- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Ultraviolet to blue blocking and wavelength convertible films using carbon dots for interrupting eye damage caused by general lighting
摘要： Our eyes are regularly exposed to ultraviolet (UV) and blue light emitting diode (LED) light-based devices. However, the blue light induces macular degeneration, optic nerve crush, eye strain, and increases reactive oxygen species, which negatively influence eye-related cells (photoreceptor and retinal pigmented epithelial cells). UV light is also harmful to humans. It induces photokeratitis, cataract, and ocular surface squamous neoplasia. Here, we present carbon dot films with different carbon dot contents, prepared by a simple method. The films exhibit strong UV and blue light absorption. The transmittance of carbon dot films is >70% in the visible region (>500 nm). The UV light blocking ratio of commercial blue blocking filter and carbon dot film using UV LED chips is 94.1% and 95.9% (40 wt%), respectively. The blue light blocking ratio of commercial blue blocking filter and carbon dot film using blue LED chips is 10.2% and 82.3% (40 wt%), respectively. These results indicate that the prepared carbon dot films have a UV blocking rate similar to that of commercial blue blocking filters and a much better blue blocking rate than commercial blue blocking filters. Therefore, they can be effectively used as UV and blue blocking films in various applications.
关键词： White LED,Eye damage,UV blocking film,Carbon dot,blue blocking film
更新于2025-11-14 15:15:56
-
Structure variation and luminescence enhancement of BaLaMg(Sb, Nb)O6:Eu3+ double perovskite red phosphors based on composition modulation
摘要： A series of BaLaMgSb1-xNbxO6:Eu3+ double perovskite red phosphors was successfully obtained. X-ray diffraction and Rietveld refinement analyses were conducted to determine the phase information and the detailed structure parameters. The coordinate variations of both La3+/Eu3+ and Sb5+/Nb5+ were discussed to elucidate the influence of B-site ion doping on the lattice variation. Luminescence properties, excitation and emission spectra, were presented to show the advantages of doping with Nb5+ ion. Ultraviolet-vis diffuse reflectance spectra were performed to reveal the reason for the decreased emission intensity under the charge transfer band excitation. Moreover, band gap energy was estimated to clarify the relationship between the increased intensity (λex = 395 and 465 nm) and Nb5+ concentration. Intensity ratios of I(615)/I(590) were performed to show the symmetry variation of the lattice. Thermal quenching property was also investigated and the quenching mechanism was discussed in detail based on the ionization process.
关键词： White LED,Structure variation,Thermal quenching mechanism,Double perovskite
更新于2025-09-23 15:23:52
-
Near White Light Emission and Concentration Quenching of Calcium Titanate Doped with Dysprosium (III) Phosphors
摘要： This paper reports the preparation of CaTiO3 doped with various concentrations of Dysprosium (II) using solid state reaction technique. X-ray diffraction patterns of the sample were taken. Observed XRD pattern was matched using software match2!. The pattern was matched significantly with the crystallographic open database card (COD – 96-101-1212) which is a standard card for CaTiO3. This matching exhibited that, the prepared sample is cubic in structure with space group P m ? 3 m (221). Photoluminescence (PL) studies of the samples were also done. PL intensity was found increasing with increasing dopant concentration and maximum intensity was noted at 2.0 mol% concentration of Dy3+, thereafter concentration quenching occurred. Emission Peaks were centered at 483 nm (4F9/2?6H15/2) and 576 nm (4F9/2?6H13/2) respectively. For studying the concentration quenching, the critical distance for energy transfer and electric multipolar character were estimated. The value of multipolar character expressed that, the transition in emission spectra is a dipole – dipole (d-d) transition. Commission Internationale de l’éclairage (CIE) coordinates was found as (0.36, 0.39), which is near to white light. Colour Correlated Temperature (CCT) was 4489 K which was indicative of cool appearance of the light emitted.
关键词： White LED,Concentration quenching,Photoluminescence
更新于2025-09-23 15:22:29
-
Synthesis and photoluminescent properties of Ba2+ ions doped europium formate phosphors for white light-emitting diodes
摘要： We report on the synthesis and photoluminescent performance of the Ba2+ ions doped Eu(HCOO)3 phosphors as well as their promising applications in indoor illumination. The thermal stability of the synthesized sample with microparticles was characterized by the thermogravimetric analysis. Irradiated by 396 nm light, the unique emissions of Eu3+ ions originating from the 5D0 → 7FJ (J ? 1, 2, 3, 4) transitions were observed. With the aid of the Judd-Ofelt theory, the local symmetry properties of the Eu3+ ions in the selected host were studied, revealing that the sites taken by the Eu3+ ions possessed low symmetry with non-inversion center. An enhanced luminescent intensity was seen in the resultant phosphors when the Ba2+ ions were introduced and the optimal doping content was 10 mol%. The studied samples can exhibit bright visible red emission with high color purity of 93.3% upon 396 nm excitation. Moreover, the resistance of the emission intensity to the temperature was also explored and the activation energy was 0.188 eV. Furthermore, the internal quantum efficiency of the resultant samples was 67% when excited by 396 nm. Ultimately, a light-emitting diode (LED) lamp, which emitted warm white light with high color rendering index of 80.7 and low color correlated temperature of 4715 K, was constructed, indicating the feasibility of the synthesized phosphors for white-LED.
