Lighting Applications Research Articles

Colorful Narrow‐Band Organic Polariton Light‐emitting Diodes Based on a Single Emitter

AbstractOrganic light‐emitting diodes hold promise for producing multicolor, narrowband emissions, and high‐definition displays. However, achieving a wide color gamut and strict color purity with high fidelity in line with BT.2020 standards is challenging. Here, a method is developed that incorporates organic films into a microcavity, leading to efficient organic polariton electroluminescence. The polariton OLEDs offer several advantages, such as a low turn‐on voltage, the ability to emit in six distinct narrowband colors covering blue to red, and robustness at current densities up to 118 A cm−2. By controlling photonic components, a wide color gamut and high color purity can be achieved. Remarkably, the method enables the red‐emitting devices to overcome the challenges posed by the exciton dark state, where the oscillator strength of the exciton is negligible. This innovation has the potential to promote the realization of electrically driven organic solid‐state lasers integrated into single‐component systems for cutting‐edge display and lighting applications.

Fabrication of broadband-emissive micro/nanostructures using two-photon lithography.

The development of broadband emissive micro/nanoscale structures has enabled unprecedented opportunities to innovate multifunctional devices with applications in lighting, display, sensing, biomedical, photovoltaics, and optical communication. Realization of these micro/nanostructures require multi-step processing, and depends on sophisticated, complex, time-consuming, expensive, and conventional nanofabrication techniques such as mask-based photolithography, electron beam lithography, reactive ion etching. Precise control over z-axis features with a subwavelength resolution for the fabrication of 3D features is a challenge using these methods. Thus, the traditional methods often fall short of meeting these requirements simultaneously. Fabrication of emissive structures demand techniques that offer material compatibility, high resolution, and structural complexity. Here, we report single-step fabrication of 1D, 2D, and 3D broadband emissive micro/nanostructures using two-photon lithography (TPL). The broadband emissive resin used for fabricating these structures is made by combining synthesized functionalized carbon quantum dots (CQDs) with a commercially available acrylate-based resin. The resulting structures demonstrate excellent broadband emissive properties in the visible range under UV-Vis excitation.We have observed consistent emission across the fabricated structures along with good thermal and optical stability. Furthermore, we can tune the emission properties of the micro/nanostructures by modifying the functionalization/doping of the quantum dots. These micro/nanostructures have the potential to be used as fundamental components in photonics, particularly in the fields of biophotonics, sensing, and optoelectronics, and could drive new innovations in these areas.

ANALISA TITIK LAMPU RUANG TAMU DAN RUANG KELUARGA RUMAH TYPE 90 M2

This research aims to analyze the lighting needs for the living room and family room in a 90 m² house. Using a quantitative descriptive method, the findings showed that optimal lighting in the living room requires two 11-watt light points for a 7.05 m² area, while the family room needs four light points for an 11.4 m² area. Efficient lighting can be achieved through the use of LED lights, ensuring even light distribution based on the visual needs of the space. Recommendations should be validated to ensure compliance with SNI standards and visual comfort. The research provides useful guidance for the effective application of artificial lighting in 90 m² houses

High cyan-emissive CsPbCl1.5Br1.5 quantum dots borosilicate glass modified by SrO

Currently, it has been found that white light emitting diode (WLED) lack cyan light, which not only hinders high-color-quality lighting applications but also results in an excess of blue light in WLED. In this work, cyan-emissive CsPbCl1.5Br1.5 quantum dots (QDs) were synthesized in a borosilicate glass matrix using a high-temperature melting method. The findings suggest that the increasing SrO leads to a looser glass network, which in turn intensifies phase separation, promotes the crystallization of QDs and enhances the intensity of cyan PL. Significantly, after a heating-cooling cycle, the cyan-emissive glass sample still retained 97% of its initial PL, suggesting that the synthesized sample exhibited good thermal stability. Finally, the prepared cyan-emissive QDs glass was incorporated into a WLED, effectively fills the lack of cyan light in 470-500 nm, showed a color rendering index (CRI) of 78 at a correlated color temperature (CCT) of 8300 K. This study provides an effective and convenient approach to enhancing the cyan luminescence performance of QDs, highlighting the significant application potential of cyan-emissive QDs glass in optoelectronic devices.

