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Improved photovoltaic performance of perovskite solar cells by utilizing down-conversion NaYF <sub/>4</sub> :Eu <sup>3+</sup> nanophosphors
摘要： Perovskite solar cells assembled with titanium dioxide electron transport layer exhibited brilliant photovoltaic properties due to titanium dioxide having a high electron mobility, appropriate energy level alignment and easy fabrication procedure. However, inherent instability exists in titanium dioxide-based perovskite solar cells because of the ultraviolet photocatalytic activity of titanium dioxide. This results in recombination at the interface of titanium dioxide/perovskite. In this report, the down-conversion nanocrystals film made of europium-doped sodium yttrium fluoride was deposited on the non-conducting side of the conducting glass. The down-conversion nanocrystal layer could absorb high energy ultraviolet photons and converted them to visible light. The layer not only extended the spectral response range for perovskite solar cells but also alleviated the photocatalytic activity of titanium dioxide. The perovskite solar cells with the down-conversion nanocrystals film generated average power conversion efficiency yield of 19.99%, which is much better than that of the device without the down-conversion nanocrystals film (16.99%). The best power conversion efficiency for the device with the down-conversion nanocrystals film was 20.17%. In addition, perovskite solar cells with the down-conversion nanocrystals film showed a small hysteresis.
关键词： titanium dioxide,down-conversion,NaYF4:Eu3+ nanophosphors,photovoltaic performance,perovskite solar cells
更新于2025-11-14 17:04:02
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Luminescence properties in relation to controllable morphologies of Ba <sub/>3</sub> [Ge <sub/>2</sub> B <sub/>7</sub> O <sub/>16</sub> (OH) <sub/>2</sub> ](OH)(H <sub/>2</sub> O):Eu <sup>3+</sup> and its thermal conversion product Ba <sub/>3</sub> Ge <sub/>2</sub> B <sub/>6</sub> O <sub/>16</sub> :Eu <sup>3+</sup>
摘要： Luminescence properties in relation to controllable morphologies of Ba3[Ge2B7O16(OH)2](OH)(H2O):Eu3+ and its thermal conversion product Ba3Ge2B6O16:Eu3+ were investigated. Three types of morphologies of Eu3+-doped Ba3[Ge2B7O16(OH)2](OH)(H2O) phosphors were obtained via hydrothermal reactions by different kinds of raw materials. In addition, Ba3Ge2B6O16:Eu3+ phosphors were obtained by calcining the precursor Ba3[Ge2B7O16(OH)2](OH)(H2O):Eu3+. The structure and morphology of the obtained samples were characterized by XRD, EDS, FT-IR, TG-DTA, SEM and HRTEM. Herein, the effects of the synthesis parameters, including the reaction temperature, boron sources and the dosage, doping of rare earth on the photoluminescence (PL) properties of Ba3[Ge2B7O16(OH)2](OH)(H2O) were investigated in detail. The lifetime and absolute quantum yield (QY) of different morphologies of Ba3[Ge2B7O16(OH)2](OH)(H2O):Eu3+ were also measured. The PL properties of the Ba3Ge2B6O16:Eu3+ phosphor prepared by the precursor calcination method compared with those prepared by the high-temperature solid-state method are discussed.
关键词： Morphologies,Eu3+ doping,Hydrothermal,Borogermanates,Phosphors,Luminescence
更新于2025-11-14 17:04:02
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A development of new red phosphor based on europium doped as well as substituted Barium Lanthanum Aluminate (BaLaAlO4: Eu3+)
摘要： New red emitting Eu3+ doped and substituted BaLaAlO4 phosphor powders were synthesized by simple modified solid state reaction method. BaLaAlO4 crystal phase formation studied through powder X-ray diffraction (XRD) analysis. Fourier Transform - Infra Red (FT-IR) analysis was performed to study the formation of the host with respect to temperature increment and metal-oxygen bond vibrations of BaLaAlO4 host lattice. Morphology of the phosphor was appeared as irregular in shapes with agglomeration. Photoluminescence (PL) analysis was performed to study the PL excitation and emission characteristics of the phosphor. It dictates that synthesized phosphors exhibited a strong red emission at 626 nm. Substitution effect of Eu3+ in BaLaAlO4 with various compositions such as Ba(1-x)LaAlO4: Eux3+, BaLa(1-y)AlO4: Euy3+ and BaLaAl(1-z)O4: Euz3+ were studied for PL enhancement. Luminescence decay time of the phosphors was also determined. PL thermal quenching and Commission Internationale de l'Eclairage (CIE) chromaticity analysis were carried out to find thermal stability and colour purity of the phosphor sample respectively. The Judd- Ofelt parameters (Ω2 & Ω4) obtained from the emission spectra of Eu3+ ions in BaLaAlO4 host lattice were evaluated and discussed.
