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Tunable Emission of Bluish Zn-Cu-Ga-S Quantum Dots by Mn Doping and their Electroluminescence
摘要： Based on bluish-emitting double-shelled quantum dots (QDs) of Zn?Cu?Ga?S (ZCGS)/ZnS/ZnS, Mn doping into ZCGS host with different Mn/Cu concentrations is implemented via surface adsorption and lattice diffusion. The resulting double-shelled Mn-doped ZCGS (ZCGS:Mn) QDs exhibit a distinct Mn2+ 4T1?6A1 emission as a consequence of effective lattice incorporation simultaneously with host intragap states-involving emissions of free-to-bound and donor-acceptor pair (DAP) recombinations. The relative contribution of Mn emission in the overall photoluminescence (PL) is consistently proportional to its concentration, resulting in tunable PL from bluish, white, to reddish white. Regardless of Mn doping and its concentration all QDs possess high PL quantum yield (QY) levels of 74?79%. Those undoped and doped QDs are then employed as an emitting layer (EML) of all-solution-processed QD-light-emitting diodes (QLEDs) with hybrid charge transport layers and their electroluminescence (EL) is compared. When compared to undoped QDs, doped analogues give rise to a huge spectral disparity of EL versus PL, specifically showing a near-complete quenching of Mn2+ EL. This unexpected observation is rationalized primarily by considering unbalanced carrier injection to QD EML on the basis of energetic alignment of the present QLED and rapid trapping of holes injected at intragap states of QDs.
关键词： Tunable emission,Electroluminescence,Emission quenching,Zn?Cu?Ga?S quantum dots,Mn doping
更新于2025-11-20 15:33:11
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Saponification Precipitation Method of CsPbBr3 Nanocrystals with Blue-Green Tunable Emission
摘要： We report on a new synthesis process for halide perovskite nanoplatelets and nanoplates that switches the production process of the cesium precursor from a fatty acid/cesium salt reaction to a cesium base/fatty acid ester reaction, thus enabling the reaction to occur in ambient conditions in minutes instead of hours. The saponification precipitation process reported here, as a result, does not require a vacuum oven or inert reaction environment in obtaining the cesium precursor, or any part of the reaction. Furthermore, the process creates a hygroscopic byproduct that results in a self-drying synthesis. The obtained perovskite nanocrystals exhibit a blue-green tunable emission that occurs via quantum confinement effect, phase, and morphology change. The consequence of these physical processes is that the band gap is highly tunable with temperature and the resulting nanocrystals show remarkable optical properties, while greatly simplifying the production of halide perovskite nanoplatelets and nanoplates.
关键词： Blue-Green Tunable Emission,Saponification Precipitation Method,Hybrid Materials,Magnetic,CsPbBr3 Nanocrystals,Plasmonics,Optical
更新于2025-11-19 16:46:39
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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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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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Tunable emission of cadmium-free transition metal (Cu, Mn, Ag) co-doped ZnInS/ZnS core-shell quantum dots
摘要： Color tunable quantum dots (QDs) based on the Cu, Mn, Ag co-doped ZnInS core and ZnS outer-shell were synthesized by using an eco-friendly method. Core-shell doped QDs with the average size of 3.85 nm were obtained by using a one-pot synthesis followed by a hot injection with n-dodecanethiol (DDT) and oleylamine (OLA) as stabilizers in oil phase. Cu, Mn and Ag ions were introduced as single-dopant or co-dopants during the synthesis, providing an effective means to control the emission color of the QDs. The as-synthesized QDs showed photoluminescence emission ranging from green (530 nm) to near-red (613 nm), adjusted by doping components, dopant concentration, and Zn/In ratio. Importantly, quasi-white emission has been achieved by controlling the concentration of co-doped metal ions (Mn, Cu and Ag). The primary results demonstrated the promising potential of co-doped QDs as alternative materials for future high quality white LED applications.
