论文部分内容阅读
In recent years,organic near-infrared-(NIR-)emitting materials have spurred increasing interest because of their applicability in night-vision displays,sensors,and photodynamic diagnoses and therapies,etc.Among these options,transition-metal complexes are promising phosphors for organic light-emitting devices(OLEDs)[1].Of particular concern platinum complexes have been reported to realize the most efficient NIR-emitting OLEDs.However.the OLEDs based on platinum complexes generally suffer from severe efficiency roll-off.In comparison to square-planer Pt(Ⅱ)complexes,iridium(Ⅲ)complexes with typical octahedral configuration and relatively short triplet lifetime have the ability to effectively prevent intermolecular aggregation-induced emission quenching and significantly alleviate the efficiency roll-off in OLEDs devices[2].Since 2009.we have designed and synthesized a series of NIR-emitting cationic and neutral bis-cyclometalated iridium complexes with strong emission covering 690-1000 nm and good quantum efficiency.we fabricated the NIR-emitting OLEDs based on the neutral complexes with high EQEs up to 2.2%and negligible efficiency roll-off in the range of 750-900nm[3-5].In addition.we found that some cationic complexes exhibit exclusive staining in the cytoplasm with good cell membrane permeability in the desirable NIR region[6].Our work further confirmed that iridium complexes are competent alternatives for NIR-emitting OLEDs and cell imaging.