关键词： BaLaAlO4,Eu3+,Red phosphor,Substitution effect,Solid state reaction
更新于2025-11-14 15:13:28
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Luminescence properties of novel Eu <sup>3+</sup> ‐doped tantalate NaCaTiTaO <sub/>6</sub> red‐emitting phosphors for solid‐state lighting
摘要： A novel tantalate red-emitting phosphors NaCa1-xEuxTiTaO6 (x = 0.02-0.50) is synthesized via the traditional solid-state reaction sintering. The photoluminescence properties, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermal stability are characterized in detail. Photoluminescence spectra show strong red emission monitored at 614 nm at λex = 395 nm. The spectral properties exhibit excellent color purity, chromaticity coordinate (CIE) characteristics. White light emitting diodes (w-LEDs) device are fabricated by the prepared phosphors and show high quality of color-rendering index. The investigated results suggest that the Eu3+-doped NaCaTiTaO6 phosphors can be as potential substitute red phosphors for w-LEDs.
关键词： Phosphors,Tantalate,NaCaTiTaO6:Eu3+,Luminescence
更新于2025-11-14 15:13:28
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Amine salts assisted controllable synthesis of the YVO4:Eu3+ nanocrystallines and their Luminescence properties
摘要： The Eu3+ doped YVO4 nanocrystallines with various morphologies were successfully synthesized by an amines (TETA, ETA and EDA) assisted hydrothermal process. By rationally adjusting the adding amount of TETA, ETA and EDA, the trepang-like, globular-like and pineapple-like Eu3+ doped YVO4 nanostructures can be conventionally obtained. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD patterns indicate that these samples are all of the tetragonal structure. The SEM and TEM results show that the amines additives play an important role in morphology formation. Furthermore, the fluorescence properties of those samples are also systematically studied. Under the excitation of 280 nm, Eu3+ doped YVO4: nanostructures emit strong red fluorescence due to the transitions of 5D1-7F1 and 5D0-7FJ (J =1, 2, 3 and 4) of Eu3+ ions. The intensity of red fluorescence is related to not only the concentrations of Eu3+, but also the types of adding amines. The effective luminescence lifetimes of the trepang-like Y0.9Eu0.1VO4 nanocrystallines, the globular-lik and pineapple-like Y0.95Eu0.05VO4 nanocrystallines are 0.91 ms, 1.02 ms and 1.14 ms, respectively. It is believed that this study is beneficial to promote the development of color display industry.
关键词： hydrothermal,Amine salts,luminescence lifetimes,Eu3+ doped YVO4,fluorescence properties
更新于2025-09-23 15:23:52
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Preparation and Enhancement of Luminescent Intensity of New Rare Earth Molybdate NaLa(MoO4)2:Eu3+ Phosphors
摘要： Novel red-emitting rare earth molybdate phosphors NaLa(MoO4)2:Eu3+ have been successfully synthesized by sol-gel method assisted by microwave. The as-synthesized samples were characterized by means of Fourier transform infrared spectroscopy, X-ray diffraction and Fluorescence spectrophotometer, respectively. The results show that the target product NaLa(MoO4)2:Eu3+ have been synthesized by calcining precursor at 800 oC. The obtained samples belong to tetragonal Scheelite-structure and I41/a space group. The excitation spectrum of NaLa(MoO4)2:Eu3+ has a broad band in the range of 250-350 nm and the main peak is at 301 nm. The broad band can be ascribed to the charge transfer band of Mo-O and Eu-O. The sharp lines in 350-500 nm range are due to 4f-4f transitions of Eu3+. The emission spectrum contains a series of narrow peaks, with the main peak at 616 nm originated from the electric dipole transition of 5D0 → 7F2 of Eu3+. The appropriate doping amount of Bi3+ and flux NH4F can enhance luminescent intensity of the sample effectively.
