Warm White Light Research Articles

Effect of different colors and intensity of light emitting diode on the production performance, egg quality, hormonal profile and the economics of layers kept in environment control house.

This study examined the effect of LED light colors and intensities on production performance and economic feasibility of 720 Babcock® White layers. The layer birds were reared for 13weeks from 17 to 30weeks of age during the layer production cycle.Light treatments of 6 different colors, i.e., cool white (control group), red, blue, green, yellow, and warm white light with 3 different levels of light intensities (15, 20 and 25lx), were provided. Weekly growth parameters, egg production, egg quality characters and economics were evaluated. Hormonal profile (FSH, LH, GnRH, estrogen, progesterone, cortisol) and antibody titers against Newcastle Disease (ND) and Infectious Bronchitis (IB) were also evaluated. The graphical presentation was done by Origin Pro 2024. The results showed that red light increased feed intake (p < 0.05) but led to lower body weights and inefficient feed conversion ratios (FCR), whereas birds under warm white light at 25lx gained higher weight (p < 0.05), had better FCR (1.89 in the 30th week), laid more eggs (97.34% by the 30th week), with improved egg quality (p < 0.05). Mortality rates and hormonal levels also varied notably with light conditions, with warm white light showing the lowest mortality (p < 0.05) and optimal hormonal balances conducive to productivity. Birds kept under yellow and warm white light having 15lx intensity may be applied during (17-30) weeks of age to reduce the cost of production for better profitability in commercial layer farming in Pakistan.

A novel phosphor Ca3Gd0.86(AlO)3(BO3)4:0.06Dy3+, 0.08Eu3+: Warm white light, excellent thermal stability and energy transfer study

A novel phosphor Ca3Gd0.86(AlO)3(BO3)4:0.06Dy3+, 0.08Eu3+: Warm white light, excellent thermal stability and energy transfer study

Yttrium aluminum garnet fluorescent conversion films for solid-state lighting: interface reaction synthesis strategy and modulation of warm white light.

Traditional preparation of yttrium aluminum garnet (YAG) transparent ceramics involves several steps, including powder preparation, molding process and sintering at high temperature. Herein, a new and simple method was developed to prepare YAG transparent polycrystalline films directly through a novel interface reaction between sapphire and a Y2(OH)x(CO3)y(NO3)(6-x-2y)·nH2O film attached to the sapphire. The prepared YAG:5%Ce transparent polycrystalline film could be combined with a blue chip to obtain fluorescence-converted white LED, with a CCT of 6361 K and a CRI (Ra) of 73.3. Introducing 1%Pr into the YAG:5%Ce system increased the CRI (Ra) to 77.4. When these transparent polycrystalline films were combined with a blue light laser diode (LD), similar spectra were obtained under high power density (4.17 W mm-2) excitation. YAG:5%Ce films produced a white light CCT of 5471 K, LE of 165.1 lm W-1, and Ra of 62.9, while YAG:5%Ce,1%Pr films produced a CCT of 6311 K, LE of 146.5 lm W-1, and Ra increased to 69.7. This study provides a novel "powder-free" and "glue-free" synthesis strategy for preparing fluorescence-converted YAG:Ce,Pr transparent polycrystalline films, which not only overcomes the disadvantages of traditional transparent ceramic preparation methods, such as time consumption, energy consumption, and equipment dependence, but also avoids the problem of aging in traditional fluorescent conversion materials.

CaLu2Sc2Al2SiO12:Ce3+ Green Phosphors for High-Quality White LEDs.

