- 标题
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Effect of fluxes on luminescence properties of color-tunable Ba1.3Ca0.7SiO4:Eu2+, Mn2+ Phosphor for Near-Ultraviolet White-LEDs
摘要： Eu2+/Mn2+-codoped Ba1.3Ca0.7SiO4 (BCS), a promising single-phase and white-light-emitting phosphor, is prepared by the solid-state reaction at a calcination temperature of 1000 °C for 2 h by adding SrCl2, CaCl2, KCl, NaCl, NH4Cl, Li2CO3, BaF2, CaF2, and BaCl2 as fluxes. The samples are characterized by X-ray diffraction and photoluminescence spectroscopy. The emission wavelength and color-rendering index (CRI) can be tuned by adjusting the amount of the BaCl2 flux and are influenced by the different flux types. NH4Cl exhibits the best fluxing effect for the Mn2+ ion doping probably because the formed eutectic mixtures of BaCl2–CaCl2 during the reaction process promote the reaction. The phosphors produced by adding a SrCl2 flux exhibit the highest CRI of 87.2 with Commision International de I’Eclairage (CIE) chromaticity coordinates of (0.347, 0.343) in the white region under near-ultraviolet light excitation.
关键词： Mn2+ ion,Color-tunable,Fluxing effect,Single-phase
更新于2025-09-19 17:13:59
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Hybrid Color-Tunable Polymer Light-Emitting Diodes Using Electrospraying
摘要： This paper proposes a new paradigm in polymer light-emitting diode (PLED) fabrication by using a uniform electrosprayed microparticle film as the active layer. Among the seven electrospraying parameters analyzed, three crucial parameters are statistically identified and optimized to obtain thin electrosprayed microparticle layers. Using optimized electrospraying conditions, single-color red-emitting PLED (MEH-PPV) with a peak current density of 16.1 mA/mm2 under a 13.5 V bias and a peak external quantum efficiency of 3.2% are successfully fabricated. Finally, a combinatorial approach is implemented using both MEH-PPV (red-emitting) and F8BT (green-emitting) polymer microparticles at different mixing ratios to tune the emission spectrum of the devices. As such, it has been demonstrated that hybrid multilayer films using different organic materials with nonorthogonal solvents can be produced using this new approach. The parameter analysis and color-tunable properties pave the way towards white light PLED fabrication.
关键词： polymer light-emitting diode,F8BT,electrospraying,PLED,MEH-PPV,color-tunable
更新于2025-09-12 10:27:22
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In-Planar-Electrodes Organic Light-Emitting Devices for Smart Lighting Applications
摘要： Smart lighting systems have earned an irreplaceable position in fields such as health care, communication, and garden cultivation. Inorganic light-emitting diode (LED) illuminant, as a traditional and well-developed field, is suitable for smart lighting systems and widely researched. However, smart lighting systems with organic light-emitting device (OLED) illuminant are rare. The key issue is to fabricate an efficient OLED illuminant with tunable spectra and intensity. Here, in-planar-electrodes OLEDs (IPE-OLEDs), which could be a possible solution to OLED illuminant used in smart lighting systems, is presented. By utilizing Mg:Ag thin film to connect two regular OLEDs with novel electron transporting layer, efficient and easy-to-fabricate IPE-OLEDs with high brightness and low voltage are achieved. The working mechanism of the IPE-OLEDs is discussed. The IPE-OLEDs can be easily driven with alternating current signals to independently address each emissive sub-cell. Thus, the OLED illuminant based on IPE-OLEDs enables adjustment of color temperature and intensity. To exhibit the features of the fabricated IPE-OLEDs further, a simple but effective smart lighting system containing IPE-OLEDs and gas detector is constructed, which could be used in the mining industry.
关键词： planar electrodes,OLEDs,color-tunable,alternating current,smart lighting
更新于2025-09-10 09:29:36
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The synthesis and luminescent properties of Dy/Re (Re?=?Tb or Eu) co-doped Gd2(WO4)3 phosphor with tunable color via energy transfer
摘要： The new systems of the (Gd0.95-xDy0.05Tbx)2(WO4)3 (x = 0–0.1) and (Gd0.95-yDy0.05Euy)2(WO4)3 (y = 0–0.2) phosphors have been successfully obtained using the hydrothermal method at 900 °C in this work. The crystal structure, morphology, PL/PLE spectra, ?uorescence and decay analysis have been studied in detail via the combined techniques of XRD, FE-SEM, PLE/PL spectra and decay kinetic. The phase-pure of the (Gd0.95-xDy0.05Tbx)2(WO4)3 and (Gd0.95-yDy0.05Euy)2(WO4)3 with good dispersions have been formed at the lower sintering temperature of 900 °C. Under 273 nm and 270 nm excitation (the 6P7/2→8S7/2 transitions of Gd3+), the Gd2(WO4)3:Dy3+/Tb3+ and Gd2(WO4)3:Dy3+/Eu3+ phosphors exhibit both Dy3+ (yellow, at 574 nm) and Tb3+ (green, at 547 nm) as well as Dy3+ (yellow, at 574 nm) and Eu3+ (red, at 616 nm) emissions, respectively. The presences of WO4 2-, Gd3+ and Dy3+ excitation bands on the PLE spectra by monitoring the Tb3+ and Eu3+ emissions directly provide an evidence of energy transfer of WO4 2-→Tb3+, Gd3+→Tb3+ and Dy3+→Tb3+, as well as WO4 2-→Eu3+, Gd3+→Eu3+ and Dy3+→Eu3+, respectively. The quenching concentrations of both two systems are determined to be 7 at% (x = 0.07 for Tb3+) and 10 at% (y = 0.10 for Eu3+), and the quenching mechanisms of both two systems are mainly due to the Tb3+-Tb3+ and Eu3+-Eu3+ energy transfers, respectively. The color-tunable emission can be achieved though adjusting the relative content ratios of Dy3+/Tb3+ or Dy3+/Eu3+, which has been veri?ed by the CIE chromaticity coordinates analysis. The energy transfer e?ciencies of Dy3+→Tb3+ and Dy3+→Eu3+ have been calculated, and the energy transfer mechanisms have been analyzed in detail. The (Gd0.95-xDy0.05Tbx)2(WO4)3 and (Gd0.95-yDy0.05Euy)2(WO4)3 phosphors with color-tunable emission may have a potential application for w-LEDs.
关键词： Color-tunable emission,Gd2(WO4)3:Dy3+/Tb3+,Gd2(WO4)3:Dy3+/Eu3+,Luminescent property
更新于2025-09-10 09:29:36
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Color-tunable and upconversion luminescence of Gd2O2S:Er,Tm phosphor: experimental investigations and first-principles calculation
摘要： The Er3+, Tm3+ co-doped gadolinium oxysulfide phosphors were prepared using solid-state reaction in vacuum. The crystal structure, morphology, and photoluminescence characteristics were, respectively, investigated by X-ray diffraction, transmission electron microscope, upconversion luminescence spectra and Commission Internationale de L’Eclairage diagram. Under 980 nm excitation, the quenching concentration of Er3+ was revealed to be 7 mol% with highest luminescence intensity and fluorescence lifetime. The emitting color of Gd2O2S:Er,Tm phosphors can be tuned by adjusting the concentration of Er3+ and Tm3+. First-principles calculation was employed to clarify the luminescence mechanism of the impurities doped in gadolinium oxysulfide host lattice by calculated band structure, density of states and absorption spectrum.
关键词： first-principles calculation,color-tunable,Gd2O2S:Er,upconversion luminescence,Tm
更新于2025-09-04 15:30:14