Lighting Applications Research Articles

UVC light as a strategy for disinfection of hospital air and surfaces

Objective: To evaluate a fixed UV-C light emitting device for its antimicrobial effectiveness in the disinfection of distinct surfaces and its antifungal effectiveness on air quality in the hospital environment. Methods: This quasi-experimental study was conducted in a hospital inpatient unit, in which a six-stage air Biosampler (Andersen®) was used for air analysis. In the evaluation of surfaces, three suspensions of microorganisms (Acinetobacter sp. multidrug-resistant, Escherichia coli, and KPC-producing Klebsiella pneumoniae) were used to contaminate the environment. In both evaluations, pre- (control) and post-activation of UV-C light (test) collections were made. Results: In the air evaluation, an important reduction was observed in the colony count after irradiation with UV-C light, and pathogenic or toxigenic fungi were not found in either of the two moments. Regarding the disinfection of surfaces, no bacterial growth was observed after the application of UV-C light, showing 100% bacterial inactivation under the tested conditions. Conclusion: The use of fixed UV-C light emission technology was effective and can be considered a promising intervention for hospital surface disinfection protocols.

Optical and Visual Performance of PWM Controlled InGaN and InGaAlP LEDs for Automotive Lighting Applications

Optical and Visual Performance of PWM Controlled InGaN and InGaAlP LEDs for Automotive Lighting Applications

Electrical Power Generation Using Speed Breaker Mechanism: An Innovative Approach to Energy Harvesting

Energy is essential for modern human life, yet conventional energy sources are depleting rapidly. This paper introduces an innovative method for generating electrical power using speed breakers, converting the kinetic energy from vehicles into mechanical energy, and then to electrical energy through a rack-and-pinion mechanism. The generated power can be stored and used for street lighting and other applications. This sustainable approach offers a clean, low-cost, and efficient solution for small-scale power generation, especially in urban areas with significant traffic. The study explores the system's design, methodology, advantages, and performance in different traffic conditions.

Environmentally-Friendly Europium-Based Yellow Perovskite Nanocrystals with Near-Unit Efficiency for White LED.

Recently, Mn2+-doped metal halide perovskites (MHPs) have been extensively studied as they can improve the photoluminescence quantum yield (PLQY) with minimal self-absorption. However, almost all of them with high efficiency are Pb/Cd-based toxic heavy metal perovskites, which seriously limits their commercial applications. To address the dual needs of high efficiency and environmental protection, this study proposes to incorporate Mn2+ into the environmentally friendly perovskite CsEuX3 (X = Cl/Br), and further increases PLQY to 96.9% through the codoping of Tb3+, which, to the best of our knowledge, is the highest reported value of all inorganic environmentally friendly perovskites in the visible light region. It is found that the codoping of Tb3+ can reduce the host defect density and enhance the crystal field strength around Mn2+, acting as an energy transfer bridge. Additionally, Mn2+/Tb3+-codoped CsEuX3-based white light-emitting diodes (WLEDs) with a high color rendering index (Ra = 91.2) demonstrate potential for lighting applications.

Tinjauan Analisis Manfaat dan Dampak Sinar UV-C dalam Bidang Pangan dan Pertanian

UV-C light exposure has been widely applied in food and agriculture to improve product quality, safety, and durability. UV-C light has short wavelengths that are effective in inactivating pathogenic microorganisms in food and plant products, thereby reducing the risk of contamination and extending product shelf life. In agriculture, the application of UV-C light to crops can increase crop resistance to pests and diseases, and stimulate certain physiological responses that support growth.

