White Light-emitting Diode Lamp Research Articles

High‐Bandgap Perovskites for Efficient Indoor Light Harvesting

The use of metal‐halide perovskites in photovoltaic applications has become increasingly attractive due to their low‐temperature manufacturing processes and long charge‐carrier lifetimes. High‐bandgap perovskite solar cells have potential for indoor applications due to their efficient absorption of the spectrum of light‐emitting diodes (LEDs). This study investigates the performance of high‐bandgap perovskite solar cells under a wide range of lighting conditions, including a commercially available white LED lamp with a 5–40 000 lx illuminance range and a standard 1 sun reference. The performance of CH3NH3PbI3‐based perovskite solar cells to CH3NH3Pb(I0.8,Br0.2)3 solar cells with varying electron transport layers (ETL), including PCBM, PCBM:CMC, and CMC:ICBA fullerene combinations, is compared. Because the spectral response of perovskite solar cells covers the white LED spectrum very well, the major performance difference is related to the open‐circuit voltage and fill factor. The cells with the CH3NH3Pb(I0.8,Br0.2)3 absorber layer and the CMC:ICBA ETL demonstrate superior open‐circuit voltage and therefore a high efficiency above 29% at 200–500 lx, typical for indoor lighting.

A promising yellow-emitting langbeinite-type phosphor NaBaY2(PO4)3:Eu2+ for WLEDs.

The development of novel phosphors with excellent luminescence properties for white light-emitting diodes (WLEDs) is always a formidable task. Compared with the traditional laborious and aimless "trial and error" experiments, a mineral-inspired prototype strategy can provide an efficient and accurate method. Herein, for the first time, a novel yellow-emitting phosphor NaBaY2(PO4)3:Eu2+ was discovered using the mineral-inspired prototype strategy and cation substitution method. The phosphor was prepared via the high-temperature solid-state reaction method, and its crystal structure, luminescence properties and potential application for WLEDs were systematically investigated. The NaBaY2(PO4)3 phase was derived from the K2Mg2(SO4)3-type mineral structure and a photoluminescence study revealed that the phosphor can emit bright yellow light with a maximum at 545 nm upon excitation at 351 nm. A WLED lamp was fabricated by the use of a blend of commercial blue-emitting BaMgAl10O17:Eu2+, yellow-emitting NaBaY2(PO4)3:Eu2+ and red-emitting (Ca, Sr)AlSiN3:Eu2+ phosphors with a 380 nm LED chip. The CIE, CCT, Ra and efficiency of the as-fabricated LEDs were measured to be equal to (0.366, 0.365), 4327 K, 91.2 and 40.8 lm W-1, respectively. These results suggest that NaBaY2(PO4)3:Eu2+ could be a promising candidate for n-UV WLEDs.

Synthesis and photoluminescence properties of Ce3+ and Tb3+ doped Na3Gd(PO4)2 phosphors for white LEDs

Na3Gd(PO4)2 phosphors doped with rare-earth metal ions Ce3+ and Tb3+ were fabricated by the solid-state reaction method. Under the excitation of 340 nm light, the Ce3+-doped Na3Gd(PO4)2 phosphors exhibit a broad emission band ranging from 370 nm to 480 nm, which emitted blue light centered at 405 nm. When excited at 373 nm, the Tb3+-doped Na3Gd(PO4)2 phosphors presented a green light emission, including a strong peak located at 547 nm. In addition, both of the Na3Gd(PO4)2: Ce3+ and Na3Gd(PO4)2: Tb3+ phosphors showed excellent thermal stability at different temperatures, be specific in the Na3Gd(PO4)2: Ce3+ emission intensities at 150 °C could maintain about 84 % and the Na3Gd(PO4)2: Tb3+ could maintain about 92.9 % of those at room temperature. A prototype of the white light-emitting diodes lamp exhibiting bright white light was fabricated by using a 365 nm near-ultraviolet-emitting LED chip, combined with Na3Gd(PO4)2: Ce3+ blue phosphors, Na3Gd(PO4)2: Tb3+ green phosphors, and Na3Gd(PO4)2: Eu3+ red phosphors, which produced a high color rendering index of 89.4, and a relatively low correlated color temperature of 5496 K. Moreover, the CIE point was calculated to be at (0.3332, 0.3438), locating in the white light region. These results indicate that the as-prepared phosphors can be considered as potential candidates for ultraviolet/near-ultraviolet light-excited white light-emitting diodes applications.