关键词： Phosphors,White-LED,Luminescence,Rare-earth ion
更新于2025-09-23 15:21:01
-
A Novel Highly Efficient Hosta??Sensitized Red Emitting (Ba <sub/>2</sub> YV <sub/>3</sub> O <sub/>11</sub> a??:a??Eu <sup>3+</sup> ) Phosphor for Hybrid White LEDs
摘要： The present investigation focused on the sequence of Eu3 + activated red-emitting vanadate phosphor for the high performance white LEDs. The blue emitting host lattice (Ba2YV3O11) and red emitting Ba2YV3O11 : Eu3 + phosphors were synthesized by the conventional solid-state method and studied their optical properties in details. The host lattice and Eu3 + activated red phosphors were crystallized in the monoclinic crystal system. The Ba2YV3O11 emission was found in the bluish-green region (444 and 512 nm, which corresponds to the 3T2!1A1 and 3T1!1A1 transitions), and the Eu3 + activated phosphors (Ba2Y1-xEuxV3O11, x = 0-1, insteps of 0.1) display intense red emission at 618 nm due to the 5D0!7F2 electric dipole (ED) transition. The concentration quenching was observed at x = 0.6, the detailed energy transfer mechanism was also explored. Thermal stability of the Ba2Y0.4Eu0.6V3O11 red phosphor retains the ～ 60 % emission intensity at 423 K, and the internal quantum efficiency (IQE) was found to be 30 %. The red and white LEDs were fabricated by using the synthesized red phosphor with the combination of near UV LED (n-UV), the white LED showed white emission with CIE is x = 0.359; y = 0.395; higher CRI (89) and low CCT (4693 K) values. These results prescribe that the presently synthesized phosphor can act as a suitable red-emitting component in hybrid white LEDs.
关键词： Vanadates,High CRI,Charge transfer,White LED,IQE
更新于2025-09-23 15:21:01
-
Novel red emitting LnTaO4: Eu3+ (Ln = La, Y) phosphors for warm white LEDs
摘要： LnTaO4: Eu3t (Ln ? La, Y) phosphors were synthesized by high-temperature solid-state reaction. Powder X-ray diffraction analysis confirmed the pure phase formation. Diffuse reflection spectra, excitation and emission spectra, the CIE chromaticity coordinates as well as the temperature-dependent emission spectra were investigated those phosphors. Upon near UV and blue excitation LnTaO4: Eu3t (Ln ? La, Y) show intense red emission of Eu3t. The optimum concentration of Eu3t in LaTa1-xEuxO4 phosphor was x ? 0.20, and concentration quenching mechanism was the electric dipole-dipole interaction. Furthermore, the critical transfer distance was obtained and the CIE chromaticity coordinates of LaTaO4: Eu3t samples were close to the National Television System Committee standard values. The temperature-dependent luminescence indicated LaTaO4: Eu3t exhibited moderate thermal stability. Those results suggested that LnTaO4: Eu3t (Ln ? La, Y) as red emitting phosphors could be potential candidates for white LEDs.
关键词： Luminescent properties,Red emitting phosphors,White LED,Thermal stability
更新于2025-09-23 15:19:57
-
High performance red/deep-red emitting phosphors for white LEDs
摘要： Highly efficient oxide based red line emitters are still bottleneck for the smart white LEDs. In the present investigation, sequences of narrow band red emitting phosphors were synthesized through the conventional solid-state technique. The X-ray diffraction studies reveals that the synthesized phosphors were crystallized in the trigonal phase with space group I41/a (88). Under 395 nm excitation, NaSrGd(MoO4)3:Eu3+ phosphors shown sharp red emission around at 616 nm because of the 5D0→7F2 transition (ED transition). Moreover, the internal quantum efficiency (IQE) was found to be 82 %, and the thermal stability study showed that the NaSrGd0.5Eu0.5(MoO4)3 phosphor retains the emission intensity around 71.5% at 423K of its initial room temperature. The red LEDs were designed for the NaSrGd0.5Eu0.5(MoO4)3 red phosphors with the NUV LED chip. White LED also been fabricated by conjugating the blue LED with yellow dye + red phosphor and the LED shown CCT (6823 K), CRI (74%), CIE (0.306, 0.331). The Sm3+ and Eu3+ co-doped deep red phosphor were synthesized and studied for the plant growth. The LED emission of Sm3+ and Eu3+ co-doped phosphor is completely covers the absorption spectrum of Phytochrome Pr. All of these consequences revealed that the synthesized phosphor could be the efficient red emitting phosphor for warm white LEDs and plant growth filed research.