Phosphors with broadband green emission are highly desirable for the construction of high-color-rendering warm-white light-emitting diode (LED) devices toward healthy solid-state lighting applications. However, most of the reported green phosphors are subject to an undesirable emission bandwidth and low quantum efficiency. Here, a highly efficient broadband green-emitting garnet phosphor, CaLu2Sc2Al2SiO12:Ce3+ (CLSASO:Ce3+), is successfully synthesized and investigated in detail. Upon excitation of 440 nm blue light, the as-synthesized CLSASO:3%Ce3+ phosphor features a wide bandwidth with a maximum peak situated at 534 nm and a large full width at half-maximum (fwhm) of 114 nm, which is superior to the commercial green phosphor of LuAG:Ce3+ (fwhm = 108 nm). As expected, the optimal CLSASO:3%Ce3+ sample also demonstrates satisfactory internal/external quantum efficiency of 78.3/50.1%, along with suitable CIE color coordinates of (0.3462, 0.5496). Meanwhile, temperature-dependent emission spectra measurements indicate that it retains 46% of the original integral intensity at 423 K against room temperature, together with an excellent color stability of 9.2 × 10-3. Finally, a fabricated blue-light-pumped prototype LED device with the proposed CLSASO:3%Ce3+ green component and another commercial CaAlSiN3:Eu2+ red phosphor delivers a brilliant warm-white light with a desirable color rendering index (Ra = 90.2), an acceptable color temperature of 4047 K and a superior luminous efficiency of 65.6 lm W-1. The findings illustrate that the construction of blue-light-excitable broadband green luminescence conversion material is beneficial for the preparation of a high-color-rendering warm-white LED device for high-quality general lighting applications.

Is executive attention affected by environmental lighting conditions?

Bright daylight has various positive influences, such as the long-term synchronization of circadian rhythms and an associated alertness that creates optimal conditions for attentional performance. However, the short-term effects of light on attention have not yet been sufficiently researched. Studies of these short-term effects on selective attention also showed partly contradictory effects. To investigate these short-term effects, 95 participants completed the Attention Network Test, under conditions of bright daylight or warm-white light. The focus of the present study was on executive attention, because this construct comes closest to the ANT short form of selective attention used. A significant enhancement of executive attention was observed under bright daylight conditions. This specifically means a short term effect of bright daylight on executive attention and thus selective attention in young adults.

A narrow band blue phosphor NaBa4Al2B8O18Cl3:Eu2+ for white light emitting diodes.

Exploring new photoexcited phosphors has attracted attention for improving the performance of white LEDs. Here, an NaBa4Al2B8O18Cl3:xEu2+ phosphor with high color purity (94.11%) has been synthesized. The NBAC:0.035Eu2+ phosphor exhibits excellent color stability when the temperature increases from 298 K to 473 K. Impressively, the NBAC:0.035Eu2+ blue phosphor still exhibits excellent chemical stability after being immersed in water for 25 days. In addition, Eu2+ ions preferentially occupy the Na/Ba sites of the host structure, which contributes to the superior photoluminescence performance. Furthermore, near-ultraviolet (n-UV) pumped phosphor-converted white light-emitting diodes (pc-WLEDs) have been fabricated using the NBAC:0.035Eu2+ blue phosphor, green commercial phosphor (Sr,Ba)2SiO4:Eu2+ and red commercial phosphor (Ca,Sr)AlSiN3:Eu2+. The resulting device shows uniformly distributed warm white light with a color-rendering index (Ra) of 89.2 and a low correlated color temperature (CCT) of 4153 K. A series of excellent characteristics of NBAC:0.035Eu2+, including high-performance optical characteristics, a simple synthesis process and low economic cost, support its great application potential for use in warm white LED lighting systems.

The effects of LED lights in different colors on fattening performance, litter characteristics, meat properties, and some welfare parameters in broilers

