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Facile Preparation of Stable Solid-State Carbon Quantum Dots with Multi-Peak Emission
摘要： Aggregation-caused quenching (ACQ) effect, known as the main cause to restrain solid-state luminescence of carbon quantum dots (CQDs), hinders further application of CQDs in white light-emitting diodes (WLED). Here, a complex of CQDs and phthalimide crystals (CQDs/PC) was prepared through a one-step solvothermal method. CQDs/PC prevented CQDs from touching directly by embedding the CQDs in phthalimide crystal matrix in situ, which effectively reduced the ACQ effect. Furthermore, CQDs/PC exhibited multi-peak fluorescence spectra that span the green, yellow and orange spectral regions. Finally, a WLED fabricated based on CQDs/PC achieved a color-rendering index of 82 and a correlated color temperature of 5430 K. This work provides a quick and effective strategy to apply CQDs to WLED.
关键词： solid-state luminescence,multi-peak emission,yellow carbon quantum dots,white light-emitting diode
更新于2025-09-19 17:13:59
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Light-emitting diodes in dermatology: stimulation of wound healing
摘要： Low-level light therapy (LLLT), which is sometimes included in phototherapy, is an effective therapeutic strategy to improve wound healing and reduce pain, inflammation and swelling. Nowadays, new sources of light, such as light-emitting diodes (LEDs) with a broad range of wavelengths, are widely available. The biological effects promoted by LEDs are dependent on irradiation parameters, mainly wavelength and dose. This review article focuses on recent clinical trials using light-emitting diode low-level light therapy (LED-LLLT) for enhancing wound healing. In this article, we also cover the mechanisms of action of LLLT on cells and tissues and highlight the importance of defining optimum LLLT parameters for stimulation of wound healing.
关键词： phototherapy,light-emitting diode (LED),wound healing
更新于2025-09-19 17:13:59
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Recent advances in thermally activated delayed fluorescence for white OLEDs applications
摘要： Thermally activated delayed fluorescence (TADF) materials, which can harvest all excitons without utilizing any noble metals to emit light, are becoming the key cornerstone for developing the next generation of organic light-emitting diode (OLED) devices. In recent years, TADF materials are attracting numerous attentions as a new surge of research focuses on both science and industry owing to their high efficiency, low power consumption, and low production cost attributes when applied to white OLEDs. The design and application of TADF in WOLED devices have also experienced the rapid development in fundamental science and industrial technology perspectives. In the present review, the specific reverse intersystem crossing mechanism and evolution of TADF is outlined firstly, and then the latest research progress of TADF-WOLEDs is summarized and discussed. TADF/conventional fluorescence, TADF/phosphorescence, all TADF and TADF exciplex-based WOLEDs are categorized and elaborated in terms of the device structure, working mechanism, efficiency, color-rendering index, etc. Finally, we conclude with the future challenges and opportunities in high-quality TADF devices and application area.
关键词： Thermally activated delayed fluorescence,exciplex,OLED,TADF,RISC,white OLEDs,organic light-emitting diode,reverse intersystem crossing
更新于2025-09-19 17:13:59
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Design of a high-efficiency system with combined reflectors for a light-emitting diode front fog lamp
摘要： This paper provides a design method for a light-emitting diode front fog lamp system based on a freeform surface and an improved quadric surface. First, a light-receiving reflector is used to converge the light-emitting diode beam to form an equivalent lighting point. Then, the relationship between the point and the light pattern on the work surface is calculated, and the freeform surface is constructed based on Snell’s law and non-imaging optical theory. Finally, two compensated reflectors are added at both ends of the freeform surface to reflect the unutilized light to achieve the compensation effect. By application of combined reflectors, the light pattern at the work surface 25 m away can satisfy the requirement of ECE R19 Revision 7. Also, this system has the advantages of small size and high efficiency because lens or prism groups are avoided. And the utilization of a compensated surface also increases light efficiency. Finally, a prototype model is tested, which also meets the regulatory requirements.