关键词： Eu3+ red phosphor,Quantum Yield,White LED,Plant growth,Molybdate
更新于2025-09-23 15:19:57
-
Al2O3-Ce:GdYAG composite ceramic phosphors for high-power white light-emitting-diode applications
摘要： In order to meet the increasing demand of high-power light-emitting-diode (LED) lighting, state-of-the-art white light-emitting diode technology needs phosphors with high thermal conductivity and high luminous efficacy as color converters. In this work, translucent Al2O3-Ce:GdYAG composite phosphors were prepared by solid-state reactive sintering. The microstructure shows that the Al2O3 particles are uniformly dispersed in the Ce:GdYAG matrix. These particles can not only improve the thermal conductivity of the ceramics, but also promote the extraction efficacy. The luminous characteristics of the Ce:GdYAG and Al2O3-Ce:GdYAG ceramics were analyzed after being packaged with blue LED. When the molar ratio of Al2O3/Ce:GdYAG is 0.8, a high luminous efficacy value of 112.6 lm/W is achieved by the Al2O3-Ce:GdYAG composite ceramic phosphor with the thickness of 0.4 mm, as well as the highest CRI valve of 71.4. The appropriate photoelectric properties of this kind of ceramic phosphor make it a promising candidate for high-power LED device.
关键词： luminous efficacy,white-LED,color coordinates,composite ceramic phosphors,Al2O3-Ce:GdYAG
更新于2025-09-19 17:15:36
-
High staility of silica-wrapped CsPbBr3 perovskite quantum dots for light emitting application
摘要： Encapsulating quantum dots (QDs) into other medium has been considered as an efficacious method to avoid the fluorescence degradation of QDs. Here, we proposed a facile method to embed CsPbBr3 perovskite QDs in silica matrix derived from (3-aminopropyl)triethoxysilane (APTES) at room temperature in open air. The QDs/SiO2 composite was extracted from the sol-gel solution by using a precipitation-encapsulation method assisted with APTES. As-prepared composite powder possess a high photoluminescence quantum yield (PLQY) of 68% and a full width at half maximum (FWHM) of ~23 nm. The QDs/SiO2 compounds show excellent stability after the five heating cycles (105 °C) and a continuous xenon irradiation (500 W, 70 °C). Besides, the products remain 94.3% and 98.6% photoluminescence (PL) intensity after 30 days of storage (25 °C) and 96 hours of ultraviolet (UV) irradiation (λ= 365 nm) respectively. The white light-emitting diode (LED) was fabricated by coating green-emitting CsPbBr3@SiO2 composite powder and commercial red phosphors on blue chip. The fabricated white LED performed excellent light characteristics with a luminous efficacy (ηL) of 58.9 lmW-1 and a correlated color temperature (CCT, Tc) of 5829 K (current = 20 mA), it also display a wide color gamut with 126.8% of National Television System Committee (NTSC) color triangle area.
关键词： white LED,stability,perovskite QDs,CsPbBr3,SiO2
更新于2025-09-19 17:13:59
-
Efficient Luminescence of Sr2Si5N8:Eu2+ nanophosphor and its film applications to LED and Solar cell as a downconverter
摘要： Here we present the synthesis of the efficient nanophosphor Sr2Si5N8:Eu2+ (D50 = 144 nm) by a simple milling approach, its strong Rayleigh scattering, and its film applications to white LED and silicon solar cell as a downshifting medium. The final nanophosphor product showed the quantum efficiency comparable to the bulk phosphor which is, to our knowledge, the highest record of nitride nanophosphors. Especially the nanophosphor showed the more tail emission at the shorter-wavelength side of the emission spectrum and the faster thermal quenching with the more spectral broadening along with the temperature due to Rayleigh scattering. Also the lowering in the excitation spectrum was observed due to lower absorbance. Finally, the nanophosphor-dispersed polyvinyl alcohol (PVA) film was made, and its applications to white LED and silicon solar cell as a downshifting medium demonstrated that it gave the high color rendering property in white LED in spite of still lower luminous efficiency, and it caused the increase in efficiency of silicon solar cell.
关键词： nanophosphor,white LED,milling,downconverter,solar cell,Sr2Si5N8:Eu2+
更新于2025-09-19 17:13:59