Design and Synthesis of Aggregation‐Caused Quenching Hydroxy‐Phenanthroimidazole Derivatives for Probing of Fe3+ Ions and as Potential Blue Light Emitters

AbstractFluorescence aggregated molecules tend to employ versatile opportunities in metal ion probe sensors and fluorescent lighting. To achieve this dual challenging task, currently synthesized three phenanthroimidazole‐naphthalene‐based compounds Pq‐tBu‐OH, Pq‐mF‐OH, and Pq‐pF‐OH are derived based on substitution at N1 position for better photophysical and electrochemical properties. Compared experimental and theoretical calculations define the highest bandgap to be 2.75 eV of Pq‐pF‐OH, and the same molecule expressed a higher (348 °C) thermal decomposition. The calculated singlet and triplet energies found in the range of 3.24–3.67 and 2.70–2.72 eV indicate well energy transfer from S1→S0 (quantum yield of 23.36 %, lifetime is 4.05 ns). Among the numerous morphologies, the solid form exhibited improved intensive deep blue emission (x=0.159, y=0.051), and its InGaN LED results demonstrated a strong deep blue emission at 418 nm. Moreover, the fluorophores were experimentally visualizing the aggregation‐caused quenching (ACQ) which enables the probing of Fe3+ ion. However, for the first time, the ACQ‐assisted concept is applied through synthesized molecules for Fe3+ ion probing via fluorescence spectra, Job's plot calculation, and 1H NMR results. In addition, the probe works excellently at a detection limit of 10 μM and it could also act as a potential competitor for lighting applications.

Static-spun mesoporous silica-coated CsPbBr3 blue fibres: synthesis and fluorescence properties

Due to their excellent properties, blue CsPbBr3 quantum dots show great promise for full-colour display and lighting applications. This study used acetonitrile, a polar solvent, to post-treat CsPbBr3 quantum dots, resulting in a blue shift to 453 nm. To enhance stability, these quantum dots were encapsulated within the pore structure of mesoporous silica. A flexible luminescent fiber material was prepared using poly (lactic acid) (PLA) as the substrate, demonstrating improved hydrophobicity and stable optical properties. The material exhibited a contact angle of 99.7° and maintained 82.2% of its fluorescence intensity after 30 days at room temperature. These findings highlight its significant potential for optical applications.

A perspective on structured light's applications

For the past few decades, structured light has been gaining popularity across various research fields. Its fascinating properties have been exploited for both previously unforeseen and established applications from new perspectives. Crucial to this is the several techniques that have been proposed for both their generation and characterization. On the one hand, the former has been boosted by the invention of computer-controlled devices, which combined with a few optical components allow flexible and complete control of the spatial and polarization degrees of freedom on light, thus enabling a plethora of proof-of-principle experiments for novel and old applications. On the other hand, characterizing light beams is important not only for gaining better insights into light's properties but also for potentially being used as metrics. In this perspective, we thus offer our take on a few key applied research fields where structured light is particularly promising, as well as some pivotal generation and characterization techniques. In addition, we share our vision of where we believe structured light's applications are moving toward.

Enhancement of NIR-II Emission of Er3+ by Doping Fe3+ in Double Perovskites: Multimode Luminescence for Versatile Optoelectronic Applications.

Erbium ions are commonly used to extend the photoelectric properties of metal halide perovskites from visible to near-infrared range. However, achieving high-efficiency multimode luminescence in a single system is difficult due to the weak absorption associated with forbidden 4f-4f transitions. In this study, a unique strategy is proposed to adjust multimode luminescence and enhance the second near-infrared region (NIR-II) emission in Cs2NaBiCl6 by incorporating Fe3+ ions. The as-prepared material demonstrates reversible thermochromism, driven by strong electron-phonon coupling effect, and exhibits tunable luminescence that can be adjusted by altering excitation energy and temperature. Notably, benefitting from the charge transfer transition of Fe3+-Cl- along with the influence of Fe3+ doping on the geometrical and electronic structures, the blue-excitable (450 nm) NIR-II emission around 1541 nm from Er3+ is realized for the first time, achieving an intensity 16.7 times higher and a maximum photoluminescence quantum yield (PLQY) of 22.5 %. This enhancement enables innovative applications such as two-dimensional information encryption by the multi-channel cooperative responses and improved NIR imaging. The study highlights the potential of Fe3+ doping in optimizing absorption and multimode luminescence in perovskites, opening avenues for advanced applications in blue-excitable NIR light emitting diodes (LEDs), thermometer, anti-counterfeiting, and NIR imaging.