Light is important for broiler rearing which can affect economically significant performance traits. The purpose of this study was to investigate the effects of daylight (DL), warm white (WWL) and blue light (BL) on broiler fattening performance, carcass characteristics, meat quality, litter characteristics and welfare. In the study, 216 male chicks were used. Chicks were weighed and housed randomly in 3 light-controlled rooms (n=72), each containing 9 separate pens (8 chicks per pen). During the experiment body weight, weight gain, feed consumption, and feed-to-gain ratio were calculated weekly. Carcass yield and percentages of internal organs were determined. Tonic immobility duration, footpad, and breast burns of broilers, pH, and moisture of litter, cooking loss, and water-holding capacity of the breast meat were analyzed. At the end of six weeks of the experiment, the body weight (P&amp;lt;0.001), body weight gain (P&amp;lt;0.001), and total feed consumption (P&amp;lt;0.01) were lower, and feed-to-gain ratio (P&amp;lt;0.01) was higher for broilers reared under the BL. At the end of the fattening period, the tonic immobility duration, footpad &amp;amp; breast burns of broilers, and moisture &amp;amp; pH levels of the litter did not change according to the lighting groups (P&amp;gt;0.05). The differences among the groups in terms of, carcass yield, percentages of heart, liver, gizzard &amp;amp; abdominal fat, and examined meat properties were found as statistically insignificant (P&amp;gt;0.05). As a result, BL has a negative impact on the growth performance of broilers. However, carcass and carcass characteristics, litter parameters, meat quality and welfare characteristics were similar among examined light color groups.

Wavelength-Tunable Textile-Based Organic Light-Emitting Diode for Multifunctional Wearable Photomedical Applications and Display with Cool White to Warm White Light

Wavelength-Tunable Textile-Based Organic Light-Emitting Diode for Multifunctional Wearable Photomedical Applications and Display with Cool White to Warm White Light

Dual-mode emission optical temperature sensor and white light-emitting diodes using Ca2Mg0.01Y7.73Si6O26:0.24Bi3+, 0.02Eu3+ phosphors regulated by cation-controlled crystal fields

Dual-mode emission optical temperature sensor and white light-emitting diodes using Ca2Mg0.01Y7.73Si6O26:0.24Bi3+, 0.02Eu3+ phosphors regulated by cation-controlled crystal fields

Optical investigation of Dy3+/ Eu3+ co-activated K2NaAlF6 fluorophosphor for color tunable lighting system: Structural analysis and warm light generation

Optical investigation of Dy3+/ Eu3+ co-activated K2NaAlF6 fluorophosphor for color tunable lighting system: Structural analysis and warm light generation

Environmental Proteomics Elucidates Phototrophic Biofilm Responses to Ornamental Lighting on Stone-built Heritage

Recent studies are showing that some lights suitable for illuminating the urban fabric (i.e. that do not include the red, green and blue sets of primary colours) may halt biological colonisation on monuments, mainly that caused by phototrophic subaerial biofilms (SABs), which may exacerbate the biodeterioration of substrates. However, the light-triggered mechanisms that cause changes in the growth of the phototrophs remain unknown. Environmental proteomics could be used to provide information about the changes in the SAB metabolism under stress inflicted by nocturnal lighting. Here, laboratory-produced SABs, composed of Chlorophyta, Streptophyta and Cyanobacteriota, were subjected to three types of lighting used for monuments: cool white, warm white and amber + green (potentially with a biostatic effect). A control without light (i.e. darkness) was also included for comparison. The nocturnal lighting impaired the capacity of the SABs to decompose superoxide radicals and thus protect themselves from oxidative stress. Cool white and warm white light both strongly affected the proteomes of the SABs and reduced the total peptide content, with the extent of the reduction depending on the genera of the organisms involved. Analysis of the photo-damaging effect of amber + green light on the biofilm metabolism revealed a negative impact on photosystems I and II and production of photosystem antenna protein-like, as well as a triggering effect on protein metabolism (synthesis, folding and degradation). This research provides, for the first-time, a description of the proteomic changes induced by lighting on SABs colonising illuminated monuments in urban areas.

Luminescence Properties of Perovskites Doped with Lanthanides Under High-Power Excitation

Laser-induced white emission (LIWE) occurs when a material is excited with a focused infrared laser and is characterized by the emission of warm white light. Emission have a broadband character and cover visible range. It increased with a simultaneous decreasing f-f transitions. In particular the effect of excitation power density and concentration of dopants ions were investigated. The intensity of white emission was characterized by exponential dependence on excitation power density. Moreover the white emission threshold decreased with excitation photon energy. The photocurrent accompanying white emission was measured. It increased exponentially with excitation power density. The mechanism of laser induced white emission is briefly discussed in terms of multi-photon ionization and intervalence charge transfer (IVCT) mechanism. Therefore, it can be used as a new source of indoor lighting. Light parameters are similar to sunlight.The authors would like to acknowledge National Science Centre for financial support (Grant No. NCN-2020/37/B/ST5/02399).

