Synthesis And Luminescent Properties Of UV Resistant Eu-polymer Phosphors

The red-emit phosphor,as component of white phosphor in near ultraviolet excited LED,takes more attention on account that it can adjust the color temperature and improve color rendering.Meanwhile,Rare earth ions have the characteristics of fixed wavelength,narrow red emission and so on,which become the preferred materials of LED red phosphors.Due to the near ultraviolet long-term irradiation on the phosphor and packaging materials,the lifetime of LED device is significantly reduced.In order to improve the luminous efficiency and optical output power of near ultraviolet excited LED,it is required that the packaging materials possess good UV resistance and refractive index.Organic silicone is one of the most promising materials for packaging materials because of its inorganic/organic structure,weather resistance,anti ultraviolet property and refractive index.In this paper,the rare-earth polymer phosphors were synthesized by solution polymerization method that the Eu?III?reactive complex was bonded to the UV resistant organosilicon polymer chain.The aim is to improve the anti-ultraviolet property and the refractive index of the phosphors,thereby improving the durability and luminous flux of LED devices.1)Copolymer P-Eu-Si was synthesized by reactive Eu-complex Eu?TTA?₂?Phen?MAA and trimethoxy?4-vinylphenyl?silane monomer,which can be used for UV excited red-emit phosphors.The fluorescence analysis of thecopolymer shows the best excitation wavelength is 333 nm and a pure red emission at 613 nm is related to the ⁵D₀?⁷F₂ transition of Eu3+.The absolute fluorescence quantum yield is 63 %.The fluorescence lifetime is 0.586 ms,with a loss of 0.003 ms after UV aging for 150 h.The packaged LED devices have excellent luminescent properties.The CIE is?0.625,0.308?,which located in the red region.At the same time,compared with the Eu-complex,the attenuation of brightness is greatly reduced,which indicating that it has certain UV resistance.2)The polymer red phosphor PM-Eu-Si was synthesized by introducing methyl methacrylate monomer.The results show that the excitation wavelength of polymer phosphor is between 355--370 nm and strongest characteristic emission of Eu³⁺ peaked at 612 nm,which matches well with the 365 nm near UV chip..The fluorescence lifetime is 0.589 ms,with a loss of 0.006 ms after UV aging for 150 h,shows certain UV resistance.The packaged LED devices have good luminescent properties,CIE color coordinate is?0.60,0.32?,located in the red area.The brightness attenuation is small,indicating it has a certain degree of UV resistance and high transmittance.3)First of all,the novel organic silicon material was prepared by sol gel method with trimethoxy?4-vinylphenyl?silane,?-?2,3-epoxypropoxy?propyl trimethoxysilane?KH-560?and diphenyl silanediol.And then,the polymer red-emit phosphor P-Eu-Si-Ph with high brightness was obtained by polymerization with the Eu-complex and synthetic organic silicon.The prepared polymer phosphor has an excitation band in the near ultraviolet wavelength of345--365 nm,emission peak of Eu?III?ions at 612 nm,and the fluorescence intensity is up to 2.8×10⁷ a.u..Thermal analysis shows that the initial decomposition temperature is 170?,which can meet the requirement of LED operating temperature.LED devices exhibit excellent luminescent properties.The luminous flux is 1.555 lm,and the brightness attenuation is extremely small.Indicating polymer P-Eu-Si-Ph possesses excellent luminous flux and UV resistance.