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

Phosphor with efficient and broad range emission is necessary for lighting applications. I-III-VI group quantum dots (QDs) have the advantages of non-toxic composition and large adjustable spectrum range, and have potential applications in the field of lighting. However, the efficient luminescence of these QDs at shorter wavelengths still needs further study, which is crucial for the development of high color rendering index white light LED devices (WLEDs). In this work, wide visible range emitting AgInS2/ZnS QDs with broad band and high luminous efficiency were obtained by altering the Ag/In ratios and Zn2+ inter-diffusion with cation of AgInS2. Photo-luminescent (PL) wavelength range of the obtained core-shell structured AgInS2/ZnS extended from 703 nm to 524 nm with high PL quantum yield (QY) and stability. The champion device based on the optimized AgInS2/ZnS QDs exhibits warm white light (correlated color temperature = 3652 K) characteristics with high color rendering index (CRI Ra) of 92.85 while maintaining excellent color stability under different driving currents. These properties are far superior to those of WLEDs with YAG phosphor.

Self‐reduction triggered color tuning of Eu3+‐doped aluminosilicate glass for solid‐state white illumination

AbstractRare earth‐doped transparent glass, boasting high transmittance and excellent luminescent properties, holds great potential in the field of all‐inorganic solid‐state white illumination. Currently reported single‐structure solid‐state white lighting usually has the problems of low color rendering index (CRI) and high correlated color temperature (CCT) due to the lacking of red light emission. In this work, a novel single‐structure MgO–Al2O3–SiO2–Eu2O3 (MAS: Eu) glass with color tuning was prepared by the simple glass melting process. Interestingly, the prepared Eu3+‐doped aluminosilicate glass possessed a unique capability to achieve color emission under different excitation wavelengths. The reason for this was attributed to the good self‐reduction capability of the MAS glass, which effectively reduced Eu3+ to Eu2+ under an air atmosphere. Meanwhile, only by regulating the Eu3+ doping concentration, the MAS glass also achieved a tunable emission from blue to white to red light under 380 nm excitation. The acquisition of white light was realized through the multispectral emission of blue–green light emitted by Eu2+ and orange–red light emitted by Eu3+. Remarkably, the single‐structure MAS glass doped with 8 wt.% Eu3+ successfully achieved high‐quality white light and high thermal stability, exhibiting a high CRI of 86, a low CCT of 2761 K, good chromaticity parameters of (0.407 and 0.3192), and the emission intensity at 423 K remains above 86.35% that of room temperature. Meanwhile, the doped Eu3+ exceeded 12 wt.%, without any observable concentration quenching. Moreover, the MAS: Eu glass showed a high transmittance of 90 and a moderate thermal conductivity of 1.45 W/mK (epoxy resin ∼0.17 W/mK). These results would dramatically inspire the development of high‐quality solid‐state white lighting applications.

White Light Generation and Stability Analysis of High-Power Blue LDs with Remote YAG Phosphors

This paper presents a comprehensive analysis of white light generation and the associated aging dynamics using high-power blue laser diodes (LDs) combined with transmissive single crystal remote YAG phosphors. By systematically varying input currents (ranging from 0.6 A to 3 A) and phosphor thicknesses (250 μm and 500 μm), this study elucidates the optical and electrical characteristics of LD-phosphor systems under diverse operating conditions. The results highlight the system’s potential for stable and efficient white light generation, making it suitable for high-power lighting applications. Experimental setups included both single LDs and a 4 × 2 LD array. For the single LD, a peak optical output of 4.16 W was achieved at 3 A, corresponding to an initial luminous flux of approximately 700 Lm and a correlated color temperature (CCT) of 4653 K, with minimal color temperature shift observed during a 60 min aging process. The 4 × 2 LD array demonstrated consistent white light output across varying phosphor thicknesses, with maximum luminous fluxes of 1857 Lm at 1.4 A and 2622 Lm at 1.6 A for phosphor thicknesses of 250 μm and 500 μm, respectively. Importantly, the phosphor exhibited excellent thermal stability throughout the aging process, with the CCT maintained within a range of 4600 K to 5500 K. These findings underscore the reliability and applicability of LD-based white light systems in demanding high-power lighting environments, offering a promising alternative to conventional light sources for automotive, industrial, and specialized lighting applications.