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.

Investigation into the feasibility of a lightguide based prevention of catheterassociated urinary tract infections (CAUTI)

Abstract Catheter-associated urinary tract infections are among the most common hospital-acquired infections and all previous measures to reduce their incidence have been less successful. Therefore, the present study investigates an approach based on the antimicrobial effect of visible light. The radiation of a violet or blue LED is guided via optical fiber with a diffuser tip into a catheter surrounded by an E. coli suspension (phosphate buffered saline or urine) in a simple urinary tract model. The irradiation led to bacterial reductions of up to several orders of magnitude that depended on various parameters. Violet light had a stronger antimicrobial effect than blue light, even in the experiments with urine, which absorbs violet light more strongly than blue light. An increase in irradiation intensity led to a greater reduction in bacteria. Human cells are not expected to be damaged by this irradiation. Therefore, the application of violet light to prevent catheter-associated urinary tract infections seems particularly promising but should be tested on even more realistic models in the future, which should not only include planktonic cells but also biofilms.

Single Phase Induction Motor Electrical Performances

Abstract A single-phase induction motor (SPIM) is one of the most widely used types of electric motors for applications that require small to medium power even his features don’t look very efficient energy parameters point of view. This motor runs on single-phase AC power, a real advantage for residential and light industrial applications and coupled with a DC permanent machine can emphasize its behavior in some specific situations. Starting and running performance of single-phase induction motor depend on running torque requirements of the load. Some statements about power factor and efficiency will be done, also.

Effects of 660 nm red light and 850 nm near infrared light on human blood lymphocytes

Abstract The applications of light emitting diodes (LED) as a red light therapy (RLT) source for the management of various conditions such as wound treatment, control of inflammation and pain have been growing continually. Despite its extensive medical application, the effects of RLT on living cells are still highly contested. This study is conducted to test the effects of RLT using combined LED source with 660 nm (red) and 850 nm (near infrared) light on cultured human lymphocytes in vitro. To analyze the effect of RLT on human peripheral blood lymphocyte’s proliferation, the mitotic index (cytostatic effect) is monitored under different irradiation exposure time parameters and conditions. This value indicates how a particular treatment affected cell division, either proliferatively, inhibitory, or had no effect at all. The interpretation of the results of the mitotic index is done in relation to the mitotic index of the untreated (unirradiated) control cells. Our data shows higher lymphocyte proliferation for all of the irradiated samples, and is particularly enhanced by multiple exposures to red light. The effectiveness of RLT on cell activity is of importance in determination of suitable treatment for diseases related to the immune system. To better understand the molecular and metabolic mechanisms involved in red LED-induced photobiomodulation, the study will be extended to investigate the RLT effect on cell protein synthesis.

Warm white light phosphors Sc2W3O12: Dy3+, Eu3+ with ultrahigh thermal stability and tunable luminescence

