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Modulating the Excited-State Properties of Iridium(III) Complexes for Achieving Narrowband Deep-Red/Near-Infrared
Xiang-Zeng Wang1, Meng-Xin Xu2, Li-Li Wen1
1School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, Jilin Provincial International Joint Research Center of Photo functional Materials and Chemistry, Jilin Provincial International Joint Research Center of Photofunctional Materials and Chemistry, Changchun University of Science and Technology, Changchun 130022, P. R. China.
None:
Developing near-infrared (NIR) iridium(III) complexes with a narrowband emission remains a critical challenge for organic light-emitting diode (OLED) applications. Herein, two structurally simplified complexes, QT-Ir-Me and QT-Ir-tBu, featuring rigid cyclometalated ligands, are successfully developed. Both complexes exhibit deep-red/NIR phosphorescence with emission maxima at 692 nm for QT-Ir-Me and 706 nm for QT-Ir-tBu, with exceptionally narrow full width at half-maximum (FWHM) of 47 nm in a dilute solution. The suppressed spectral broadening can be assigned to dominated triplet ligand-centered charge transition in the excited state and constrained structural distortion, corroborated by minimal root-mean-square deviation of 0.089 and 0.084 for QT-Ir-Me and QT-Ir-tBu, respectively. Moreover, QT-Ir-Me and QT-Ir-tBu exhibit high photoluminescence quantum yields of 53% and 28%, respectively. The doped devices employing QT-Ir-Me and QT-Ir-tBu as emitters exhibit narrowband deep-red/NIR luminescence with FWHMs of 60 and 58 nm, respectively. A QT-Ir-Me-based device demonstrates higher electroluminescence performance with a maximum external quantum efficiency of 6.3%.
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