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- 实验方案
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Tunable Chromaticity and High Color Rendering Index of WLEDs with CaAlSiN <sub/>3</sub> :Eu <sup>2+</sup> and YAG:Ce <sup>3+</sup> Dual Phosphora??ina??silicaa??glass
摘要： Phosphors-in-glass (PiG), which serves as a potential bi-replacement of both phosphors and organic encapsulants in high-power white light-emitting diodes (WLEDs), has captured much attention due to its high thermal stability and excellent luminescent properties. However, due to the high temperature-sensitivity and the chemical reactions between phosphors with glass matrix, a variety of phosphors, especially red phosphors could be hardly dispersed into the glass without thermal quenching and decomposition, which greatly limits the improvement of color rendering index and chromaticity tunability of the WLEDs. In this study, adopting the mesoporous silica (FDU-12) and commercial phosphors as raw materials, the phosphors-in-silica-glasses (PiSGs) embedded with red phosphor CaAlSiN3:Eu2+ and yellow phosphor YAG:Ce3+ have been successfully prepared at low sintering temperature (950 ?C) and short preparation time (10 min) using spark plasma sintering. Owing to the well preservation of the originally emissive properties of the embedded phosphors, the warm WLEDs with tunable chromaticity and exhibited a superior performance with LE of 133 lm/W, CCT of 3970 K and CRI of 81 were fabricated by encapsulating the as-prepared PiSGs on the blue chips. Moreover, the PiSG composite exhibits a high thermal conductivity up to 1.6 W/m·K.
关键词： white light-emitting diodes,phosphor in silica glass,tunable chromaticity,mesoporous silica
更新于2025-09-23 15:21:01
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Tunable luminescence and morphological evolution of facile synthesized zinc borate/carbon dots composites for NUV-WLEDs
摘要： A series of zinc borate/carbon dots composites (ZBH/yNCDs) were successfully synthesized under hydrothermal conditions. The influences of yellow N-doped carbon dots (yNCDs) content on the structure, morphologies and luminescence properties of the zinc borate (4ZnO·B2O3·H2O, ZBH) were investigated. With increasing yNCDs content, ZBH in the ZBH/yNCDs composites gradually lost water and eventually became ZB/yNCDs (4ZnO·B2O3, ZB) composites. Meanwhile, the tunable luminescence of ZBH/yNCDs composites and the morphological evolution from rod-like to blocks to sphere-like were achieved by varying the yNCDs content in the zinc borate matrix. The results revealed that the ZBH/yNCDs composite with sphere-like morphology has the strongest white light emission at 395 nm excitation wavelength. Therefore, the ZBH/yNCDs composites may be used as phosphors in the near-ultraviolet (NUV) excitation white-light illumination field. The discovery of this work may also provide new inspirations for solving the self-quenching effect of carbon dots in the solid-state display applications.
关键词： N-doped carbon dots,White light-emitting diodes,Morphology,Zinc borate
更新于2025-09-23 15:21:01
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Mn-doped 2D Sn-based perovskites with energy transfer from self-trapped excitons to dopants for warm white light-emitting diodes
摘要： Mn-doped 2D perovskite powders are promising phosphors for warm white light-emitting diodes (LEDs). However, it remains a challenge to solve the problem of lead toxicity and improve photoluminescence quantum yields (PLQYs). Here, we have successfully prepared Mn-doped 2D Sn-based perovskite materials ((C8H17NH2)2Sn1-xMnxBr4). The PLQYs of (C8H17NH2)2Sn1-xMnxBr4 (x = 0.26) powders reach up to 42%. The as-prepared (C8H17NH2)2Sn1-xMnxBr4 exhibit a single broad photoluminescence (PL) band, differing from the dual peaks of Mn-doped lead halide perovskite quantum dots. Theoretical conclusions and experimental results show the competitive relationship between self-trapped excitons (STEs) emission from the host crystal and dopant Mn d-d transition emission. With Mn dopant concentration increasing, the PL spectra exhibit red shifts and the full width at half-maximum (FWHM) turns larger, which is constructive for warm white LEDs. The fabricated warm white LEDs based on (C8H17NH2)2Sn1-xMnxBr4 show warm white light correlated color temperature (CCT, 3542 K) and high color-rendering index (Ra, 88.12). Our work provides new possibilities for optoelectronic devices based on lead-free perovskite materials.