Towards Photothermal Acid Catalysts Using Eco-Sustainable Sulfonated Carbon Nanoparticles—Part II: Thermal and Photothermal Catalysis of Biodiesel Synthesis

The main goal of this work is to evaluate the ability of sulfonated carbon nanoparticles (SCNs) to induce photothermal catalysis of the biodiesel synthesis reaction (transesterification of natural triglycerides (TGs) with alcohols). Carbon nanoparticles (CNs) are produced by the carbonization of cross-linked resin nanoparticles (RNs). The RNs are produced by condensation of a phenol (resorcinol or natural tannin) with formaldehyde under ammonia catalysis (Stober method). The method produces nanoparticles, which are carbonized into carbon nanoparticles (CNs). The illumination of CNs increases the temperature proportionally (linear) to the nanoparticle concentration and exposure time (with saturation). Solid acid catalysts are made by heating in concentrated sulfuric acid (SEAr sulfonation). The application of either light or a catalyst (SCNs) (at 25 °C) induced low conversions (<10%) for the esterification reaction of acetic acid with bioethanol. In contrast, the illumination of the reaction medium containing SCNs induced high conversions (>75%). In the case of biodiesel synthesis (transesterification of sunflower oil with bioethanol), conversions greater than 40% were observed only when light and the catalyst (SCNs) were applied simultaneously. Therefore, it is possible to use sulfonated carbon nanoparticles as photothermally activated catalysts for Fischer esterification and triglyceride transesterification (biodiesel synthesis).

Incorporating Sb (III) and Bi (III) ions into Cs2AgNaInCl6 perovskite toward efficient white-light emission with high color rendering index

Single phosphor with efficient and high quality white-light emission is necessary for lighting applications. In this work, we report a double perovskite, Cs2AgNaInCl6 with Bi3+ and Sb3+ incorporation, which demonstrates excellent white-light properties including tunable emission component and correlated colour temperature (CCT). Using the broad-band emission of self-trapped excitons (STEs) associated with Bi3+ and Sb3+ in the Cs2AgNaInCl6 host, the blue and orange dual-band STEs emission located at 460 and 565 nm covers the entire visible range to achieve high-quality white light emission. The relative intensity of the dual emission components can be adjusted flexibly by modulating the doping ratio of Bi3+ and Sb3+. The dual STEs emission shares the same optimal excitation wavelength at 340 nm. The optimal sample of Bi3+ (1 %) and Sb3+ (10 %) codoped Cs2Ag0.1Na0.9InCl6 exhibits high color rendering index (CRI) of up to 93, and high photo-luminescence quantum yield (PLQY) of 76 %. This codoping in double perovskite approach represents a promising method for achieving high-quality white lighting application within a single phosphor.

Multicolor luminescence and high efficient optical thermometric performance of Eu3+ and Sm3+ in self-activated Na2LuMg2V3O12 garnet

To develop efficient luminescence and optical thermometry materials for color display and non-contact temperature measurement, novel RE3+ (RE = Eu, Sm) doped self-activated Na2LuMg2V3O12 phosphors were prepared by a typical solid-state reaction method. Their crystal structure, morphology, multi-color luminescence and temperature sensing properties were elaborately investigated. Under UV light excitation, an intense and broad green-yellow emission band from VO43– group is observed in the Na2LuMg2V3O12 matrix, indicating its potential application in solid state lighting. After the incorporation of Eu3+ and Sm3+ ions, efficient energy transfer (ET) from VO43– group to Eu3+/Sm3+ ions occurs and the emission color of the samples can be readily tuned among different color ranges. Besides, based on the change of luminescence intensity and lifetimes of VO43– group in Na2LuMg2V3O12:Eu3+ and Na2LuMg2V3O12:Sm3+, the ET efficiency was analyzed and the mechanism is illustrated. Finally, large discrepancy between the thermal stability of VO43– group and Eu3+/Sm3+ ions are observed in the temperature-dependent emission spectra of Na2LuMg2V3O12:Eu3+ and Na2LuMg2V3O12:Sm3+. By taking advantage of the luminescence intensity ratio (LIR) between VO43– group and Eu3+/Sm3+ ions in Na2LuMg2V3O12:0.01Eu3+ and Na2LuMg2V3O12:0.07Sm3+, two new types of optical thermometry mediums were designed and their basic temperature sensing parameters were calculated.