Phosphors for lighting applications often face challenges such as limited thermal stability, restricted tunability of emission colors, and moderate quantum efficiency. In this study, a series of Sc2W3O12: xDy3+, yEu3+ phosphors were synthesized via a high-temperature solid-state method to address these issues. Under 350 nm excitation, Sc2W3O12: xDy3+ phosphor exhibits blue (485 nm) and yellow emission peaks (577 nm), and the optimal doping concentration of Dy3+ is 3 mol%. In Sc2W3O12: 0.03Dy3+, yEu3+ phosphor, energy transfer is revealed through spectral overlap and fluorescence decay curve analysis of Dy3+ and Eu3+. The energy transfer efficiency is as high as 75 %, and the reason is explained through a combination of energy transfer mechanism and J-O theoretical calculation. By adjusting the range of y in Sc2W3O12: 0.03Dy3+, yEu3+, the correlated color temperature can be adjusted within the range of 4450 K to 3945 K, thereby achieving tunable luminescence from neutral white light to warm white light. The thermal stability of the synthesized warm white phosphor Sc2W3O12: 0.03Dy3+, 0.05Eu3+ is 90.38 % (423 K). The fluorescence intensity ratio of Eu3+ and Dy3+ at 303 K − 483 K was calculated, and its temperature sensing performance was analyzed. At 303 K, the thermal sensing factors are Samax = 0.97 % K−1 and Srmax = 0.0962 % K−1, and the actual quantum efficiency is IQE = 50.67 %. Finally, a WLED device was prepared using Sc2W3O12: 0.03Dy3+, 0.05Eu3+ phosphors. The device emits warm white light with a correlated color temperature of 3686 K. In summary, the prepared Sc2W3O12: Dy3+, Eu3+ phosphor successfully solved the challenges of limited thermal stability, tunable luminescence color and moderate quantum efficiency, and it has potential value in white light-emitting diodes (WLEDs) and optical thermometers.

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

Optical and Band Gap Study of Violet-Blue Broadband Emitting Dy3+ Codoped Y2SiO5:Ce3+ Phosphor for nUV White Light-Emitting Diodes.

Y2SiO5:Ce3+, Y2SiO5:Dy3+, and Y2SiO5:Ce3+ and Dy3+ phosphors were successfully synthesized using the oxalate wet chemical method. Phase purity, emission and excitation spectra, FTIR, and the chromaticity coordinate were adopted to represent the performance of the samples. The photoluminescence (PL) spectrum Y2SiO5:Ce3+ and Dy3+ phosphor shows a broadband in violet-blue region with a bandwidth of nearly 75 nm due to combine effect of Ce3+-Dy3+ ions with another emission peaks of Dy3+ ions peaking at 574 nm. It has been discussed how the Ce3+-Dy3+ ion pair enhances the PL intensity of violet-blue light through efficient energy transfer (ET). The chromaticity coordinate of Y2SiO5:Ce3+ (1 mol%), Dy3+ (0.3 mol%) phosphors is 𝑥 = 0.167 and 𝑦 = 0.034. The CCT value is used to find color temperatures. The energy band gap and refractive index of Y2SiO5:Dy3+ are determined using the bonding parameter and Tauc's plot. Prepared phosphors might be an excellent choice for lighting applications based on all of the findings.

Red-emitting phosphors NaLiXF6:Mn4+ (X = Ti, Si) for white LEDs with high color rendering index and low correlated color temperature

White light-emitting diodes (WLEDs) are widely used in various lighting applications due to their high brightness and energy efficiency. However, commercial WLEDs, which typically combine YAG:Ce3+ phosphors with blue light-emitting diode chips, often lack red components, resulting in a high correlated color temperature (CCT) and a low color rendering index (CRI). To address this issue, two novel Mn4+-doped red-emitting phosphors, NaLiTiF6 and NaLiSiF6, were synthesized using an ion exchange method. Both phosphors exhibit strong red light with a pronounced zero-phonon line (ZPL) emission under blue light excitation. Optimal photoluminescence emission intensities were observed at Mn4+ concentrations of 6% for NaLiTiF6 and 9% for NaLiSiF6. When the temperature increased from 303 K to 413 K, both phosphors demonstrated outstanding brightness and chromatic stability. Integrated into phosphor-converted light-emitting diodes (pc-LEDs), the device incorporating NaLiTiF6:6%Mn4+ achieved a CRI of 95.1 and a CCT of 3172 K, while the device with NaLiSiF6:9%Mn4+ showed a CRI of 87.9 and a CCT of 3784 K. In addition, the luminous efficacy, CRI, and CCT of both prototype pc-LEDs maintained minimal variation with increasing driving current. These results indicate the stability and suitability of the synthesized phosphors for enhancing the performance of warm WLEDs applications.