关键词： self-trapped excitons,Mn-doped,photoluminescence quantum yields,2D Sn-based perovskites,warm white light-emitting diodes
更新于2025-09-23 15:21:01
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Systematic studies on Sr4La6(SiO4)6M2:Eu3+ (M?=?F/Cl) phosphors: effects of the halogen anions on photoluminescence
摘要： We successfully prepared Sr4La6(SiO4)6F2:Eu3+ (SLSOF:Eu3+) and Sr4La6(SiO4)6Cl2:Eu3+ (SLSOC:Eu3+) oxyapatite phosphors via the traditional solid-state method. The phosphors’ structure and photoluminescence properties were investigated by scanning electron microscope (SEM), X-ray powder diffraction (XRD), photoluminescence (PL) spectroscopy, ultraviolet–visible spectra and temperature-dependent emission spectra. Among them, the irregular morphology of SLSOF and SLSOC particles was displayed by SEM images, and the phase formation of both sets of phosphors was illustrated by XRD analysis. Additionally, PL spectra indicated that the phosphor could be efficiently excited by the near ultraviolet (NUV) light, and then emitted shining red light, agreeing well with that the calculated color coordinates are within the red region. Comparatively, the luminescence intensity of SLSOF:Eu3+ is higher than that of SLSOC:Eu3+ on the basis of the greater electronegativity of F?, which directly leads to the enhancement of 5D0→7F2 transition. The temperature-dependent emission spectra indicated that samples have excellent thermal stability. Internal quantum efficiency value of phosphors were calculated. These results indicated that the halogen anions of these Sr4La6(SiO4)6M2:Eu3+ play important roles in their PL properties and both phosphors have great potential to serve as red emitting phosphor for NUV white light emitting diodes.
关键词： oxyapatite phosphors,Sr4La6(SiO4)6Cl2:Eu3+,white light emitting diodes,photoluminescence,Sr4La6(SiO4)6F2:Eu3+
更新于2025-09-23 15:21:01
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Tunable photoluminescence from YTaO4: Bi3+ for ultraviolet converted pc-WLED with high chromatic stability
摘要： To avoid the color drift of WLED at high temperature, it is significant to develop color stable luminescent materials. Herein we report on a phosphor YTaO4:Bi3+ with a stable blue emission upon ultraviolet excitations even as the temperature changes between 300 and 480 K. Upon excitations into host absorptions a tunable blue emission can be led from 400 nm to 450 nm due to the enhanced energy transfer efficiency from host to bismuth ions as the concentration of bismuth increases. As excitation scheme is modulated between 355 and 370 nm the white emission can be achieved in the compound of YTaO4 single doped with Bi3+, which has rarely been reported previously. For proof of concept the prototype WLEDs have been demonstrated with the phosphor YTaO4:Bi3+ and the 365 nm InGaN chips under different driving currents. Our findings make it possible for single phase white emitting phosphors activated by a single ion of Bi3+ for WLEDs, and also can inspire to develop WLED devices with high chromatic stability.
关键词： YTaO4:Bi3+,ultraviolet excitation,chromatic stability,white light emitting diodes,phosphor
更新于2025-09-23 15:19:57
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Controllable synthesis of all inorganic lead halide perovskite nanocrystals and white light-emitting diodes based on CsPbBr3 nanocrystals
摘要： The colloidal cesium lead halide perovskite nanocrystals (NCs) have attracted much attention over the past five years as a promising class of material with potential application in wide-color-gamut backlight display because of their high photoluminescence quantum yield (PLQY) and narrow-band emission (full-width at half-maximum, FWHM < 35 nm). To controllably synthesize perovskite NCs, the effects of reaction temperature and reaction time on structure, morphology, particle size and photoluminescence (PL) properties of the NCs were systematically investigated in this article. Based on these results, the formation kinetics of the perovskite NCs was analyzed and disclosed in further. Finally, a white light-emitting diode (WLED) was prepared by using synthesized CsPbBr3 NCs and K2SiF6:Mn4+ phosphors as the color converters. The WLED exhibits the bright white emission with a CIE chromaticity coordinate of (0.389, 0.376) and a wide color gamut of 123% of NTSC, indicating a potential application in the field of wide color gamut displays in the future.
关键词： Cesium lead halide perovskite,white light-emitting diodes,photoluminescent,hot-injection method,nanocrystals
更新于2025-09-23 15:19:57
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Facile, Gram-Scale and Eco-friendly Synthesis of Multi-Color Graphene Quantum Dots by Thermal-Driven Advanced Oxidation Process
摘要： Graphene quantum dots (GQDs) have been demonstrated of great potential and benefits in the fields of bioimaging and white light-emitting-diodes (WLEDs). However, it is still highly demanding at the current level to solve the dilemma of achieving high-yield GQDs of good quality and superior fluorescent property using low-cost sustainable and industrializable production procedure. In this work, we for the first time report the gram-scale synthesis of well-crystalline GQDs with ultra-small size based on thermal-driven Advanced Oxidation Process (AOP) under facile green hydrothermal conditions. The average yield calculated from 20 trials reached up to 60%, and the average size of the dots was measured to be ~3.7 nm. Furtherly, GQDs with the photoluminescence (PL) emission of blue, green, yellow, orange, and red have been prepared by expanding the π-conjugation and introducing graphite nitrogen in the carbon skeleton based on chemical structure engineering. The PL-tunable GQDs have an average size distribution of 2~5 nm and a lamellar structure of 2~6 layers. Structure analysis results have indicated that the red shift of PL emission is attributed to bandgap narrowing. This approach successfully converts the easily available and cheap precursor into high-valued products with great application potentials. The PL-tunable GQDs have been successfully used as fluorescent probes of good biocompatibility for in vitro/ in vivo bio-imaging and to produce highly-photostable white-light-emitting composite film with a quantum yield (QY) of 24%.