Broadband red emission in disordered Sr2LaGaO5:Eu2+ phosphors

Broadband red emission in disordered Sr2LaGaO5:Eu2+ phosphors

Synergistic enhancement of Eu3+-doped LaAlO3 fluorescent materials by sol-gel process and aerogel structure for high power and precise transmission illumination

Synergistic enhancement of Eu3+-doped LaAlO3 fluorescent materials by sol-gel process and aerogel structure for high power and precise transmission illumination

Improved ternary composite ceramic phosphors for warm-white laser lighting

Improved ternary composite ceramic phosphors for warm-white laser lighting

Simple synthesis of AgInS2/ZnS core/shell quantum dots with wide tunable emission wavelength for white light-emitting diodes

Simple synthesis of AgInS2/ZnS core/shell quantum dots with wide tunable emission wavelength for white light-emitting diodes

Warm-White Light Emission of Lead-free CsAg2I3 Single Crystal Scintillator with a One-Dimensional Electronic Structure.

Presently, the exploration of novel inorganic lead-free perovskite scintillators has emerged as a prominent topic in the field of perovskite materials. Extensive attention has been garnered by materials such as Cs3Cu2I5 due to their notable advantage in scintillation intensity, but the response time constants in the microsecond or even millisecond range severely constrain their potential applications in scintillators. In this study, large-sized (5-6 mm) CsAg2I3 single crystals with an ultrafast warm-white light emission on a nanosecond time scale are presented. Specifically, upon X-ray excitation, the single crystal demonstrates a broad-spectrum white light emission with a color temperature as high as 5129 K, attributed to its self-trapped exciton emission. The 137Cs energy spectrum reveals that CsAg2I3 possesses an ultrafast response for γ rays with a time constant of 15 ns, which is significantly faster than that of Cs3Cu2I5. Furthermore, time-resolved photoluminescence unveils a subnanosecond component with a response time of 0.9 ns. The characteristics of ultrafast warm-white light emission exhibit the significant potential of CsAg2I3 in radiation scintillation detection and its probability of playing a pivotal role in future radiation detection technology.

High thermally stable and efficient rare-earth celsian by phase transformation of Ba2+-Exchanged SOD zeolite

High thermally stable and efficient rare-earth celsian by phase transformation of Ba2+-Exchanged SOD zeolite

Novel narrowband emitting red phosphor Sr3La2W2O12:Eu3+ with excellent thermal stability for WLEDs

AbstractThe development of red phosphors with good thermal stability, high quantum yield and high color purity is still a big challenge. In this work, a series of novel red phosphors Sr3La2W2O12:xEu3+ (0≤x≤0.18, ∆x = 0.03) were successfully prepared by high‐temperature solid‐phase method. The phosphors reveal a hexagonal phase with the space group of R‐3 m. The phosphor Sr3La2W2O12:Eu3+ produced narrowband red emission from 5D0→7F2 of Eu3+ (616 nm) under excitation at 395 nm, 465 nm, and 533 nm. Importantly, phosphor Sr3La2W2O12:0.09Eu3+ exhibits astonishing quantum efficiency (IQE = 89.60%, EQE = 41.52%), and it demonstrate robust thermal performance with the emission intensity retaining 92.73% at 558 K of that at 298 K. Finally, the prepared red phosphor Sr3La2W2O12:0.09Eu3+ and yellow phosphor YAG:Ce3+ were combined with a blue LED chip (460 nm) to form a WLED device, which presented warm white light with color coordinates of (0.3523, 0.3732), color rendering index of 83.7, and color temperature of 4826 K.

Tuning of bandgap for warm white light emissions in indium-doped cesium metal halide perovskites by solvothermal method

Tuning of bandgap for warm white light emissions in indium-doped cesium metal halide perovskites by solvothermal method