Preparation And Application Research Of Three Primary Colors Block White Polymer Phosphor Applied In Near UV-Excited LED

White light emitting diode(WLED) excited by near UV light has aroused concern since it is not affected by excitation light and has the advantages of high color rendering index and color reproduction. Bonding polymer phosphor in three primary colors phosphor applied in near UV-excited LED has become recent research hot spot because of favorable film-forming and uniform dispersion. Presently, the traditional blending inorganic phosphor has high efficiency, but it also has the defects of bad dispersion and phase separation. The three primary colors groups of polymer phosphor are randomly distributed through conventional free radical polymerization, leading to a lower luminous efficiency. Therefore, the three primary colors block white polymer phosphor was prepared through living free radical polymerization in this paper.Firstly, in this paper a green Tb(III) complex Tb(p-BBA)3UA that can match with 365 nm near UV chip was prepared. Then, Tb(III) complex Tb(pBBA)3UA and styrene monomer are polymerized to get green polymer phosphor PS-Tb. Finally, three primary colors white block copolymer phosphor PS-EuTb-Zn applied in near UV-excited LED was synthesized through the RAFT polymerization of green monomer Tb(p-BBA)3UA, red monomer Eu(TTA)2(Phen)MAA, blue monomer Zn(BTZ)UA and styrene. The conclusions are as follows :(1)A reactive Tb(III) complex Tb(p-BBA)3UA that can match with 365 nm near UV chip was synthesized with 4-benzoylbenzoic acid(p-BBA) as primary ligand and undecylenic acid(UA) as active ligand. Tb(III) complex exhibits high thermal stability and wide and strong excitation bands from 310 nm to 400 nm when monitored at 543 nm, which matches well with the 365 nm near UV chip. Meanwhile, Tb(III) complex displays Tb(III) characteristic peaks at 488, 543, 584 and 619 nm under the excitation wavelength of 365 nm. Subsequently, the intramolecular energy transfer process in Tb(III) complex was also discussed. Furthermore, Tb(III) complex displays longer fluorescence lifetime(1.317 ms) and higher quantum yield(44.8%). When used in the fabrication of LED with 365 nm near UV chip, power efficiency is 17.3 lm/W and luminance is 11110.85 cd/m2. The results indicate that Tb(p-BBA)3UA can be applied as green component for fabrication of near UV-based white LED.(2)The green polymer copolymer PS-Tb was synthesized with Tb(III) complex Tb(p-BBA)3UA and styrene as ingredients. IR and UV spectra analyses show that Tb(III) complex Tb(p-BBA)3UA and styrene have already successfully polymerized. Fluorescence analysis indicates that the optimal emission peak of polymer copolymer PS-Tb, located at 543 nm, are consistant with Tb(III) complex. With respect to Tb(III) complex, intensity of optimal emission peak of polymer copolymer PS-Tb enhances by 11.5%. Thermal analys is shows that compared with Tb(III) complex, the initial decomposition temperature of polymer copolymer PS-Tb rises by 81℃. This indicates that polymer copolymer PS-Tb can meet the need of operation temperature of LED better.(3)The three primary colors white block copolymer phosphor PS-EuTb-Zn applied in near UV-excited LED was synthesized through the RAFT polymerization of green monomer Tb(p-BBA)3UA, red monomer Eu(TTA)2(Phen)MAA, blue monomer Zn(BTZ)UA and styrene. Thermal and fluorescent analyses indicate that the copolymer PS-Eu-Tb-Zn displays favorable thermal stability and luminescence properties. When excited at 365 nm, the copolymer PS-Eu-Tb-Zn exhibits emission peaks at 421 nm(blue emission of Zn(II) complex), 488, 543 nm(green emission of Tb(III) complex), 589 and 615 nm(red emission of Eu(III) complex). Two methods of the copolymer PS-Eu-Tb-Zn to realize white light(tuning the ratios of red, green, blue three kinds of monomers and adjusting excitation wavelengths) are discussed. The CIE coordinates of the copolymer PS-Eu-Tb-Zn is(0.352, 0.33) upon excitation at 365 nm, which is close to pure white light. For the fabricated white LED device using a 365 nm near UV chip with the copolymer PS-Eu-TbZn phosphor, the CCT is 5684 K, and the CRI is 83.1. All the results indicate that the copolymer PS-Eu-Tb-Zn can be applied as white phosphor for the fabrication of near UV-based LED.