| Phosphor-converted white light-emitting diodes (pc-LEDs) are expected to replace incandescent lamp, fluorescent lamp, sodium lamp and become a new generation of lighting source due to their unique properties including but not limited to energy saving, environment-friendliness, small volume, long persistence, short start time, and stable structure. So far, primary challenges in pc-LEDs have been to attain high luminous efficacy, brilliant color-rending properties, and price competitiveness against fluorescent lamps, which rely crucially on the properties of phosphors.Phosphors are key material for white-LEDs. As the traditional phosphor material, YAG:Ce3+ shows poor color rendition and low thermal stability. Recently, CaSi2O2N2:Eu2+ phosphors have been proved to be excellent phosphors for white-LED lighting application because of their outstanding luminescent properties, high thermal and chemistry stability, and well matching property with LED chip. However, the luminescent intensities of these phosphors still need to be further improved for practical applications.In this paper, Eu2+ and Pr3+, Nd3+, Sm3+, Tb3+ or Dy3+ co-doped CaSi2O2N2 phosphors were prepared through high-temperature solid-state reaction. The phosphors were characterized by X-ray diffraciton (XRD), fluorescence spectrophotometer (PL) and solid quantum efficiency (QE). XRD patterns revealed that the samples maintain CaSi2O2N2 single phase after co-doping rare earth ions. The PL results showed that the emission intensity can be greatly enhanced through doping Dy3+ or Tb3+ in CaSi2O2N2:Eu2+ phosphors. Li+ ions could be used as charge compensation in CaSi2O2N2:Eu2+, Dy3+ phosphors. Thus the doping of Li+ ions could further improve the emission intensity of CaSi2O2N2:Eu2+,Dy3+ phosphor. And the emission intensity of phosphor greatly relied on the concentration of Dy3+ and Li+. When the doping concentration of Dy3+ and Li+was up to 1 mol%, the emission intensity reached maximum, and the quantum efficiency of this phosphor was 61.06%.Doping non-rare-earth ions into phosphors can also improve the emission intensity of phosphors. In this paper, Mg2+ doped CaSi2O2N2:Eu2+ phosphors were prepared through high-temperature solid-state reaction. The results showed that doping Mg2+ could remarkably enhance the emission and the absorption intensity of phosphors. This novel phosphor also has high thermal stability and high quenching concentration. It is a very promising phosphor for white LEDs applications. Moreover, the phosphors were modified by y-MPS and the settlement in epoxy resin of phosphor was improved after modification.For further developing new phosphor using in white LED, Eu ions doped Ca4Si2O7F2 phosphor s were prepared via carbothermal reduction method. The preparation technology of this kind of phosphor was preliminary explored and the influence of sinter temperature and the content of H3BO3 in raw materials on the luminescence performance of samples were studied. The experimental results showed that the single Ca4Si2O7F2 phase was obtained when the content of H3BO3 was 20 wt% and the sinter temperature was 900℃and 1000℃. The samples obtained at 900℃emitted red light under the excitation of 400 nm. |
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