Effects of different artificial photosynthetically active radiation (PAR) sources and intensity on the growth and nutrient uptake in Ulva prolifera and Neopyropia yezoensis

Fluorescent lamps and semiconductor light-emitting diodes (LEDs) lamps are commonly used as artificial light sources in the indoor algae cultivation system. In this study, we tested the effect of two types of fluorescent lamps (T8 and T5) and white LED lamp on the growth, photosynthesis, and nutrient uptake rates of Neopyropia yezoensis and Ulva prolifera under three photosynthetically active radiation (PAR) conditions (80, 150 and 300 μmol photon m2 s−1). White LED and T8 fluorescent light induced the highest and the lowest growth rates, respectively, in both species under each PAR. The effect of T5 fluorescent light on growth rate depends on the species and PAR. Interestingly, the T8 fluorescent light significantly increased the uptake rate of phosphorus under all PARs and nitrogen uptake rate was enhanced under 150 μmol photon m2 s−1 in U. prolifera, which was not observed in N. yezoensis. Our results suggest that white LED lamp is a more economical and efficient artificial light source than fluorescent lamps because of their highest enhancement of growth. The optimal PAR of T5 fluorescent light for growth is lower than T8 fluorescent light in the cultivation of U. prolifera. T8 fluorescent increases phosphorous uptake rate in U. prolifera.

Investigating the response of green and red spinach microgreen yield and chlorophyll content in varied light-emitting diode and plant nutrient

Light-Emitting Diode (LED) improves photosynthesis, vegetative development, seed germination, and chlorophyll content in a controlled-environment plant cultivation system. This study used LEDs as artificial grow illumination with 4 four distinct ratios, 100% blue, 100% red, 100% white, 67%:20%:13% red:blue:white, for 12 hours. Microgreens were watered twice daily with 250 ppm of plant nutrients, using a commercial AB mix and liquid organic fertilizer. Different LED ratios have varied lux and Photosynthetic Photon Flux Density (PPFD), i.e. 100 lux and 44.26 mol·m−2·s−1 PPFD for 100% blue; 600 lux and 20.32 mol·m−2·s−1 PPFD for 100% red; 1000 lux and 95.92 mol·m−2·s−1 PPFD for 100% white; 350 lux, and 37.33 mol·m−2·s−1 for 67%:20%:13% red:blue:white; with maintained 25-27°C of temperature and 70-80% of relative humidity. The 100% white LED lamp with AB Mix as plant nutrient resulted in the best growth of red and green spinach microgreens, with height, leaf area, fresh weight, chlorophyll a, chlorophyll b, and total chlorophyll content of 2.98 cm, 1.32 cm2, 0.14 gr, 19.05 mg/ L, 11.38 mg/L, 19.76 mg/L for green spinach and 3.01 cm, 0.91 cm2, 0.08 g, 19.12 mg/L, 9.93 mg/L, 18.50 mg/L for red spinach.

Enhanced biomass growth of lactobacillus acidophilus with CdS-NPs under visible light irradiation: Semi-artificial biohybrid system

The bacterial biomass growth in a semi-artificial biohybrid system composed of cadmium sulfide nanoparticles (as a light-harvesting semiconductor) and Lactobacillus acidophilus (as the non-pathogenic electron acceptor bacterium) was investigated. The photo-induced electrons generated from cadmium sulfide nanoparticles within the culture medium efficiently enhanced the biomass growth (about 1.15-fold) and indicated a significant difference (P-value = 0.003 (<0.05)) after 48 h of incubation at 37 °C under white light-emitting diode lamp (12 W) compared to the dark control (i.e. culture grown without nanoparticles and light exposure). Scanning electron microscopy indicated the well-distributed spherical nanoparticles on the smooth surface of the bacterium. Energy-dispersive X-ray spectroscopy revealed the presence of nanoparticles on the bacterium cell surface. The findings of this study revealed that integrating cadmium sulfide nanoparticles with Lactobacillus acidophilus under visible light irradiation had a positive effect on bacterium growth.

