Solution concentration-dependent tunable emission in cyclometalated iridium complex bearing perylene diimide (PDI) ligand: From visible to near-infrared emission

Abstract To explore the multicolor photoluminescence switching in perylene diimide (PDI) derivatives, a PDI-based iridium complex of (ppy) 2 IrPDI was prepared and characterized by NMR, MS and elemental analysis. This iridium complex showed clearly concentration-dependent emission spectra in solution, which is generated from different excited states (singlet and triplet), as evidenced by experimental and theoretical methods. Conversely, the iridium complex presented phosphorescent near-infrared emission (∼750 nm) both in neat film and in a solid-state polymethylmethacrylate (PMMA) matrix. This research provides another way to access the radiative emission from triplet states of PDI derivatives, which has an important significance for further understanding the photophysics of the PDI based phosphorescent complex.