Preparation And Optical Performance Of Rare Earth Doped Luminescent Glass For White LED

In recent years,energy conservation and environmental protection is a serious problem the world have to face,green lighting and the display technique becomes a hot research direction,the white light-emitting diodes?W-LEDs?have received much attention as promising candidates to replace conventional lighting due to their long lifetime,excellent reliability,high energy conservation efficiency and environmentally friendly features.At present,the commercial W-LEDs were basically assembled from YAG:Ce3+ yellow phosphor powder and blue emitting chip by epoxy resin.The blue-emitting LED is adopted to excite yellow-emitting YAG:Ce3+ yellow phosphor.However,mechanical mixing of phosphor powder and epoxy resin can result in color spatial non-uniformity,and epoxy resin is easily oxidized at high temperature,it can makes the luminance decrease.Besides the W-LED devices show a poor and uneven color rendering index due to the lack of red-light contribution.Luminescent glasses and glass-ceramic with excellent thermal and chemical stabilities and they easy to formed in a platy shape to ensure the direct assembled with blue or UV emitting chip has been used as a potential substitute for organic polymer binders.This paper studies the main contents include the following:1.Tunable Luminescence Properties of Ce3+/Tb3+/Sm3+ co-doped CaO-B2O3-SiO2 GlassesA series of luminescent glasses Ce3+/Tb3+/Sm3+ doped CaO-B2O3-SiO2?CBS?were prepared by high temperature.melting method.The microstructure and luminescent properties of glasses were characterized with Fourier infrared spectrometer and photoluminescence spectrometer.Glasses CBS with Ce3+/Tb3+/Sm3+can emit blue,green,and red light excited at 339,378,407 nm,respectively.These emission bands just meet the requirements of hybrid synthetic white light.The emission spectra and decay c?rves of Ce3+/Tb3+ and Ce3+/Sm3 co?doped CBS glasses have proved the existence of energy transfer.The average life time of Ce3+ decreases with the increasing Tb3+ or Sm3+ concentration.At the same time,the energy transfer efficiency increases from 5.4%to 24%and 27.1%,respectively.Changing rare earth ions concentration,CIE color coordinates of Ce3+/Tb3+/Sm3+ doped glass shifts from cyan to white with increasing excitation wavelength.A white light emitting is obtained when the concentration of Ce3+/Tb3+/Sm3+ equal to 0.375%/4%/1.5%,respectively.Ce3+/Tb3+/Sm3+ doped CBS glasses demonstrates the potential application of the site engineering in advanced solid-state lighting in the future.2.Tunable colors and applications of Dy3+/Eu3+ co-doped CaO-B2O3-SiO2 glassesA series of luminescent glasses Dy3+/Eu3+ doped 47CaO-30B2O3-23SiO?CBS?were prepared by high temperature melting method.The glass samples were studied by infrared?IR?spectroscopic,density,and luminescent measurements.The prepared glass structure consists structure unit of[BO3]triangle[SiO4]pyramid and[BO4]pyramid,rare earth ions fill in the gap of glass network.Glasses CBS with Dy3+/Eu3+can emit purplish green,yellow,and red light excited at 387nm,respectively.These emission bands just meet the requirements of hybrid synthetic white light.The emission spectra and decay curves of Eu3+ co-doped CBS glasses have proved the existence of energy transfer.The average life time of Dy3+ decreases with the increasing Eu3+ concentration.Changing rare earth ions concentration,CIE color coordinates of Eu3+ co-doped glass shifts from cyan to white with increasing excitation wavelength.A white light emitting is obtained when the concentration of Dy3+/Eu3+ equal to 4%/2%,respectively.Dy3+/Eu3+ co-doped CBS glasses demonstrates the potential application of the site engineering in advanced solid-state lighting in the future.3.Tunable colors and applications of Tb3+/Eu3+ co-doped 7Li2O-7BaO-lOZnO-13Al2O3₁3B2O3-50SiO2 glassesThe Tb3+/Eu3+ ions doped 7Li20-7Ba0-lOZnO-13Al2O3-13B2O3-50SiO2 aluminoboro-silicate glasses are were prepared by high temperature melting method.Glasses with Tb3+ can emit blue,green,yellow,and red light excited at 485,540,584nm,618,respectively.color coordinates of different concentrations of Tb3+ doped glass gradually moved towards the yellow with the increasing of Tb3+ concentration.Eu 3d XPS spectrum shows the existence of Eu2+ in the samples show that some of the Eu3+ has been restored.The blue emission decreases with the increasing Eu3+concentration indicate the reduced Eu3+ gradually decreases.By adjusting the concentration of doped ions can be modulated light.A white light emitting is obtained when the concentration of Tb3+/Eu3+ equal to 7%/1%,respectively.