Srudy On White LED Of Fluorescence Tuned By Spectrum

WLEDs have been widely used in lighting,display,and many other fields due to its high light efficiency,energy saving,environmental protection,all-solid-state,design diversity,long working life,and many other advantages.Application performance of efficiency,color temperature,stability and color rendering index of WLEDs are depending on luminescent materials.Therefore,developing the WLEDs of new luminescent materials have important practical significance.In this thesis,a series of single-doped Ca₉Y?PO₄?₅?SiO₄?F_1.5O_0.25:Ln³⁺(Ln³⁺ = Eu³⁺/Tb³⁺/Dy³⁺/Sm³⁺)new luminescent materials have been prepared via the conventional high-temperature solid-state reaction.The structure refinement,photoluminescence properties,and decay curves were studied in detail.Under near-UV excitation,the Ca₉Y?PO₄?₅?SiO₄?F_1.5O_0.25:Eu³⁺/Tb³⁺/Dy³⁺/Sm³⁺ phosphor shows characteristic emission of the Eu³⁺?5D0-7F2,red?,Tb³⁺?5D4-7F5,green?,Sm³⁺?4G5/2-6H7/2,red?,and Dy³⁺?4F9/2-6H13/2,yellow?,respectively.The emission intensities of Ca₉Y?1-x/z??PO₄?₅?SiO₄?F_1.5O_0.25:xEu³⁺/zSm³⁺ reach maximum when x = 0.16 and z = 0.10,respectively,and the concentration quenching mechanisms are both dominated by dipole–dipole interactions.The excitation spectra of Ca₉Y?PO₄?₅?SiO₄?F_1.5O_0.25:Eu³⁺/Sm³⁺ phosphors show the strongest absorption at about 400 nm,which matches well with the commercially available near-UV-emitting InGaN-based LED chip.The red light emitting-diodes?LEDs?lamp was fabricated using the as-prepared Ca₉Y?PO₄?₅?SiO₄?F_1.5O_0.25:Eu³⁺/Sm³⁺ phosphor and commercial near-UV-emitting InGaNbased LED chip.It indicates that Ca₉Y?PO₄?₅?SiO₄?F_1.5O_0.25:Ln³⁺ could be a promising phosphor for white LEDs.