Photon flux density and wavelength influence on growth, photosynthetic pigments and volatile organic compound accumulation in Aeollanthus suaveolens (Catinga-de-mulata) under in vitro conditions

Aeollanthus suaveolens Mart. ex Spreng. (Lamiaceae) is an aromatic plant of African origin and is widely used in folk medicine due to its anticonvulsant and sedative effects. The aim of the study was to establish whether photon flux density (PFD) and wavelength, provided by light emitting diodes (LEDs), affect plantlet growth, photosynthetic pigment, and volatile organic compound (VOC) accumulation in Aeollanthus suaveolens. Nodal segments were grown under different PFDs (20, 57, 78, 102 and 139 μmol m−2 s−1) obtained with white LEDs lamps and under different LEDs light spectra as follows: white, green, yellow, blue, red, and combinations of red and blue (2.5R:1B; 1R:2.5B; 1R:1B) and cool white fluorescent lamps. The different light intensities affected the growth and production of photosynthetic pigments and volatile organic compounds. Plantlets grown under a PFD of 139 μmol m−2 s−1 showed greater dry weight accumulation and growth than those raised under other PFDs. The chlorophyll and carotenoid contents increased with a PFD of 20 μmol m−2 s−1. Light quality also affected plantlet growth. White LEDs light and fluorescent light were equally effective for growth and dry weight accumulation. Monochromatic red, blue, and yellow lights inhibited growth in Aeollanthus suaveolens. The concentrations of photosynthetic pigments from A. suaveolens plantlets were significantly affected by different wavelengths. Yellow wavelengths favored the production of photosynthetic pigments. The accumulation of VOCs was influenced by PFD and spectral quality.

Near-ultraviolet excited broadband orange-yellow emitting Sr8MgIn(PO4)7:Eu2+ phosphors for WLEDs with high color rendering index

As is well known, whitlockite β-Ca3(PO4)2-type phosphors are easily evolved to a new crystal structure by cation substitution, and have various crystallographic sites for doping activators to achieve luminescence. Herein, a novel broadband emitting Sr8MgIn(PO4)7: Eu2+ (SMIP) phosphor was prepared by high temperature solid state reaction. Its crystal structure was analyzed and refined via the Rietveld refinement method. The SMIP crystal presents a monoclinic system with space group C2/m. Their diffuse reflection and excitation spectra both show an intense absorption to the wavelength of 250–500 nm. And the photoluminescence spectrum exhibits a strong broadband emitting from 450 to 800 nm. Moreover, the luminescence decay curves reveal three kinds of Sr/Mg2+ crystallographic sites for Eu2+ occupying in SMIP host. For SMIP: xEu2+ samples, the optimized doping concentration was determined to be 0.03, and the energy transfer among the nearest-neighbor was dominating. Further, the activation energy was estimated to be 0.1145 eV. Finally, white light-emitting diodes (WLED) lamps were fabricated by coating the mixtures of SMIP: 0.03Eu2+ phosphors and BaMgAl10O17: Eu2+ phosphors on the surface of 400 nm near-ultraviolet chip. The optimized WLED lamp exhibits a correlated color temperature of 3034 K and a good color rendering index of 91.7. These results demonstrate the commercialized prospect of SMIP: Eu2+ materials as a broadband orange phosphor for application of solid state lighting.

