Application Of Three - Color Phosphor Based On Near - Ultraviolet Excitation In AC

Nowadays, LED device driven directly by alternating current（AC） has become the focus of research to generate light. Therefore, to explore phosphors suited for AC-LED has gradually attracted more and more attention. However, the categories of phosphors applied to AC-LED were limited. Meanwhile, The afterglow time of these phosphors are not match with the period of alternating current. Due to the periodic cycle of alternating current, the fabricated LED will cause a series problems, such as flickering, variable color, low color rending index, etc. In this paper, it is aim to seek red, green and blue afterglow phosphors, which can be fabricated with Ga（In）N near ultraviolet LED to obtain white AC-LED. Rare earth ions doped aluminates are synthesized due to good thermal stability and chemical stability. The effects of flux, types of rare earth ion and elements of host on size and distribution of particle, morphology, crystal structure and luminescence properties were systematic studied. Moreover, red Sr₂Si₅N₈: Eu²⁺ phosphors were successfully synthesized by a novel method. Following is the main work:1. SrAl₂O₄: Eu²⁺, Dy³⁺ phosphors were prepared by the high temperature solid state method, and SrCl₂ was used as fluxes to improve the optical performance of SrAl₂O₄: Eu²⁺, Dy³⁺ phosphors. The influence of the weight ratio of SrCl₂ on the morphology, optical properties and decay of SrAl₂O₄: Eu²⁺, Dy³⁺ phosphors were investigated in details. The electroluminescent properties of LEDs with SrAl₂O₄: Eu²⁺, Dy³⁺ phosphors were also studied. It is revealed that SrCl₂ is an excellent candidate for flux to improve the optical performance of SrAl₂O₄: Eu²⁺, Dy³⁺ phosphor.2. Based on the chemical unit cosubstitution, SrAl_2-xSi_xO_4-xN_x: Eu²⁺, Dy³⁺ phosphor doped with different amount of（SiN）⁺ were synthesized. The chemical stability and the color purity of SrAl₂O₄: Eu²⁺, Dy³⁺ were improved. The solubility and the effect of the（SiN）⁺ on the crystal structure, photoluminescence property, decay time and their correlation in SrAl_2-xSi_xO_4-xN_x: Eu²⁺, Dy³⁺ phosphors are discussed systematically. Furthermore, the electroluminescent property of pc-LEDs based on UV-chips and these phosphors are also studied.3. A series Sr_0.9-xCa_xAl₂O₄: Eu²⁺, Dy³⁺ and Sr0.9-xBaxAl2O4: Eu²⁺, Dy³⁺ phosphors with different Ca/Sr or Sr/Ba ratio were synthesized by the high temperature solid-state method. The tunable emission color and average lifetime of SrAl₂O₄: Eu²⁺, Dy³⁺ phosphors were studied, and the blue CaAl₂O₄: Eu²⁺, Dy³⁺ phosphor can be obtained. The effect of the content of Ca²⁺ or Ba²⁺ on phase structural, optical properties and decay time of SrAl₂O₄: Eu²⁺, Dy³⁺ phosphors were discussed. Further more, the electroluminescent property of as-fabricated LEDs based on UV-chips and SrAl₂O₄: Eu²⁺, Dy³⁺ phosphors were also studied.4. A novel synthesis technology, named pellet method, was firstly applied to prepare the red Sr₂Si₅N₈: Eu²⁺ phosphor. This method need not use nitrides with the oxygen and moisture sensitivity as raw materials, which can avoid using the glove box. The influence of Eu²⁺ ion concentration on phase, particles size, photoluminescence properties of Sr₂Si₅N₈: Eu²⁺ phosphor were researched. And the concentration quenching process among Eu²⁺ ions were investigated in details. Finally, the red LEDs is successfully prepared by using prepared Sr₂Si₅N₈: Eu²⁺ phosphor combined with UV-chips and the electroluminescent properties of red LEDs were also studied.