Outlining the impact of electro-osmotic force and mixed convection flow of EMHD nanofluid flow on the stretched cylinder: a computational layout

Abstract This research has focused on studying the electro-magneto-hydrodynamic (EMHD) nanofluid flow over a stretched cylinder in the presence of electro-osmotic force and mixed convection. This inquiry shows a novel approach through the use of thermophoresis and Brownian motion and nanofluid is comprised of water and copper nanoparticles. Similarity transformations simplified the mathematical model and produced nonlinear ordinary differential equations with suitable boundary conditions, which the MAPLE-21 software numerically solved using the RK-4 shooting criteria. Tables and graphs have been used to illustrate the impact of the key flow factors on Electric potential profiles, velocity profiles, temperature outlines, and concentration distribution. Following the physical deliveries, we have calculated the Sherwood number, Nusselt number, and skin friction. The electro-osmotic parameter diminishes the electric potential profiles and a dual effect occurs for the curvature parameter. The Nusselt number declined by 5.91 % for the electro-osmotic parameter but the Sherwood number enhanced by 30.7 % at a rate. The practical applications of this model shed light on thermal management in electronics and nuclear reactors, plasma physics, various chemical processes, filtration, separation, and fuel cells, as well as the manipulation of biological fluids in lubrication or medical devices.

Rapid osmocontractile response of motor cells of Mimosa pudica pulvini induced by short light signals.

The Mimosa pudica leaf has motor organs allowing movements driven by cell osmotic changes in the parenchyma cells in response to various stimuli. Short white light pulses induce rapid and large seismonastic-like movements (denoted "photostimulation") of the primary pulvini in various leaves within 120 s after the onset of light. An early event recorded is a wavelength-related modification of the plasma membrane difference: potential depolarization under white, blue, green, and red wavelengths, and hyperpolarization under far red wavelengths (and also in darkness). The photoreactivity of the pulvini is controlled by a circadian rhythm and modulated by the applied diurnal photoperiod cycle (photophase ranging from 6 to 18 h). The reactivity varied among plants and even between leaves on the same plant. The level of reactivity is related to the photon fluence rate in the range from 10 to 140 μmol m-2 s-1 under white light and to the experimental temperature in the range 15°C-35°C. An "accommodation" to light supply is evidenced by a modulation of the reactivity in relation to the schedule of light application under low fluence rates and the introduction of short darkness intervals during the first 30-s light pulse. The blue light-induced photostimulation is under phytochrome control.

Synthesis of thermally stable orange light-emitting phosphors: characterization and investigations of Sm3+-doped CsCaF3 phosphors for solid-state-lighting applications

In this study, we synthesized and characterized pure CsCaF3 and CsCaF3 doped with samarium (Sm3+) ions using a solid-state method. X-ray diffraction analysis was employed to examine the crystal structure, while field emission scanning electron microscopy analyzed the surface morphology of the doped sample. A color coordinate graph was used to calculate the color, with the Commission Internationale de l'Eclairage (CIE) fitting the color of both pure and doped samples. Upon excitation at 405 nm (6H5/2→6F7/2 transition), the doped CsCaF3 emitted an orange light. The CsCaF3:Sm3+ sample (0.8 mol%) displayed 86% color purity and a color temperature of 2191 K, making it suitable for lighting applications. The thermoluminescence (TL) curve of the beta-irradiated CsCaF3:Sm3+ (0.8 mol%) sample showed peaks at 174 °C and 297 °C. Preheating techniques eliminated the low-temperature peak, and the peak temperature of maximal TL intensity (Tm) was 297 °C. The activation energy (Ea) and frequency factor (s) were determined using the peak shape method and varying heating rates. The dosage response of CsCaF3:Sm3+ (0.8 mol%) was examined for potential dosimetry applications.