Complementary absorbing ternary blend containing structural isomeric donor polymers for improving the performance of PC61BM-based indoor photovoltaics

In this study, two structural isomeric polymers, TTE36 and TTE25, were synthesized and their photophysical properties and photovoltaic device performance were investigated. Because of the different linking positions of carboxylate in their thienothiophene unit, these polymers can be classified as two isomers and exhibit significantly different properties. A mixture of these two polymers was effectively applied as the donor for a highly reliable active layer in organic indoor photovoltaics (IPVs) because of its good miscibility, and especially, of its broad complementary absorption which overlapped the emission spectrum of the white light-emitting diode lamp. The ternary IPV system, achieved by mixing the wide-bandgap TTE25 polymer with the medium-bandgap TTE36 polymer, followed by blending with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM), exhibited significantly enhanced open circuit voltage and short circuit current density, thus improving the power conversion efficiency (PCE) of the IPV system. Compared to the TTE36:PC61BM-binary-blend-based IPV system, the TTE36:TTE25:PC61BM (0.8:0.2:1.0 wt ratio)-ternary-blend-based IPV system exhibited an increase in PCE from 6.81% to 11.15% under 1000 lux white LED light illumination. These results indicate that the addition of TTE25 to the TTE36:PC61BM binary blend improves the morphology and light-harvesting properties of the active layer.

Effects of Nutrient Solution Management and Environment on Tomato in Small-scale Hydroponics

Interest in hydroponic home gardening has increased in recent years. However, research is lacking on minimum inputs required to consistently produce fresh produce using small-scale hydroponic systems for noncommercial purposes. Our objectives were to 1) evaluate the effect of biweekly nutrient solution replacements (W) vs. biweekly fertilizer addition without a nutrient solution replacement (W/O) on final growth, yield, and nutrient uptake of hydroponic tomato (Solanum lycopersicum) plants grown in a greenhouse, and 2) characterize growth over time in a greenhouse or an indoor environment using W. For each environment, ‘Bush Goliath’ tomato plants were grown for 12 weeks in 6.5-gal hydroponic systems. The experiment was replicated twice over time. In the greenhouse, plants were exposed to the following day/night temperature, relative humidity (RH), and daily light integral (DLI) in 2018 (mean ± SD): 31 ± 6/22 ± 2 °C, 67% ± 8%, and 32.4 ± 7 mol·m‒2·d‒1; and in 2019: 28 ± 6/22 ± 3 °C, 68% ± 5%, and 27.7 ± 6 mol·m‒2·d‒1. For both experimental runs indoors, the day/night temperature, RH, and DLI were 21 ± 2 °C, 60% ± 4%, and 20 ± 2 mol·m‒2·d‒1 provided by broadband white light-emitting diode lamps. The W/O treatment resulted in a higher-than-desired electrical conductivity (EC) and total nutrient concentration by the end of the experiment. In addition, compared with the W treatment, W/O resulted in less leaf area, more shoot growth, less water uptake, and similar fruit number—but increased blossom-end-rot incidence, delayed fruit ripening, and lower fruit fresh weight. Nonetheless, the final concentration of all nutrients was almost completely depleted at week 12 under W, suggesting that the applied fertilizer concentration could be increased as fruiting occurs. Surprisingly, shoot biomass, leaf area, and leaf number followed a linear trend over time in both environments. Nonetheless, given the higher DLI and temperature, greenhouse-grown plants produced 4 to 5 kg more of fruit than those grown indoors, but fruit from plants grown indoors were unaffected by blossom-end-rot. Our findings indicate that recommendations for nutrient solution management strategies should consider specific crop needs, growing environments, and production goals by home gardeners.

Red persistent luminescence excited by visible light in CaS:Eu2+,Tm3+

Excitation wavelength dependence of red persistent luminescence in phosphor is reported. Persistent luminescence appears under visible light excitation in the wavelength region of 400–600 nm. Photon energy from white light-emitting diode lamps is possibly stored in this material. This sulfide phosphor is synthesized using iodine vapor. Under iodine vapor, Eu2+ and Tm3+ are found to be efficiently included in CaS. The concentration dependence of Eu2+ is studied, and the optimum concentration is 0.05%. Trap depth of 0.27–0.33 eV contributing to persistent luminescence is evaluated by using thermoluminescence.

