The study uses the green phosphor of Ca2SiO4:Eu2+ to achieve the color constancy for the dual-film remote phosphor white-LED model at low as well as big CCTs. The utilized green phosphor Ca2SiO4:Eu2+ was prepared using the water-soluble-silicon liquid phase precursor method with the doped Eu2+ ion concentration of 3 mol%. The Ca2SiO4:Eu2+ phosphor emits strong green light with emission intensity focused at 502 nm wavelength, and a wide stimulation band of colors of 225 nm – 450 nm. After applying the Ca2SiO4:Eu2+ green phosphor and modifying its concentration, the modified color and luminous performances can be observed. The better color uniformity and higher luminescence efficiency can be obtained by increasing the percentage of Ca2SiO4:Eu2+ in the phosphor configuration. Meanwhile, the color rendering metrics tend to reduce slightly when the concentration of Ca2SiO4:Eu2+ is over 10% wt.
This study compares red-phosphor LaOF:Eu 3+ impacts on a single-film remote phosphor configuration (SRPC) and a double-film remote phosphor configuration (DRPC). Mie theory is used to demonstrate the relationship between light flux and color quality. SRPC is a phosphor layer consisting of LaOF:Eu 3+ particles mixed with YAG:Ce 3+ . Meanwhile, DRPC is two separate films of red and yellow phosphors. To increase scattering properties, we added 5% SiO2 into phosphor layers. The differences in structure affect significantly white light emitting diodes' (WLEDs') optical properties. Attained figures and statistics show that the color rendering indices (CRIs) increase along with the concentrations of both structures, and these numbers are approximately similar. However, DPRC exhibits a color quality scale (CQS) of 74 in all examined chromatic temperatures (5600 K − 8500 K), which is greater than SRPC's 71 at 8500 K. Besides, the luminous efficiencies (LEs) in DRPC are more outstanding than that of SRPC, at given LaOF:Eu 3+ concentration percentages (2%−14%). To summarize, DRPC offers greater benefits in luminous flux and color quality, compared to SRPC. Choosing the proper red light phosphor concentration, on the other hand, becomes a crucial aspect of achieving the ideal CQS and LEs.
This research combines a phosphor-in-glass (PiG) YAG:Ce3+ with a red liquid-type quantum dot (LQD) to invent high-quality white light-emitting diodes (WLEDs). When the PiG LQD-built WLEDs reach 100 mA, they provide heated white illumination offering an outstanding color rendering index (CRI) (Ra=93.9, R9=97.7, and R13=98.1). The luminescent efficiency (LE) and correlating chromatic temperature, correspondingly, are 62 lm/W and 3764 K. In comparison to PiG integrated with solid-kind quantum dot, it has great LE, remarkable CRI, and lower top layer temperature because of self-aggregation and impediment in the outside flaws in semiconductor quantum dots (QDs) of the solid-condition, as well as effective thermal dissipation. The findings suggest that the produced WLEDs could be potential in high-quality lighting applications.
The study <span>investigated the effectiveness of coating silica nanoparticles (SiO<sub>2</sub>) and resin-silica nanocomposites poly methyl methacrylate (PMMA)-silicaover the surface of Y<sub>2</sub>O<sub>2</sub>S:Eu<sup>3+</sup> red phosphors. The purpose of this surface coating is to enhance the optical properties, including the photoluminescence (PL) and long-term stability, of Y<sub>2</sub>O<sub>2</sub>S:Eu<sup>3+</sup>. Two methods used to coat the phosphor with 5-mm silica nanoparticles are dip-coating and sol-gel (Stöber) methods. SiO<sub>2</sub> nanoparticles were formed via hydrolysis and condensation reactions, while radical polymerization was performed to fabricate the poly (1-vinyl-2-pyrrolidone). The Y<sub>2</sub>O<sub>2</sub>S:Eu<sup>3+ </sup>surface coating of PMMA-silica composite was performed via two reactions. One is the reaction of SiO<sub>2</sub> nanoparticles with methyl methacrylate (MMA) monomer, and the other is MMA-tetraethyl orthosilicate (TEOS) reaction. The results showed that by using the latter method, Y<sub>2</sub>O<sub>2</sub>S:Eu<sup>3+</sup> yielded better PL and long-term stability. Additionally, surface coating with the PMMA-SiO<sub>2</sub> nanocomposite using the second technique resulted in 5% enhancement in PL and stabilized the cathode luminescence (CL) intensity of Y<sub>2</sub>O<sub>2</sub>S:Eu<sup>3+</sup>, compared to those properties of uncoated Y<sub>2</sub>O<sub>3</sub>S:Eu<sup>3+</sup> phosphor particles.</span>
<span>The use of (Ba,Sr)<sub>3</sub>BP<sub>3</sub>O<sub>12</sub>:Eu<sup>2+</sup> in the remote phosphor structure has been proposed and analysed to offer significant improvement to the lighting performance of the phosphor-converted white light emitting diode (LED). The phosphor emits green and blue spectra centred at 520 nm and 465 nm, respectively. Thus, the phosphor can compensate the blue and green light energy components in the white-light spectral band, helping to enhance the luminous efficiency and colour uniformity of the dual-layer remote phosphor package. The increase in (Ba,Sr)<sub>3</sub>BP<sub>3</sub>O<sub>12</sub>:Eu<sup>2+</sup> however is not advantageous to the colour rendering index because of the lower red emission. The backscattered and back-reflected lights are degraded when the (Ba,Sr)<sub>3</sub>BP<sub>3</sub>O<sub>12</sub>:Eu<sup>2+</sup> phosphor layer appears in the structure. The stable chromaticity and luminous flux at good values are observed when 10% weight percentage of (Ba,Sr)<sub>3</sub>BP<sub>3</sub>O<sub>12</sub>:Eu<sup>2+</sup> is applied</span>.
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