Preparation And Properties Of White Light Macromolecular Complex Phosphor For Near UV-excited LED

Near ultraviolet white LED has become the first choice for LED lighting due to its high color rendering and controllable light color.Near ultraviolet excitated phosphor is the decisive factor for LED lighting performance.Macromolecular complexes have become the research focus of near ultraviolet excited phosphors because of their excellent luminescence properties,good mechanical properties and easy processing properties.At present,most of the studies on macromolecular complexes are focused on the direct coordination between polymer ligands and rare earth ions.This method leads to the insufficient coordination number of rare earth ions,and it is difficult for polymer ligands to achieve energy level matching with different rare earth ions at the same time,resulting in poor luminescence performance.Based on this,this paper achieved better luminescence performance by first polymerization and then coordination,and then adding small molecular ligands matching the energy level of rare earth ions.The main research results are as follows:?1?Poly?methyl methacrylate?functionalized with carboxylic acid was synthesized by copolymerization of 4-vinylbenzoic acid?p-VBA?and methyl methacrylate?MMA?.The structure and properties were characterized by ¹H NMR,FT-IR and TG-DTG.The results showed that the target macromolecular ligand is successfully synthesized,and the thermal properties of the target macromolecular ligand can meet the requirements of subsequent experiments.?2?Red light-emitting vacancy complex M₁ was prepared by coordination of Eu???ions and ligands,using alpha-thienyltrifluoroacetone?TTA?as a first ligand and 1,10-phenanthroline?phen?as a second ligand;Green light-emitting vacancy complex M₂ was prepared by coordination of Tb???ion and p-benzoylbenzoic acid?p-BBA?as the first ligand.Blue light-emitting vacancy complex M₃ was synthesized by coordination of Zn???ion and2-?2-hydroxyphenyl?benzothiazole?BTZ?as the first ligand.Subsequently,PVM-Eu-Tb-Zn was prepared by co-coordination of PVM with M₁,M₂ and M₃.Its structure and properties were characterized by FT-IR,UV-vis and fluorescence spectra.The results showed that rare earth complexes are successfully coordinated with macromolecular ligands.Under 365 nm excitation,the macromolecular complexes PVM-Eu-Tb-Zn exhibit blue,green and red characteristic emission at 449 nm,543 nm and 613 nm,and the color coordinates are?0.39,0.36?,being located in the warm white light region.LED device were fabricated by package PVM-Eu,Tb,Zn phosphor matched with 365nm near ultraviolet chip.The LED devices also exhibit red,green and blue characteristic emissions with a CCT?color temperature?of 4237 K and a CCT?color rendering index?of 83.?3?Eu???macromolecular complex PVM-Eu was synthesized with TTA as the first ligand,phen as the second ligand and PVM as the macromolecular ligand.Tb???macromolecular complex PVM-Tb was successfully synthesized by using p-BBA as the first ligand and PVM as the macromolecular ligand.The Zn???macromolecular complex PVM-Zn was prepared by using BTZ as the first ligand and PVM as the macromolecular ligand.Fluorescence spectra showed that the three macromolecular complexes exhibit red,green and blue emission characteristics,and their color coordinates are?0.637,0.329?,?0.637,0.329?,?0.287,0.598?respectively.?4?Macomolecular complexes PVM-Eu,Tb,Zn were constituted of PVM-Eu,PVM-Tb.Under 365 nm excitation,PVM-Eu,Tb,Zn exhibit characteristic emission peaks at 456 nm?blue emission?,543 nm?green emission?and 613 nm?red emission?.White light emission is realized by regulating and controlling proportion of the tricolor macromlecular complexes and excitation wavelength.Under 365 nm excitation,when PVM-Eu:PVM-Tb:PVM-Zn=15:20:1,the CIE coordinates of PVM-Eu,Tb,Zn are?0.330,0.338?,being close to the pure white light.When the ratio of tricolor phosphor is 15:20:1 and the excitation wavelength is 365 nm,the CIE coordinates are?0.330,0.338?,showing white light emission.The WLEDs device was fabricated by combining the macromolecular complex PVM-Eu,Tb,Zn with 365 nm near ultraviolet chip.The CIE coordinates?0.357,0.351?are basically consistent with photoluminescence CIE coordinates,the CCT is 4555 K,and the CRI is 87.Compared with PVM-Eu-Tb-Zn,PVM-Eu,Tb,Zn is more suitable for near ultraviolet WLEDs because of its smaller steric hindrance,easier to satisfy the coordination number of metal ions and better luminescence performance.