关键词： Gram-scale synthesis,White light-emitting-diodes,Photoluminescence,Bioimaging,Advanced Oxidation Process,Graphene quantum dots
更新于2025-09-19 17:13:59
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Highly Efficient Cyan-Green Emission in Self-Activated Rb <sub/>3</sub> RV <sub/>2</sub> O <sub/>8</sub> (R = Y, Lu) Vanadate Phosphors for Full-Spectrum White Light-Emitting Diodes (LEDs)
摘要： Phosphor-converted white-light-emitting diodes (pc-WLEDs) rely on combining a near-ultraviolet (n-UV) or blue chip with trichromatic and yellow-emitting phosphors. It is challenging to discover cyan-green-emitting (480?520 nm) phosphors for compensating the spectral gap and producing full-spectrum white light. In this work, we successfully discovered two unprecedented bright cyan-green emitting Rb3RV2O8 (R = Y, Lu) phosphors that gives emission bands centered at 500 nm upon 362 nm n-UV light excitation. Interestingly, the both self-activated compounds exhibit high internal quantum e?ciencies (IQEs) of 71% for Rb3YV2O8 and 85% for Rb3LuV2O8, respectively. Moreover, controllable emission color can be successfully tuned from cyan-green to orange-red across the warm white light region by design strategy of VO4 3? → Eu3+ energy transfer. The thermal quenching of as-prepared phosphors could be e?ectively mitigated by this design strategy. Finally, the as-fabricated n-UV (λ ex = 370 nm) pumped phosphor-converted (pc) W-LED devices utilizing Rb3RV2O8 (R = Y, Lu) along with commercial phosphors demonstrate well-distributed warm white light with high color-rendering index (CRI) of 91.9 and 93.5, and a low correlated color temperature (CCT) of 5095 and 4946 K. It suggests that the both vanadate phosphors have potential applications in full-spectrum pc-WLEDs.
关键词： cyan-green emission,self-activated,full-spectrum white light-emitting diodes,energy transfer,vanadate phosphors
更新于2025-09-19 17:13:59
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Highly Elastic and >200% Reversibly Stretchable Downa??Conversion White Lighta??Emitting Diodes Based on Quantum Dot Gel Emitters
摘要： Combining the characteristics of different materials offers exciting new opportunities for advanced applications in various fields. Herein, white light-emitting diodes (WLEDs) with >200% reversible stretchability are fabricated using six-color quantum dots (QDs) gel emitters. Stable aqueous-phase alloy core/shell QDs with high quantum yield are obtained via ligand exchange using a ternary solvent system. Transparent and highly stretchable gels with large pores are created by binary-solvent-based gelation at low temperatures. Importantly, the QDs and the gel originate from the same two solvents, which make the QDs highly compatible with the gelation process. Consequently, QDs of six different colors are incorporated into the gel without any property degradation. The excellent optical properties of the QDs in the liquid phase (e.g., 17% higher photoluminescence (PL) intensity) are retained in the gel phase. The QD gel (QDG) exhibits elastic deformation up to 200%, with uniform PL over the entire gel. A down-conversion WLED built using the QDG emitter produces cool white light with a color temperature of 6100 K, a color rendering index of 94, and a luminous efficacy of 72 lm W?1. In addition, the performance of the QDG-based WLED remains unchanged even after more than 1000 bending/stretching cycles.
关键词： white light emitting diodes,gels,mechanical reliability,form factors,quantum dots
更新于2025-09-19 17:13:59
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Preparation of CdTe superparticles for white light-emitting diodes without F?rster resonance energy transfer
摘要： Due to many unique and excellent optical properties, quantum dots (QDs) have been seen as one of the most promising color conversion materials in light-emitting diodes (LEDs). However, the F¨orster resonance energy transfer (FRET) among di?erent colored QDs always causes a signi?cant red-shift of the ?uorescence emission, impeding the fabrication of LEDs with predicted photoluminescence (PL) emission spectra. In this work, we take advantage of CdTe superparticles (SPs), which are assembled by CdTe QDs, as the color conversion materials for the fabrication of WLEDs. Because of their submicron size, the distance between QDs with di?erent emissions can be large enough to avoid the FRET process. More importantly, this method provides us with an opportunity to precisely design and regulate the PL emission spectra of LEDs. By easily overlapping the individual PL spectra of CdTe SPs with di?erent emissions, the certain ratio of their usage for fabricating LEDs with desired PL emission spectra is identi?ed. According to this idea, a WLED with a color rendering index (CRI) of 81, luminous e?cacy of 27 lm W(cid:1)1, and color coordinate at (0.33, 0.34) with the color temperature of 5742 K is achieved.
关键词： F¨orster resonance energy transfer,white light-emitting diodes,quantum dots,color conversion materials,CdTe superparticles
更新于2025-09-16 10:30:52