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Circularly Polarized Rooma??Temperature Phosphorescence and Encapsulation Engineering for MOFa??Based Fluorescent/Phosphorescent WLEDs
摘要： Optical materials with circularly polarized luminescence and room temperature phosphorescence currently attract great attention owing to their unique optoelectronic properties. Herein, via the coordination-induced assembly strategy, a homochiral metal–organic framework (MOF) 1 with high stability and porosity is successfully synthesized by using the achiral triphenylamine-based molecule as the building block. Remarkably, MOF 1 shows circularly polarized luminescence and phosphorescence at room temperature simultaneously, also with excellent anisotropic optical properties. Furthermore, MOF 1 can serve as a nanocontainer to construct dye-encapsulated host–guest systems. Importantly, the multicolor emissions including white-light emission can be achieved. The corresponding color rendering index and correlated color temperature values of light emitting device are 73 and 5541 K, when using dye-loaded MOF 1?RhB 10 (CIE: 0.33, 0.33) as single-phase white light-emitting phosphor. This study first reports circularly polarized phosphorescence based on MOF without precious metals under ambient conditions, and also is first time for phosphorescent polarized materials with high porosity. These results will open up a new pathway to the design of porous chiroptical materials and white-light materials.
关键词： circularly polarized luminescence,host–guest system,room temperature phosphorescence,white light emitting devices,metal–organic frameworks
更新于2025-09-23 15:21:01
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Synthesis of Silica-Coated Csa??PbBra?? and Csa??Pb(Br0.4I0.6)a?? Quantum Dots With Long Lifetime and Enhancement in Quantum Efficiency for WLEDs Applications: Lightings With High CRI and Displays With Wide Color Gamut
摘要： To focus on developing white light-emitting diodes (WLEDs) for lightings with high color rendering index (CRI), low correlated color temperature (CCT), and the displays with wide color gamut, inorganic perovskite quantum dots (QDs) such as CsPbX3 (X = Cl, Br, I) were the promising candidate owing to the excellent optoelectronic properties such as high quantum efficiency, narrow emission wavelengths, and tunable emission spectrum. Nevertheless, the CsPbBr3QDs in the form of powders or films had a poor air stability and severe decline of quantum efficiency. Therefore, in this article, a new idea was proposed that 0-D green–red perovskite QDs powders such as Cs4PbBr6 and Cs4Pb(Br0.4I0.6)6 with improved quantum efficiency and long lifetime were first developed by silica-coated method and crystal phase transition in low-temperature synthesis. The quantum efficiency in green Cs4PbBr6 powders could be significantly enhanced from 31.41% to 45.87% and red Cs4Pb(Br0.4I0.6)6 powders was 22.79%. Moreover, the as-prepared perovskite QD powders and commercial YAG phosphors combined with blue chips were applied to high-quality WLEDs for lightings and displays. More importantly, the as-fabricated wide Commission Internationale de l’Eclairage (CIE) color gamut WLEDs for displays possessed 115% National Television System Committee (NTSC) coverage rate and luminous efficiency of 51 lm/W under 20-mA driving current. On the other hand, the constructed WLEDs for high-power lightings would generate a warm white light with a luminous efficiency of 38 lm/W, extremely high CRI of 92.8, and low CCT of 3828 K under 350 mA. Hence, the proposed green–red perovskite QD powders had outstanding potential applications in WLEDs.
关键词： white light-emitting diodes (WLEDs),0-D perovskite quantum dots (QDs),backlights of displays,solid-state lightings
更新于2025-09-23 15:21:01
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High color rendering index white light-emitting diode based on enviromental friendly carbon and AIZS nanoparticles
摘要： Solid-state white light-emitting diodes (WLEDs) based on carbon dots (CDs) have attracted broad attention due to their high brightness and enviromental friendly. However, the poor performance including low efficiency and weak emission of red-emitting CDs further hindered its application on WLED devices. Herein, we constructed one outstanding WLEDs device by combining carbon dots (blue emission, green emission) and Ag-In-Zn-S (AIZS) nanoparticles with red emission. Moreover, by adjusting the volume ratio of the three materials, the WLED showed maximum color rendering index (CRI) of 97 and maintained CRI value above 90 during the correlated color temperature (CCT) tuned from 3387 to 8018 K. Meanwhile, the as-fabricated WLED devices showed excellent color rendering stability during the working voltages from 3.0V to 3.5V. This work may provide one new avenue for development of low-cost, environmental friendly and high-performance CDs phosphor-based WLEDs.
关键词： AIZS nanoparticles,color rendering index,white light-emitting diode,carbon dots,environmental friendly
更新于2025-09-23 15:21:01
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Synthesis and photoluminescence properties of Ca4La6(PO4)2(SiO4)4O2: Dy3+ phosphor with high thermal stability for white light-emitting diodes
摘要： Novel yellow emitting Ca4La6(PO4)2(SiO4)4O2: Dy3+ phosphors were synthesized by high-temperature solid-state reaction method. The crystal structure, diffuse reflection, photoluminescence, and photoluminescence excitation spectra, decay curves, as well as thermal stability were investigated in detail. Under 346?nm excitation, the phosphor exhibits two strong emission peaks at 479?nm and 585?nm, with the CIE coordinates located in the yellow region. When heated up to 150?°C, the Ca4La6(PO4)2(SiO4)4O2: 0.06Dy3+ phosphor still has 83% of the initial PL intensity at room temperature, indicating its high thermal stability. The results suggest that the as-prepared Ca4La6(PO4)2(SiO4)4O2: Dy3+ phosphor could serve as a promising candidate for near-ultraviolet white light-emitting diodes.
关键词： photoluminescence,Ca4La6(PO4)2(SiO4)4O2:Dy3+,thermal stability,white light-emitting diodes,phosphor
更新于2025-09-23 15:21:01
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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