polymeric ionic liquid is designed and synthesized as the electrolyte. Ultimately, a flexible electrochromic luminescence device is successfully fabricated, which exhibits excellent performance and properties, such as good flexibility, low operation voltage, fast response time, and good reversibility.