Photoluminescence properties and energy transfer of Eu3+,Bi3+ co-doped Ca9Y(PO4)7 phosphors

Abstract

Abstract：Bi 3+ and Eu 3+ ions co-activated Ca 9 Y(PO 4 ) 7 phosphors were prepared by solid-state reaction. The crystal structure, luminescence properties, and morphology of these phosphors were studied. X-ray diffraction results showed that when the calcination temperature was 1100 °C, the phosphates could obtain their own pure phase. Scanning electron microscopy images exhibited that the average particle diameter of the phosphors was approximately 5-8 μm. The phosphors could be excited by near-UV light at 397 nm, which agrees with the current UV chip, and with red light emission at 617 nm. The co-doped Bi 3+ ions demonstrated efficient energy transfer to Eu 3+ ions, and the emission intensity of Bi 3+ and Eu 3+ co-doped samples were approximately two times as high as that of Eu 3+ singly doped samples. The CIE value (0.64, 0.34) of Ca 9 Y 0.92 (PO 4 ) 7 :Bi 3+ 0.01 , Eu 3+ 0.07 was close to the standard red color coordinates. All results indicated that the red phosphors could be potentially applied to white light-emitting diodes.

Utilizing CaCO3, CaF2, SiO2, and TiO2 particles to enhance color homogeneity and luminous flux of WLEDs

“…According to Mie-scattering theory, when the SEPs in conformal phosphor pc-LEDs structure induce light scattering, at that time the effect will be determined by apply a calculating tool called MATLAB [22][23][24][25]. The equations applied to calculate the scattering coefficient μsca(λ), the anisotropy factor g(λ), the reduced scattering coefficient δsca(λ) and the scattering amplitude functions S1(θ) and S2(θ) are presented as follows:…”

Comparison of calcium carbonate and titania particles on improving color homogeneity and luminous flux of WLEDs

“…Besides that, the fabrication of HfO2/SiO2 DBR layer will make a decrease in the deviated level of color from 1758 K to 280 K at a CCT of about 5000 K [6]. Additionally, the application of remote micro-patterned phosphor film can get the color deviation decreased to 441 K at 5537 K ACCT [7]. In short, these phosphor configurations have remarkable benefits in magnifying the spatial color homogeneity.…”

The options in remote phosphor structure for better white LEDs color quality

“…Therefore, modifications such as adding more phosphor material to the remote structure are expected to bring desirable alterations and improve these optical properties of WLEDs [21][22][23]. The arrangement of phosphor layers in remote structure with two phosphor materials is yellow phosphor below red or green phosphor, while in structure with three phosphor layers the red phosphor is at the top below are green phosphor and yellow phosphor [24,25]. The concentration of phosphor layer is also an impactful element alongside model arrangement.…”