Sm3+-activated Y2Mo4O15 red-emitting microparticles with admirable luminescent performance for indoor illumination

Utilizing a facile sol-gel reaction route, we dealt with the fabrication and luminescent properties of Sm3+-activated Y2Mo4O15 red-emitting microparticles. At the excitation of 405 nm, the resultant microparticles showed visible red emission with color purity of 76.7%. According to the detected decay time, the theoretical internal quantum efficiencies of the compounds were analyzed. In addition, temperature-dependent emission spectra were performed to verify the thermal resistance performances of the microparticles. As proof of the suitability of the prepared compounds for solid-state illumination, a white light-emitting diode (WLED) device was packaged using the obtained microparticles, BaMgAl10O17:Eu2+ blue phosphors, (Ba,Sr)2SiO4:Eu2+ green phosphors and near-ultraviolet (NUV) chip. The designed WLED lamp enabled emit bright white light with a good chromaticity coordinate of (0.302, 0.394), satisfied color rendering index (78.3) as well as proper correlated color temperature (6552 K).

&lt;strong&gt;Behavioral response of adult caddisflies (Trichoptera) to blue and green light-emitting diode lamps&lt;/strong&gt;

To clarify the effect of the visible spectrum, we collected Trichoptera adults using blue, green, and white light-emitting diode (LED) lamps and black light (BL) lamps. Except for white LED lamps, all lamps emitted broad-band wavelengths in the ultraviolet spectrum. A total of 212 adult Trichoptera were trapped. The most individuals were attracted by BL (96), followed blue (74), green (32), and white (10). Hydroptilidae spp. was the most abundant taxa among the lamps (183 individuals, 86.3%), followed by Cheumatopsyche brevilineata (23 individuals, 10.8%). Only Hydroptilidae spp. was common to all lamps. The Shannon–Wiener diversity index (H’) was highest at 0.96 for BL, followed by green (0.53), and blue (0.28). Trichoptera were attracted to both UV light and visible light. These results suggest that BL is the most useful for faunistic investigations of Trichoptera.

Influence of light sources on body characteristics of female Japanese quail (Coturnix coturnix japonica) in different reproductive ages

The aim of the study was to evaluate the influence of different light sources on organ characteristics, bone development, chemical body composition and hepatic function of female Japanese quail (Coturnix coturnix japonica) in different reproductive ages. In total, 210 female 1-day-old birds were housed in a brick shed, which was divided into six rooms during 12 weeks. Each room was equipped with a different type of light bulb (incandescent; compact fluorescent; and white, blue, red and green light-emitting diodes (LEDs)) and contained seven cages with five birds in each. The light intensity was 15 lx and the photoperiod was 23 h light and 1 h dark (23L:1D) during the first week, 10 L:14D from the second to the fifth week, and 17L:7D until the end of the experiment. The experimental design was completely randomised, with six treatments and seven replicates of each bird. The morphophysiological conditions of the birds were evaluated at the beginning (8 weeks) and during peak production (12 weeks). At 8 weeks, a higher intestine weight and length and liver weight were observed in birds maintained in white LED (P &amp;lt; 0.05). Lower breast weight (P &amp;lt; 0.01) was also observed with this type of lamp. White and red LEDs decreased (P &amp;lt; 0.05) the percentage of ash in the tibia, but this reduction did not affect (P &amp;gt; 0.05) bone resistance. At 12 weeks, higher bone resistance was obtained (P &amp;lt; 0.01) with white LED and higher eye diameter was observed (P &amp;lt; 0.05) with incandescent and white LED lamps. There was no influence (P &amp;gt; 0.05) of light sources on the circulating levels of aspartate aminotransferase and alanine aminotransferase. Fluorescent bulbs resulted in the highest (P &amp;lt; 0.05) level of γ-glutamyltransferase, while blue LED resulted in the lowest level. There was no influence (P &amp;gt; 0.05) of light sources on chemical body composition in any of the evaluated ages. It was concluded that the photostimulation of Japanese quail with white LED is more efficient to stimulate their organ development, especially the intestine, until 8 weeks of life, resulting in birds with better bone development during peak production.