Luminescent rare earth complexes of Ce3+, Eu2+and Yb2+with spiro-bis(pyrazolyl)borate ligands containing C–H···M interactions

Luminescent rare earth complexes based on interconfigurational 5d-4f transition have characteristics of adjustable emission spectra and short excited state lifetimes, showing potential applications in display, lighting and other fields. In this work, nine Ce3+, Eu2+ and Yb2+ complexes with spiro-bis(pyrazolyl)borate ligands, where pyrazolyl stands for pyrazolyl, 3-methylpyrazolyl, or 3,5-dimethylpyrazolyl, were designed and synthesized. Ce3+ complexes show emission colors of blue, with photoluminescence quantum yields (PLQYs) of 94%–100%; Eu2+ complexes show emission colors of yellow-green, with PLQYs of 60%–78%; Yb2+ complexes show emission colors of orange or red, with PLQYs of 3%–4%. In addition, the crystal structures and theoretical calculation results show C–H···M interactions between bridge-head H atoms of the spirane and central metal ions in these complexes. It is found that the introduction of spirane with large steric hindrance and the existence of C–H···M interactions can improve the stability of the complexes in air atmosphere.

Chromatic tuning of upconversion emission upon dual infrared wavelength co-excitation in Er3+ doped Ba3Lu4O9 phosphor

Emission color change of the upconversion luminescence materials is often required for applications in optical anti-counterfeiting, laser lighting, and 3D displays. In this work, we developed a new route for chromatic tuning of upconversion emission upon two wavelength co-excitation by changing excitation power density. The proposed route was used for Er3+ single-doped Ba3Lu4O9 phosphor which was derived from a traditional solid-state reaction. The crystal structure of the obtained Ba3Lu4O9:Er3+ phosphor was characterized by X-ray diffraction and Rietveld refinement modeling. Under individual excitation of 980 or 1550 nm, it was found that the luminescence intensity ratio of red to green changes slightly with respectively increasing excitation power density (working current of the laser) of 980 or 1550 nm laser. However, upon both 980 and 1550 nm co-excitation at the same time and by adjusting the excitation power density of one laser amongst the two lasers, the luminescence intensity ratio of red to green changes greatly with increasing excitation power density. The change of luminescence intensity ratio of red to green implies the upconversion emission color tuning. The mechanism for the color tuning was discovered. It was found that with changing excitation power density the ratio of red to green changed greatly when the phosphor was irradiated by 980 and 1550 together, but the ratio of red to green changed slightly when the phosphor was irradiated individually by 980 or 1550. It is proved that it is feasible to turn color by the method of two infrared wavelengths excitation.

Efficacy and Safety of Laser Therapy and Phototherapy in Cicatricial and NonCicatricial Alopecia: A Systematic Review Study.

