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Broad-band emission and color tuning of Eu3+-doped LiCa2SrMgV3O12 phosphors for warm white light-emitting diodes
摘要： In this study, series of Eu3+-doped LiCa2SrMgV3O12 (LCSMV) phosphors with broad-band emission and color tunable feature were prepared via solid phase reaction. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results presented a pure cubic phase product with micron-sized and homogeneous distribution of element. Their spectroscopic properties were investigated systematically by photoluminescence excitation (PLE) and emission (PL) spectra, temperature-dependent PL spectra and luminescence decay curves. The LCSMV phosphors displayed a strong absorption to ultraviolet light and a broad cyan emission. Moreover, in Eu3+-doped LCSMV phosphors, Eu3+ ion characteristic emissions at 589, 610, 651 and 705 nm, attributing to the 5D0→7F1, 7F2, 7F3 and 7F4 transitions, were observed. Along with Eu3+ ion concentrations increasing, the emission colors could be readily tuned from cyan to orange and the decay lifetimes of (VO4)3- became shorter. Meanwhile, electric dipole-dipole interaction was responsible to energy migration from (VO4)3- groups to Eu3+ ions. Further, the quantum efficiency (QE) values were estimated to be 32.5% for LCSMV host and 39.3% for LCSMV: 0.01Eu3+ sample. Finally, a LED lamp was prepared by integrating the blend of the LCSMV: 0.01Eu3+ phosphors and commercial blue-emitting BaMgAl10O17:Eu2+ phosphors with NUV chip (365 nm) and exhibited warm white light (CCT = 3655 K, Ra = 90), which may be applied in lighting and display field.
关键词： Self-activated luminescence,Color tunable,Light-emitting diode,Vanadate phosphor,Color rendering index,Broad-band emission
更新于2025-11-20 15:33:11
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Piezoluminescent devices by designing array structures
摘要： Mechanoluminescence has attracted increasing attentions because it can convert the kinetic energy during human daily motions into light to be used in sensors and displays. However, its practical applications are still hindered by the weak brightness and limited color while under large forces. Herein, we developed novel piezoluminescent devices (PLDs) which could effectively emit visible light under low pressing forces through the stress-concentration and enhancing deformation on the basis of carefully-designed array structures. The emitting colors were also tunable by using bilayer luminescent film under different pressures. This work not only provides a new strategy to effectively harvest mechanical energy into light, but also presents a scalable, low-cost and color-tunable PLD which shows great potentials in various applications such as luminescent floors, shoes and stress-activated displays.
关键词： mechanoluminescence,color-tunable,piezoluminescent device,array structure
更新于2025-09-23 15:23:52
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Ag-location-based color-tunable fluorescent AuAg nanoclusters for “turn-on” and “turn-off” detection of l-cysteine
摘要： The color-tunable AuAg nanoclusters (AuAg NCs) are designed by adjusting the location of Ag element, in which β-lactoglobulin (β-Lg) serves as the capping and reducing agent. The mono-metal Au NCs emit red-fluorescent emission (red-Au NCs@β-Lg); however, the stronger metallophilic interaction between Au and Ag facilitate the smaller size, and then the bimetal AuAg NCs@β-Lg present yellow emission (yellow-AuAg NCs@β-Lg). A "Ag+ shell" outside the AuAg NCs@β-Lg cause the emission change to orange (orange-AuAg NCs@β-Lg-Ag+). This is the first time for Ag+ to tune continuously the emission wavelength of AuAg NCs. TEM proves that the size of particle has a close relationship with the fluorescence emissions. L-cysteine (Cys) stabilized the protective effect of β-Lg and shows a "turn on" effect on the fluorescence intensity of yellow-AuAg NCs@β-Lg. In contrary, the strong interaction between Cys and Ag+ destroys the protection of β-Lg to the core of yellow-AuAg NCs@β-Lg and shows a distinct "turn off" effect on the fluorescence intensity of orange-AuAg NCs@β-Lg-Ag+. The above phenomenon has been successfully applied to the detection of Cys in the Hela cells. This location-based color-tunable strategy is expected to open up a new potential to improve the performance of NCs.
