Synthesis And Optoelectronic Property Of PVK-Supported Ir³⁺-Containing Metallopolymer With Near-Infrared Luminescence

Near-infrared（NIR）emissive Ir³⁺-complexes have attracted much attention due to their good stability,high luminous efficiency,and microsecond-graded phosphorescence lifetime.Further from the viewpoint of the NIR polymer light-emitting diode（NIR-PLED）application of their physical doping into organic polymers,the problems of low NIR electroluminescent efficiency and severe efficiency-roll-off caused by phase separation and aggregation-induced quenching are actually faced.Toward the solution to those above-mentioned‘bottle-neck’questions,this thesis focuses on an approach to the covalently-grafting of the NIR-emitting Ir³⁺-complexes into the organic polymer backbone for the realization of molecularly uniform dispersion of the NIR-chromophores.Moreover,under the conditions of both high NIR luminescence and good physical property,their NIR-PLED devices are fabricated,which should give a new strategy to future NIR-PLEDs.The main research contents are as follows:In part one,using the rigid nitrogen heterocyclic ligand Hiqbt（1-（benzo[b]thiophen-2-yl）isoquinoline）as the HC^N main ligand and the vinyl-functionalized Schiff-base ligand4-VB-HPLP（（E）-4-（4-vinylbenzene）-2-（（phenylimino）methyl）phenol）or3-VB-HPLP（（E）-4-（3-vinylbenzene）-2-（（phenylimino）methyl）phenol）as the HN^O-typed auxiliary ligand,two new NIR-emitting Ir³⁺-complexs[Ir（iqbt）₂（4-VB-PLP）]and[Ir（iqbt）₂（3-VB-PLP）]are obtained,respectively.Upon the structure characterization,the mechanism to their NIR luminescence is specially studied.In part two,considering the excellent physical properties and strong hole-transport ability of PVK（polyvinylcarbazole）,the NIR-emitting vinyl-functionalized Ir³⁺-complex monomer[Ir（iqbt）₂（4-VB-PLP）]was copolymerized with NVK（vinylcarbazole）through a free radical polymerization procedure,from which,the novel grafting-typed hybrid material Poly（NVK-co-[Ir（iqbt）₂（4-VB-PLP）]）with desirable NIR luminescence is obtained.On the other hand,using the doping-typed hybrid material of[Ir（iqbt）₂（4-VB-PLP）]into PVK or that grafting-typed Poly（NVK-co-[Ir（iqbt）₂（4-VB-PLP）]）as the light-emitting layer for comparison,their solution-processed NIR-PLEDs are realized,respectively.Finally,in order to further clarify the significance of grafting of the NIR-chromohores（[Ir（iqbt）₂（3-VB-PLP）]）for the improved electroluminescent performance,two kinds of copolymerization methods,such as conventional free radical polymerization and reversible addition-fragmentation chain transfer（RAFT）radical polymerization are specially compared.Uopn the realization of their solution-processed NIR-PLEDs,the relationship of the copolymerization procedure on the electroluminescent performance is also investigated.