A high-efficiency, broadband-excited cyan-emitting Ba3Lu2B6O15:Ce3+,Tb3+ phosphor for near-UV-pumped white light-emitting diodes

In this present work, we reported on a novel cyan-emitting phosphor Ba3Lu2B6O15:Ce3+,Tb3+ prepared by a conventional solid-state method and evaluated its potential as a candidate for application in white light-emitting diodes (WLEDs). X-ray diffraction (XRD), photoluminescence (PL) and photoluminescence excitation (PLE) spectra, CIE color coordinates, internal quantum efficiency (IQE), and temperature-dependent PL spectra were used to characterize the Ba3Lu2B6O15:Ce3+,Tb3+ phosphor. We found that this phosphor showed strong and broad absorption in 300–425 nm wavelength region, and under excitation at 373 nm it exhibited intense cyan emission due to the combination of blue emission of Ce3+ ions peaking at 446 nm and green emission of Tb3+ ions peaking at 542 nm. The energy transfer process from Ce3+ to Tb3+ ions in the Ba3Lu2B6O15:Ce3+,Tb3+ phosphor was studied. The optimized cyan-emitting Ba3Lu2B6O15:0.03Ce3+,0.2 Tb3+ sample showed CIE color coordinates of (0.204, 0.239) and its IQE was measured to be about 51%. The performance of this phosphor was further tested by investigating its thermal stability, and the obtained results demonstrated that this phosphor possessed good luminescence thermal stability and color thermal stability. Finally, we fabricated a WLED lamp by coating the Ba3Lu2B6O15:0.03Ce3+,0.2 Tb3+ cyan-emitting phosphor with a red-emitting CaAlSiN3:Eu2+ phosphor on a 365 nm-emitting LED chip, and when driven by a 180 mA forward bias current such WLED device produced intense white light with a color rendering index of 88, a correlated color temperature of 4213 K, and CIE color coordinates of (0.375, 0.388).

Self-template construction of honeycomb-like mesoporous YPO4:Ln3+ (Ln = Eu, Tb) phosphors with tuneable luminescent properties

Rare earth (RE)-based phosphors with mesoporous structure that can improve the absorption and utilization of light have attracted much attention recently. Herein, we develop a novel and facile self-template strategy to synthesize honeycomb-like mesoporous YPO4:Ln3+ (Ln = Eu, Tb) phosphors using Y4O(OH)9NO3: Ln3+ as the precursor through a simple H3PO4 etching process. The maximum specific surface area of the mesoporous YPO4:Ln3+ phosphors can reach 406 m2 g−1. The influence of mesoporous structure, crystallinity, and the concentration of rare earth ions on the photoluminescence performance of mesoporous YPO4:Ln3+ phosphors was investigated. The results of fluorescence measurements indicate the mesoporous YPO4:Ln3+ phosphors exhibit better photoluminescence performance after calcination at 900 °C due to the large surface area and high crystallinity. The optimum doped concentrations of Eu3+ ions and Tb3+ ions are 0.12 and 0.08, respectively, and the concentration quenching occurs among nearest-neighbor ions. This work provide a new sight on preparation of phosphors for white light-emitting diodes lamps.

A Cerium Doped Scandate Broad Orange-Red Emission Phosphor and its Energy Transfer-Dependent Concentration and Thermal Quenching Character.