关键词： freeform surface,front fog lamp,combined reflectors,light-emitting diode,high efficiency
更新于2025-09-19 17:13:59
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Properties of indirect composites polymerized with laboratory light-emitting diode units
摘要： This study evaluated the light intensity of light-emitting diode (LED) units and the effects of five laboratory polymerization units on hardness and flexural strength. Two indirect composite materials (Cesead N and Solidex Hardura) were polymerized with five units (α-Light II, Hyper LII, LED Cure Master, Twinkle LED, and α-Light V). The light intensity of the devices was measured with a spectroradiometer. After light exposure, Knoop hardness number, flexural strength, and elastic modulus were determined. Evaluation of light intensity, using a wavelength range of 400 to 500 nm, revealed that the α-Light V and Hyper LII units had the highest light intensity. For the top surface of the two composites, the Knoop hardness number was significantly higher for the α-Light V and Hyper LII. For the two composite materials, flexural strength did not differ among the five polymerizing units. The present results indicate that the Cesead N and Solidex Hardura composites can be adequately polymerized with laboratory LED units.
关键词： microhardness,light source,light emitting diode,indirect composite,laboratory light polymerization
更新于2025-09-16 10:30:52
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Electro-optically efficient and thermally stable multilayer semitransparent pristine Ag cathode structure for top emission organic light emitting diodes
摘要： To attain high efficiency and stability in a top-emission organic light-emitting diode (TEOLED), the semitransparent metal cathode must have high transmittance, low absorbance, and uniform surface properties under continuous driving conditions. However, conventional semitransparent metal electrodes have numerous fundamental issues. Here, we report an electro-optically efficient and stable semitransparent pristine thin Ag cathode configuration for the high performances of TEOLED. A multilayer semitransparent cathode structure is fabricated by sandwiching a thin silver (Ag) layer between new organic wetting inducer and capping layer, 1,4-bis(2-phenyl-1,10-phenanthrolin-4-yl)benzene (p-bPPhenB). A thin Ag layer in the presence of p-bPPhenB exhibits superior optical and electrical properties including a high transmittance of 83.8% at 550 nm, low absorbance of 7.65% at 550 nm, and the low sheet resistance of 2.1 Ω/□, respectively, at room temperature and even under 110 OC for 100 hours. It is observed that our organic wetting inducer and capping layer, p-bPPhenB has considerable influence on the stabilization of surface properties of the thin Ag film by forming coordination bond between the Ag atoms and nitrogen atoms of p-bPPhenB through donating unshared electrons to the Ag atom. An optically optimized phosphorescent green TEOLED with this pure Ag cathode configuration enables a low driving voltage of 5.0 V at 10 mA/cm2 and remarkably high maximum current efficiency of about 167 cd/A compared with the Mg:Ag (10:1) cathode (5.4 V and 109 cd/A).
关键词： micro-cavity effect,organic wetting inducer,semitransparent pristine silver cathode,top-emitting organic light emitting diode,thermal stability
更新于2025-09-16 10:30:52
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Starburst-type triarylphosphine oxide trimers forming a stable amorphous n-type layer in solution-processed multilayer OLED
摘要： Novel starburst-type triphenylphosphine oxide trimers PO-1 and PO-2 were synthesized aimed at application as an electron-transporting material for multilayer organic light-emitting diodes (OLEDs). They showed high glass transition temperatures (Tg; 175 and 205 (cid:1)C, respectively) and high lowest triplet energies (T1; 2.81 and 2.78 eV, respectively). Their high solubility in 2-propanol allowed us to fabricate multilayer OLEDs by solution processing, and a double-emitting layer OLED consisting of poly(9-vinylcarbazole)-based p-type and PO-1-based n-type layers doped with a phosphorescent material (FIrpic) showed efficient sky-blue electroluminescence with a maximum external quantum efficiency of 9.33%.