关键词： doping,tunable emission,white light,core-shell,zinc group quantum dots
更新于2025-09-19 17:13:59
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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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Tunable emission of LiCa3MgV3O12:Bi3+ via energy transfer and changing excitation wavelength
摘要： LiCa3MgV3O12:Bi3+ phosphor is successfully synthesized by the high-temperature solid-state reaction method in air. The crystal structures and luminescence properties are investigated. Excitation/emission bands of LiCa3MgV3O12:Bi3+ phosphor show red-shift with increasing the monitored/excitation wavelengths from short to long. The doping of Bi3+ ion can result in the host LiCa3MgV3O12 lattice distortion and the energy transfer to Bi3+. The tunable emission of LiCa3MgV3O12:Bi3+ phosphor from blue-green to yellow can be observed with increasing Bi3+ concentration from 0 to 8 mol%. The chromaticity coordinates of LiCa(3-x)MgV3O12:xBi3+ phosphors can change from (0.2393, 0.3260) to (0.4358, 0.4472) with increasing Bi3+ concentration from 0 to 8 mol%. The existence of VO4 3? → Bi3+ ET in LiCa3MgV3O12:Bi3+ phosphor is indicated by the luminescence properties. The luminous mechanism of LiCa3MgV3O12:Bi3+ phosphor is explained by the con?gurational coordinate diagrams of VO4 3? and Bi3+. The experimental results are helpful for the luminescence property researches of other Bi3+-doped luminescence materials.
关键词： Energy transfer,Tunable emission,LiCa3MgV3O12: Bi3+ ions,Vanadates
更新于2025-09-10 09:29:36
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Design and energy transfer mechanism for single-phased Gd2MgTiO6: Bi3+, Eu3+ tunable white light-emitting phosphors
摘要： In recent years, numerous efforts have been made to develop single-phased white light-emitting phosphors for the near-UV region to solve problems of color reabsorption and ratio regulation between different phosphors. In this work, we have designed Bi3+- and Eu3+-codoped single-phased Gd2MgTiO6 phosphors to achieve tunable white light emission based on multi-luminescence center energy transfer. The structural analysis showed that all the samples were crystallized as a monoclinic double perovskite with the P21/n symmetry space group (No. 14), with HRTEM images showing clear lattice fringes between the lattice planes. The single Bi3+-doped Gd2MgTiO6 sample exhibits two obvious emission peaks at 417 and 508 nm, which correspond to a characteristic 3P1 → 1S0 transition for the Bi3+ ions under near-UV excitation due to two types of Bi3+ emission centers, with their relative emission intensity depending closely on the value of the excitation wavelength. In this case, a suitable choice of excitation wavelength can achieve tunable emission for Gd2MgTiO6: Bi3+ between blue and green. Eu3+ is codoped into Gd2MgTiO6 as a red emission component and shows sharp emission lines that correspond to the characteristic 5D0 → 7FJ (J = 1, 2, 3, and 4) transitions of Eu3+ ions. Energy transfer in Gd2MgTiO6: Bi3+, Eu3+ has been confirmed by the electric dipole–dipole (d–d) interaction from Bi3+ to Eu3+. Our experiments show that it is straightforward to create tunable white light emission by adjusting the excitation scheme and Eu3+ concentration. Moreover, a schematic for the energy transfer mechanism and simplified spectral levels based on Bi3+ and Eu3+ ions has also been established.
关键词： Eu3+,Bi3+,Gd2MgTiO6,white light-emitting phosphors,energy transfer,tunable emission,near-UV
更新于2025-09-04 15:30:14
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Color-tunable lanthanide metal–organic framework gels
摘要： Fluorescence signi?cantly improves the performance of gels. Various strategies, such as embedment and crosslinking, have been used to integrate extrinsic luminophores into gel systems, but the procedures are usually complex. Herein, for the ?rst time, we report gels with intrinsic and tunable emission color prepared with 5-boronoisophthalic acid (5-bop) and Eu3+, Tb3+, and/or Dy3+ similar to the procedure for the preparation of metal–organic frameworks (MOFs). The single-metal gels exhibit intrinsic trichromatic ?uorescence, due to which full-color emissions are readily obtained by tuning the type and/or ratio of Ln3+ ions to prepare mixed-metal gels. The emission is governed by an antenna e?ect and is thus excited with single-wavelength at 275 nm. The nucleation-growth mechanism reveals that the Ln3+ ions and 5-bop produce separated layers, which then grow anisotropically to form nanoribbons by high coordinated valence of Ln3+ ions and biased carboxyl distribution as well as steric hindrance and hydrogen bonds of the boric acid group in 5-bop. The nanoribbons entangle together to generate chemical-physical hybrid gels. To the best of our knowledge, this is the ?rst example of gels with inherent and tunable emission color. Due to their optical and viscoelastic properties, the gels have numerous potential applications such as tunable emission and multi-target detection.
关键词： metal–organic frameworks,lanthanide,gels,tunable emission,Fluorescence
更新于2025-09-04 15:30:14