关键词： Rare earth molybdate,Sol-gel method assisted by microwave,Red-emitting phosphors,NaLa(MoO4)2:Eu3+
更新于2025-09-23 15:23:52
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Sol-Gel Template Synthesis and Characterization of Lu2O3:Eu3+ Nanowire Arrays
摘要： Uniform Lu2O3:Eu3+ nanowire arrays were successfully prepared by the sol-gel process using anodic aluminum oxide (AAO) templates. The as-synthesized nanowires are homogeneous, highly ordered, and dense and have a uniform diameter of ~300 nm defined by the AAO templates. The X-ray diffraction and selected area electron diffraction results show that the Lu2O3:Eu3+ nanowires have a polycrystalline cubic structure, and the crystallite size of the Lu2O3:Eu3+ nanowires is confined by the AAO template. The nanowires within the AAO template showed good photoluminescence and X-ray-excited optical luminescence performances for Lu2O3:Eu3+. The emission peaks were attributed to the 5D0 → 7FJ transitions of Eu3+ (J = 0, 1, 2, 3).
关键词： sol-gel method,nanowire arrays,Lu2O3:Eu3+,anodic aluminum oxide (AAO)
更新于2025-09-23 15:23:52
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Influences of sol-gel progress on luminescent properties of Li <sub/>1.0</sub> Nb <sub/>0.6</sub> Ti <sub/>0.5</sub> O <sub/>3</sub> :Eu <sup>3+</sup> red phosphor
摘要： Li1.0Nb0.6Ti0.5O3:3wt.%Eu3+ red phosphor was synthesized by sol-gel method. The influences of the pH value and the citric acid(CA)/ metal cations(M) ratio on the luminescent properties of the samples were discussed. The properties of the samples were characterized by X-ray diffraction(XRD) and photoluminescence spectroscopy, respectively. The results showed that the samples were consist of “M- phase”. Under the 466nm excitation, the orange emission at 592nm and the red emission at 612nm could be observed. The emission intensity increased with the increasing of pH value firstly and then decreased. The optimum pH value was 5.5. Moreover, the emission intensity decreased with the increasing of CA/M ratio. The relatively high emission intensity of the sample could be obtained when the CA/M was 3:1. Emission spectra and CIE coordinate of Li1.0Nb0.6Ti0.5O3:3wt.% Eu3+ were superior to commercial red phosphor Y2O3:Eu3+,which showed the red phosphor could have potential application in the White-LED field.
关键词： the red phosphor,Eu3+-doped,emission spectrum,Sol-gel method
更新于2025-09-23 15:23:52
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Investigation on electronic structure and luminescence mechanism of CaF2:Eu3+ from first principles calculations
摘要： In this work, we present the results of theoretical calculations based on the density functional theory (DFT) of structural, electronic and optical properties of CaF2 crystal doped with Eu3+ ion. This study covers both ground and excited states of considered material by ?xing spin magnetic moment 6μB and 4μB, respectively. The Eu3+ doping induces slight displacement of its nearest neighbors. The presence of Eu3+ ion is con?rmed by the calculated charge density and magnetic moment. Some electronic states belonging to 4f orbital are found in the forbidden energy region of CaF2 and the spin ?ipping of one 4f electron of Eu3+ caused by the excitation is demonstrated by means of the computed electronic properties. The absorption spectra of CaF2:Eu3+ is calculated and compared with that of pure CaF2. Finally, the possible mechanism of luminescence is proposed based on the obtained electronic and optical properties.
关键词： CaF2:Eu3+,First principles study,Electronic structure,Luminescence
更新于2025-09-23 15:22:29
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The influence of Eu3+ concentration on the spectroscopic properties of YAG:Ti, Eu3+ nanocrystalline luminescent thermometer
摘要： The influence of Eu3+ co-dopant on the luminescent properties of an yttrium aluminum garnet co-doped with titanium and europium ions (YAG: Ti, Eu) nanocrystals has been investigated. This is a continuation of the search for novel materials suitable for luminescence thermometry using an approach based on inorganic nanocrystals co-doped with transition metal ions and lanthanides. The optical response of Ti3+, Ti4+ and Eu3+ ions present in the examined structures was analyzed in a wide range of temperatures. A model of distribution of energy levels of these ions explaining the observed spectra and their dependence on the Eu concentration was proposed. Moreover, the possibility of energy transfers between these ions and their dependence on the concentration of Eu ions and on the temperature was indicated. On this basis, a model was proposed, allowing for the optimization of the maximum sensitivity and the corresponding temperature.
关键词： Titanium,Luminescent thermometry,Europium,Eu3+,Nanocrystals
更新于2025-09-23 15:22:29