Phosphorescent cyclometalated Ir(III) complexes with fluoranthene unit and their near-infrared (NIR) OLEDs showing NIR% higher than 99

With the aim to design and synthesize cyclometalated Ir(III) complexes with near-infrared (NIR) emission, a series of ppy-type ligands with fluoranthene unit have been synthesized bearing different aromatic nitrogen heterocycles of isoquinoline, quinoline, pyridine and benzo [d]thiazole. With these organic ligands, four [Ir (ppy)2 (acac)] complexes are prepared named as IrFTIQ, IrFTQL, IrFTPY and IrFTBZ. In solution, IrFTIQ can emit NIR phosphorescence at 738 nm, while IrFTQL (ca. 692 nm), IrFTPY (ca. 670 nm) and IrFTBZ (ca. 690 nm) are typical deep-red emitters. It should be noted that all these fluoranthene-based cyclometalated Ir(III) complexes show good electrochemical stability indicated by their reversible redox procedures. When doped in the emission layer of OLEDs, IrFTIQ and IrFTBZ can furnish NIR electroluminescence (EL) at 748 nm and 700 nm, respectively, while the devices with IrFTPY as emitter can furnish deep-red EL. Critically, the optimized OLED doped with IrFTIQ can achieve maximum external quantum efficiency (EQE) as high as 5.01 % and a radiance up to 6284 mW Sr−1 m−2. Critically, the NIR OLEDs based on IrFTIQ can furnish EL with NIR component (NIR%) of a total spectrum > 99 %. All these encouraging results definitely demonstrate the effectiveness of our molecular design strategy for the new-type Ir(III) NIR phosphorescent complexes and the great potential of the fluoranthene group in developing high-performance Ir-based NIR phosphors for OLEDs. New fluoranthene-based phosphorescent NIR Ir(III) complexes furnishing electroluminescent efficiency of 5.01 % at 748 nm and NIR component (NIR%) of a total spectrum > 99 %. [Display omitted] •NIR Ir(III) complexes with fluoranthene group.•Fluoranthene-based phosphorescent NIR Ir(III) complexes with NIR% > 99 %.•Fluoranthene-based NIR Ir(III) complexes showing EL at 748 nm and EQE of 5.01 %.