A series of BaSr2Sc4O9 and Ce3+-doped BaSr2Sc4O9 phosphors were synthesized via the high temperature solid state reaction. Crystal structure information on BaSr2Sc4O9 is first refined using the Rietveld method based on the XRD data, and it is assigned to the trigonal system with the R3 space-group. The photoluminescence properties were investigated in detail, including the emission and excitation spectra, site occupation, decay lifetime, thermal quenching, and quantum efficiency. There are three Ba2+/Sr2+ sites and four Sc3+ sites in this structure. The Ce3+ ions in the 6-fold coordinated Sr2+/Ba2+ sites show a near-ultraviolet-blue emission with a peak at around 407 nm under ultraviolet excitation. The Ce3+ ions in Sc3+ sites exhibit a bright broad orange-red emission with the peak at around 615 nm under near-ultraviolet and blue excitation. The energy transfer process between the different sites is demonstrated based on the spectral analysis, theoretical calculation, and decay lifetime variation. Under excitation of 345 nm, the energy transfer phenomenon and distribution of activator ions lead to the invalidation of part of the Ce3+ ions, and then it causes a higher concentration quenching point. The participation of the energy transfer in the thermal quenching phenomenon causes the abnormal intensity variation, which is ascribed to the energy compensation by the increasing energy transfer efficiency at high temperature. The internal quantum efficiency is 45% under the 420 nm excitation wavelength. An excellent white light emitting diode lamp is obtained by fabricating BaSr2Sc4O9:Ce3+ with BAM:Eu2+, β-sialon:Eu2+, and a 395 nm GaN chip; its CIE coordinate ( x, y), CCT, and Ra are (0.3708, 3463), 4023 K, and 84. These results reveal the correlation between energy transfer and luminescent property and provide a practical foundation to comprehend and adjust the photoluminescence performance.

Efficient Energy Transfer within Dyes Encapsulated Metal–Organic Frameworks to Achieve High Performance White Light‐Emitting Diodes

AbstractThe development of phosphor‐converted white light‐emitting diodes (WLEDs) with high quantum yield, high color‐rendering index (CRI), and moderate correlated color temperature is highly desirable and remains a challenging task. Herein, a new yellow phosphor is designed and synthesized via the simultaneous encapsulation of three highly luminescent dyes, Cou‐6, R6G, and R101 into microporous metal–organic frameworks (MOFs) ZJU‐28. Due to the matched spectral overlap and efficient energy transfer processes among these dyes within MOFs, the single‐phase phosphor ZJU‐28⊃Cou‐6/R6G/R101 (0.016 wt% Cou‐6, 0.010 wt% R6G, and 0.014 wt% R101) emits bright and warm white light with high quantum yield of 82.9%, under the excitation of 460 nm blue light. In addition, by integrating the MOF phosphor on commercially available 460 nm blue LED chips, a high performance WLED lamp with a luminous efficiency value of 126 lm W−1, moderate correlated color temperature of 4446 K, and high CRI of 88 is obtained, opening a new perspective for the development of white‐light‐emitting diodes.

Image Permanence of photographic prints under LED lighting

LED (Light Emitting Diode) lighting has been widely used as a major light source to illuminate photographic prints. But it is not clear how aggressive LED lighting affects to image stability of prints. The light stability tests were carried out using some commercially available white LED lamps and fading behavior was compared to the standardized xenon light testing which simulates indirect sunlight indoor. It was clarified that fading under LED lighting is less than xenon lighting but it correlates well to the xenon testing in the order of prints in light stability.

The Enhanced Red Emission and Improved Thermal Stability of CaAlSiN₃:Eu2+ Phosphors by Using Nano-EuB₆ as Raw Material.

Synthesizing phosphors with high performance is still a necessary work for phosphor-converted white light-emitting diodes (W-LEDs). In this paper, three series of CaAlSiN3:Eu2+ (denoted as CASN:Eu2+) phosphors using Eu2O3, EuN and EuB6 as raw materials respectively are fabricated by under the alloy precursor normal pressure nitridation synthesis condition. We demonstrate that CASN:Eu2+ using nano-EuB6 as raw material shows higher emission intensity than others, which is ascribed to the increment of Eu2+ ionic content entering into the crystal lattice. An improved thermal stability can also be obtained by using nano-EuB6 due to the structurally stable status, which is assigned to the partial substitution of Eu–O (Eu–N) bonds by more covalent Eu–B ones that leads to a higher structural rigidity. In addition, the W-LEDs lamp was fabricated to explore its possible application in W-LEDs based on blue LEDs. Our results indicate that using EuB6 as raw materials can provide an effective way of enhancing the red emission and improving the thermal stability of the CASN:Eu2+ red phosphor.