关键词： Solution processing,Organic light-emitting diode,Phosphine oxide,Double emitting layer,Multilayer,Electron-transporting material
更新于2025-09-16 10:30:52
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Effects of B-Wave Ultraviolet Supplementation Using Light-Emitting Diodes on Caged Laying Hens during the Later Phase of the Laying Cycle
摘要： Caged laying hens are prone to calcium deficiencies, resulting in osteoporosis and egg quality deterioration during the later phase of the laying cycle. Fluorescent light and light-emitting diodes (LEDs), which are widely used in poultry houses now, are both deficient in ultraviolet (UV) light, the lack of which is detrimental to chickens’ welfare and health. This study was conducted to investigate the effects of UVB light supplementation using LEDs on the bone traits, blood parameters, laying performance, and egg quality for caged laying hens at 68–75 weeks. In total, 120 Jingfen laying hens were randomly assigned to four different groups, with three replicates in each group (10 hens in each cage as a replicate). UVB-LED lamps installed under the feed troughs were used to provide UVB light (296–316 nm) for the birds in the three treatment groups (1 h, 2 h, and 3 h UVB supplementation per day, respectively), while the control group was not exposed to UVB-LED light. Bone traits, egg quality, and amounts of calcium (Ca), phosphorus (P), 25-hydroxyvitamin D3 (25(OH)D3), 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), and 7-dehydrocholesterol (7-DHC) in both the serum and egg yolks were tested during the experiment. The results demonstrated that UVB-LED exposure significantly increased the bone mineral density (BMD), egg production, and yolk 1,25(OH)2D3 concentrations (p < 0.05), and reduced the content of serum 7-DHC (p < 0.05), especially in the 2 h/day group; however, it did not improve egg quality, vitamin D metabolites, or photoproducts in the serum and yolk 25(OH)2D3 concentrations (p > 0.05). This study concluded that UVB supplementation using LEDs had a positive effect on caged laying hens during the later phase of the laying cycle.
关键词： poultry,ultraviolet light-emitting diode,egg quality,light supplementation,bone quality
更新于2025-09-16 10:30:52
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Tunable LED Lighting with Five Channels of RGCWW for High Circadian and Visual Performances
摘要： In this study, red, green, cyan, warm white and cool white (RGCWW) LEDs are individually controlled to simulate dynamic daylight. The spectral power distributions (SPDs) are measured for both the daylight and the mixed white light. The correlated color temperature (CCT), circadian action factor (CAF) curves in the daytime of the mixed white LED almost overlap to those of daylight with a small error of about 1%. The CIE chromaticity coordinates of the mixed white light are distributed along the Planckian locus with a little deviation below 0.003. Also, its color rendering index (CRI) is above 90. The RGCWW five-chip LEDs of high circadian and visual performances will benefit to synchronize circadian rhythm in closed environment during long time without daylight, combined with better mood and alertness. The simulation errors and development trend of the mixed lighting are discussed.
关键词： mixed white light,circadian rhythm,circadian action factor,color rendering index,light emitting diode
更新于2025-09-16 10:30:52
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High efficiency color-temperature tunable organic light-emitting diode
摘要： In this study, we demonstrate a high-efficiency and high light-quality organic light-emitting diode (OLED) with color temperature tunable from the 1700 K of dusk-hue, 1900 K of candles and 2500 K of incandescent bulbs to 3000 K of warm-white light. The color-temperature tunable OLED device was achieved by utilizing a hybrid system and inserting a carrier modulation layer (CML) between the emission layers. In addition, the electron-rich charge transport properties of EML-1, facilitated via a 3 : 1 composition ratio of the 3P-T2T host to TPD-15 co-host, played a crucial role in tuning the desirable low-color temperature of the fabricated OLED devices. The current efficiency, power efficacy, and spectrum resemblance index (SRI) of the studied OLED are 40.2 cd/A, 40.3 lm W?1 and 82.2 at 1000 cd m?2, respectively. The resultant devices show great potential to advance the study and development of physiologically friendly lighting and enable a successful commercial OLED lighting product in the market.
关键词： organic light-emitting diode,physiologically friendly lighting,high light-quality,color temperature tunable,high efficiency
更新于2025-09-16 10:30:52