In recent years, the application of various light and laser devices in the treatment of different types of alopecia has been established. This systematic review aims to assess the efficacy and safety of laser therapy and phototherapy in cicatricial and non-cicatricial alopecia. A comprehensive search was conducted on PubMed, Scopus, Science Direct, and Google Scholar. Articles were evaluated across four subgroups: alopecia areata, androgenic alopecia, telogen effluvium, and cicatricial alopecia. Included studies were published in English or Persian between January 2010 and September 2023, focusing on interventional, cohort, or case series research that achieved a minimum score of 75% on the EBL checklist. Exclusion criteria encompassed animal and in vitro studies, review articles, case reports, duplicated or irrelevant research, as well as studies that did not meet the designated EBL score. Editorial letters and case studies were also excluded. Initially, 965 records were collected, resulting in the inclusion of 58 studies in the final review: 26 on alopecia areata, 26 on androgenic alopecia, five on cicatricial alopecia, and one on telogen effluvium. Narrow-band ultraviolet B, 308-nm excimer laser, and psoralen ultraviolet A therapy showed varying effectiveness; specifically, the excimer laser was notably effective for patients with shorter disease duration. In androgenic alopecia, erbium-glass and thulium lasers effectively increased hair density but showed a gradual decline posttreatment. Low-level light/laser therapy also increased hair density and diameter and exhibited potential benefits when used alongside minoxidil, but did not significantly enhance outcomes in telogen effluvium treatment. Light/laser therapy can serve as an additive treatment for cicatricial alopecia, particularly lichen planopilaris, but has limited efficacy in treating telogen effluvium. Overall, light/laser therapies exhibit a significant positive effect on increasing hair density and diameter across various alopecia types.

Dy3+ ions in fluorophosphate glasses for luminescent white light applications

Abstract In this study, a series of fluorophosphate (FP) glasses, activated with Dy3+ ions and displaying concentration dependence, have been prepared and analysed for their suitability in luminescent white light applications. The melt quenching method was utilized to fabricate a set of FP glasses, doped with Dy3+ ions and possessing the composition of (60 − x) P2O5 + 10MgO + 10ZnO + 10BiF3 + 10KF + xDy2O3, where x ranges from 0.1 to 2.0 mol%. The structural properties of the samples were analysed using x-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FTIR), and Raman spectroscopy while the optical properties of the samples were studied using absorption and emission spectra. The amorphous nature of the FP glasses was confirmed through SEM analysis and XRD profiles. Moreover, the presence of elements in their composition was verified using EDX. The FTIR spectra of the FP glasses exhibited vibration bands consistent with the characteristic phosphate groups, which was further supported by Raman analysis. The absorption spectra were used to calculate oscillator strengths (f exp & f cal) and Judd–Ofelt (JO) parameters Ω λ (λ = 2, 4, 6). The values of Ω λ (λ = 2, 4, 6) followed this order: Ω6 > Ω2 > Ω4. The emission spectra displayed three prominent transitions in the UV–visible region: (4F9/2 → 6H15/2) blue, (4F9/2 → 6H13/2) yellow, and (4F9/2 → 6H11/2) red. The peak at 553 nm (4F9/2 → 6H13/2) was the most intense and dominant. Radiative characteristics were evaluated from the emission spectra through the employment of JO intensity parameters and refractive indices. The Y/B intensity ratio values were greater than 1, indicating the high covalency of Dy3+ ions. The colour coordinates (x, y) and correlated colour temperature values of CIE 1931 were situated in the cool white region. The comprehensive analysis suggests that these glasses have the potential to become highly favourable candidates as luminescent components for solid-state white light emitting instruments.

Thermal stable and bright yellow-emitting phosphor Na3+xK1-x(AlSiO4)4:Eu2+ for solid-state lighting

High-performance phosphors are essential for phosphor-converted white light-emitting diodes (pc-LEDs) utilized in general lighting applications. This paper introduces Eu2+-activated nepheline solid-solution yellow phosphors Na2.95+xK1-x(AlSiO4)4:0.05Eu2+ exhibiting excellent luminescent properties. All samples demonstrate an emission band at approximately 530 nm. However, the emission intensity gradually increases with higher Na+ content, progressing from Na2.95K(AlSiO4)4:0.05Eu2+ to Na3.95(AlSiO4)4:0.05Eu2+. Correspondingly, the external quantum efficiency (EQE) significantly rises from 41 % to 60 %. This enhancement in EQE is attribute to the improved absorption efficiency resulting from increased crystallinity. Notably, the emission intensity of representative phosphors at 150 °C remains above 90 % of room temperature values, indicating excellent thermal stability. A white pc-LED with a color-rendering index exceeding 85 is successfully developed using the phosphor with the highest EQE. These findings indicate that Na2.95+xK1-x(AlSiO4)4:0.05Eu2+ phosphors show promise as potential candidates for pc-LEDs in general lighting applications.