Exploring the influence of emissive centers in mono and dinuclear europium(III) complexes for advance lighting applications: Synthesis, characterization and computational modelling

The combination of 4,4,4-trifluoro-1-phenyl-1,3-butanedione (TFPB) and pyrazine (pyz) with Eu3+ ions results in the formation of two distinct types of complexes, characterized by general formulae [Eu(TFPB)3(L)2] (here, L is either H2O or pyrazine) and [(Eu(TFPB)3)2pyz]. The impact of surrounding environment on the photophysical properties of synthesized complexes was thoroughly examined. Photoluminescence (PL) analysis revealed the dominance of electric dipole (ED) transition (5D0→7F2) in these complexes. Theoretical calculations via Judd-Ofelt analysis were also performed. These complexes exhibit visible luminescence in both solid and solvated forms. Notably, the luminescence intensity of prepared dinuclear complex is found to be manifolds greater than its mononuclear analogues, affirming the contribution of both metal centers towards emission intensity. Furthermore, the absence of ligand centered emission in prepared complexes suggests the effective energy transfer from coordinated moieties to metal center. CIE color coordinates of prepared Eu(III) complexes, in both solid and solution media, exhibited intense red emission. DFT calculations were conducted to elucidate the distribution of electronic density in synthesized complexes. Additionally, a comprehensive analysis of these complexes, including IR, UV, NMR, thermogravimetry and cyclic voltammetry was conducted.

Approaches for white organic light-emitting diode via solution-processed blue and yellow TADF emitters: Charge balance and host-guest interactions in a single emission layer

[Display omitted] Although OLEDs are widely employed nowadays for display technology devices, their application for room-lighting illumination remains a challenge due to the cost-effectiveness issues, mainly related to device fabrication. In this sense, the present study investigates the optimization of blue-emitting TADF (DMOC-DPS) and yellow-emitting TADF (TXO-TPA) compounds in solution-processed OLEDs to achieve efficient white light emission in a two-organic layer device. Four different host materials were studied, aiming to balance the charge mobility of holes and electrons. The host materials used include (in %wt.) a 1:1 mixture of mCP and DPEPO (HOST1), a 3:2 mixture of PVK and DPEPO (HOST2), a 3:2 mixture of PVK and mCP (HOST3), and a 3:2 mixture of PVK and butyl-PBD (HOST4). The experimental results obtained from the solution-processed OLEDs indicate that DMOC-DPS is predominantly a hole transport material, and hosts with predominantly n-type character, such as HOST1 and HOST4, resulting in the most efficient white-OLEDs by the most balanced charge mobility. With structure optimization, WOLEDs achieved 6.43 % EQE with a brightness of 2621 cd/m2 (not integrated) and 6.06 % EQE with a brightness of 1986 cd/m2 for HOST4 and HOST1, respectively. The emission characteristics were influenced by host materials characteristics, with blue and yellow emissions being fine-tuned to produce complementary colors. This study highlights the critical role of charge mobility balance in the emissive layer and demonstrates the potential of independently optimizing blue and yellow TADF components for high-performance WOLEDs suitable for indoor 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.

Investigation of ultrasmall sidewall-insulated GaN via with large aspect ratio for the strategy of vertically stacked full-color Micro-LEDs

Micro light-emitting diode (Micro-LED) is considered as an ideal candidate for near-eye, outdoor display, and light field photography applications. At present, the commercialization of full-color Micro-LED is limited by the mass transfer of red, green, and blue (R-B-G) sub-pixels. Hence, we proposed a full-color scheme of vertically stacked tricolor Micro-LED layers to avoid mass transfer, which owns over 1000 PPI (pixel per inch). In this solution, the sidewall-insulated via in the epilayer plays a critical role to achieve the electrical and mechanical integration of three monochromatic Micro-LEDs with Si-based complementary metal-oxide semiconductor (CMOS) driver. Therefore, the via processes of GaN-based epilayer were investigated systematically using available semiconductor processes in this article. The inductively coupled plasma (ICP) etching was employed to create the ultra-small micro-structure array using SiO2 thin film as hard mask. Sidewall-insulated vias were fabricated with different aperture sizes (9.3, 7.5, and 3.4 μm) and a depth of about 4-μm. The vias with large aspect ratio are completely satisfy the requirement of designed vertical interconnection. This study aims to provide valuable reference for the commercial progress of high-resolution and full-color Micro-LEDs.

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.