关键词： L-cysteine,Color-tunable,Ag-location,AuAg nanoclusters
更新于2025-09-23 15:22:29
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Upconversion luminescence properties of Y2O3: Yb3+/Er3+/Tm3+ nanocrystal doped PMMA nanocomposites
摘要： Y2O3 nanocrystals triply doped with Yb3+, Er3+, Tm3+ ions were synthesized via alginic acid-assisted gelation using thermal decomposition method and annealed at 800 °C for 24 h. Nanopowders were embedded into PMMA matrix via free-radical polymerization in an ultrasonic bath. X-ray diffraction and transmission electron microscopy measurements have shown that the crystal grain sizes decreased significantly with the narrow size distributions of the nanocrystals in PMMA matrix. A diode laser at 975 nm was used to measure the upconversion luminescence of the annealed nanopowders and those embedded in PMMA between the 400–850 nm wavelength region. The Er3+ concentration and the excitation power density dependencies of the relative intensities for red, green and blue upconversion luminescence in the nanopowder and PMMA nanocomposites are found to be different. The measured CIE-1931 color coordinates of the upconversion luminescence in PMMA nanocomposites show appreciable color stability under different excitation power densities, which is required for potential applications in the field of photonics.
关键词： Color Tunable Emission,Upconversion Luminescence,Polymer nanocomposites,Color Stability,Polymethyl methacrylate (PMMA)
更新于2025-09-23 15:21:21
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Design of color tunable thin film polymer solar cells for photovoltaics printing
摘要： Color tunable thin film polymer solar cells have demonstrated the potentials of a wide applications in photovoltaics printing, which is significant for ink pollution reduction and energy saving. This work presents a new effective approach to realize color-tuning photovoltaic cells with optical microcavity structures. Aluminum-doped zinc oxide is utilized as electron transport layer material. With its high electrical conductivity, the thickness tuning range can be quite large, which means the cavity length has a wide variation range. It thus provides sufficient space for optical thin film design to obtain multi colors. By the transfer matrix method, device reflection and absorption spectra are numerically investigated. Based on that, the optical principles for color tunability are explored. In further step, the relationship between device photovoltaics performance and reflective colors are also discussed. Finally, the color coordinates and luminosities are calculated. As results, the colors of the devices designed are capable to cover a relatively large region in Commission Internationale de l′Eclairage (CIE) 1931 x, y chromaticity diagram, which is available to be integrated into the advertisement poster boards, building wall printing and other display applications.
关键词： optical microcavity,thin film polymer solar cells,aluminum-doped zinc oxide,photovoltaics printing,color tunable
更新于2025-09-23 15:21:01
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Color tunable upconversion luminescence and optical thermometry properties of mixed Gd2O3:Yb3+/Ho3+/Er3+ nanoparticles prepared via laser ablation in liquid
摘要： The mixtures of Gd2O3:Yb3+/Er3+ and Gd2O3:Yb3+/Ho3+ nanoparticles were successfully prepared via pulsed laser ablation in liquid followed by solution mixing. Under excitation of 980 nm diode laser, tunable color from green to red emission was achieved. Based on the thermal linked energy levels, the temperature sensitive upconversion emission was observed. The fluorescence intensity ratio (FIR) of I513–530 nm/I530–580 nm increased as the elevation of temperature. The absolute sensitivity and relative sensitivity were derived from temperature dependent FIR. The results show that the mixture of Gd2O3:Yb3+/Er3+ and Gd2O3:Yb3+/Ho3+ nanoparticles are not only potential candidates for multicolor upconversion luminescence but also promising optical materials for non-contact optical thermometry.
关键词： Gd2O3 nanoparticles,Color tunable emission,Pulsed laser ablation in liquid,Optical thermometry,Upconversion luminescence
更新于2025-09-23 15:21:01
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Dynamic Structural Color from Wrinkled Thin Films
摘要： Structural color caused by thin-film interference is widespread and simple in nature. Many researchers have already showed the reversible color change of structural color system, but it is difficult to regulate dynamically with tunable intensity and viewable angle. Herein, a dynamic structural color platform is reported by combining spontaneous thin film interference and wrinkling phenomenon in nature. This robust yet low cost strategy enables large-scale and spatially arbitrary preparation of a uniform structural color surface through the whole visible spectral range. Furthermore, the prepared isotropic and anisotropic structural colors on disordered and ordered wrinkled thin films (WTFs) exhibit different optical properties that can be precisely and reversibly regulated by ultraviolet (UV) light and near-infrared (NIR) light irradiation. This exquisite and tunable structural color platform may find applications in information storage, smart display, anticounterfeiting and encryption.
关键词： dynamic structural color,tunable viewable angle,thin film,reversible wrinkle
更新于2025-09-23 15:19:57
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Controlling Nucleation Process of InP/ZnS Quantum Dots Using Zeolite as A Nucleation Site
摘要： As a representative of III-V semiconductor materials, InP/ZnS quantum dots are regarded as the star material in the field of light-emitting devices due to their low toxicity and suitable luminescence range. However, there are still some major problems in the preparation process of InP/ZnS QDs, such as phosphine precursors are expensive and difficult to preserve and the nucleation time of short wavelength InP/ZnS QDs is too short and the size distribution is too large. In this paper, we'll replace the traditional tris(trimethylsilyl)phosphine with the tris(diethylamino)phosphine as a cheaper phosphine precursor and propose a novel and convenient method for adjusting the luminescence wavelength of InP/ZnS QDs. Different from the traditional method to adjust the emission wavelength by changing the nucleation time, the emission wavelength of InP/ZnS QDs was regulated by changing the number of initially formed cores. Zeolites do duty for providing a nucleation site for the InP cores. The InP/ZnS QDs emitted from 522 nm to 589 nm were obtained. Moreover, the obtained InP/ZnS QDs has good monochromaticity, the minimum half-width (half-full width) up to 48 nm. This method provides a new way to adjust the size of quantum dots with good performance.
关键词： Zeolites,Indium phosphide,Color tunable,Quantum dots,nucleation site
更新于2025-09-23 15:19:57
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Realizing bright blue-red color-tunable emissions from Gd2GeO5:Bi3+,Eu3+ phosphors through energy transfer toward light-emitting diodes
摘要： Novel Bi3t, Eu3t co-doped Gd2GeO5 (GGO) phosphors were prepared by a high-temperature solid-state reaction method. X-ray diffraction, photoluminescence (PL), CIE chromaticity coordinates, internal quantum efficiency (IQE), and temperature-dependent PL spectra were applied to analyze the as-obtained phosphors. The emission spectra of the GGO:Bi3t, Eu3t phosphors showed both a broad blue band of Bi3t ions emission centered at 453 nm and the characteristic sharp red emission lines of Eu3t ions, corresponding to the 3P1→1S0 allowed transition of the Bi3t ions and the 5D0→7FJ (J ? 0, 1, 2, 3, 4) transitions of the Eu3t ions, respectively. Notably, the as-prepared GGO:Bi3t, Eu3t phosphors exhibited color-tunable emissions from blue (Bi3t) to red (Eu3t) with increasing the Eu3t doping concentration via a high-efficiency energy transfer process. Moreover, the mechanism of energy transfer from Bi3t to Eu3t ions was determined to be the dipole-quadrupole interaction. Impressively, the optimal GGO:0.05Bi3t, 0.12Eu3t phosphors had an outstanding IQE as great as 88% and good thermal stability. All these meaningful results demonstrated that blue-red color-tunable GGO:Bi3t, Eu3t phosphors have potential applications in white light-emitting diodes (LEDs) and plant growth LEDs.
关键词： Gd2GeO5,Energy transfer,Phosphors,Eu3t,Bi3t,Color-tunable emissions
更新于2025-09-23 15:19:57
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Structural micro-modulation on Bi3+ doped Ba2Ga2GeO7 phosphor with considerable tunability of the defect-oriented optical properties
摘要： We report a new Ba2Ga2GeO7:Bi3+ phosphor with broad emission almost covers the entire visible area generated from different bismuth emission centers in crystalline structure. The two peaks positions are invariably located at 497 and 611 nm which were independently excited by 365 and 387 nm excitation sources. As the emission tightly relies on the excitation source in an extremely wide range (260 to 470 nm), the emission color can be easily manipulated from cyan to red. The WLEDs devices with Ra = 90.40 and 91.98 were fabricated by employing Ba2Ga2GeO7:0.012Bi3+ as a red component phosphor. Through analyzing, we found P2 (Ga/Ge) sites tend to form vacancies in the sintering process. When bismuth concentration is set fixed, the luminescent intensity is quite dependent on the quantity of Ga or Ge vacancies which are beneficial to form Bi3+ emission centers and provide a fresh idea for structural micro-modulation. Our results also provide new insights for understanding the roles of the vacancy played in phosphors.
关键词： luminescence,bismuth,color-tunable,WLEDs,phosphor,vacancy
更新于2025-09-19 17:15:36