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Ultrathin, Core–Shell Structured SiO <sub/>2</sub> Coated Mn <sup>2+</sup> ‐Doped Perovskite Quantum Dots for Bright White Light‐Emitting Diodes
摘要： All-inorganic semiconductor perovskite quantum dots (QDs) with outstanding optoelectronic properties have already been extensively investigated and implemented in various applications. However, great challenges exist for the fabrication of nanodevices including toxicity, fast anion-exchange reactions, and unsatisfactory stability. Here, the ultrathin, core–shell structured SiO2 coated Mn2+ doped CsPbX3 (X = Br, Cl) QDs are prepared via one facile reverse microemulsion method at room temperature. By incorporation of a multibranched capping ligand of trioctylphosphine oxide, it is found that the breakage of the CsPbMnX3 core QDs contributed from the hydrolysis of silane could be effectively blocked. The thickness of silica shell can be well-controlled within 2 nm, which gives the CsPbMnX3@SiO2 QDs a high quantum yield of 50.5% and improves thermostability and water resistance. Moreover, the mixture of CsPbBr3 QDs with green emission and CsPbMnX3@SiO2 QDs with yellow emission presents no ion exchange effect and provides white light emission. As a result, a white light-emitting diode (LED) is successfully prepared by the combination of a blue on-chip LED device and the above perovskite mixture. The as-prepared white LED displays a high luminous efficiency of 68.4 lm W?1 and a high color-rendering index of Ra = 91, demonstrating their broad future applications in solid-state lighting fields.
关键词： quantum dots,white light-emitting diodes,core–shells,Mn2+-doping,SiO2-coating
更新于2025-11-14 15:32:45
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Tricolor- and White Light–Emitting Ce <sup>3+</sup> /Tb <sup>3+</sup> /Mn <sup>2+</sup> -Coactivated Li <sub/>2</sub> Ca <sub/>4</sub> Si <sub/>4</sub> O <sub/>13</sub> Phosphor via Energy Transfer
摘要： Single-component tunable Li2Ca4Si4O13:Ce3+,Tb3+,Mn2+ phosphors were successfully synthesized at 950 °C. Li2Ca4Si4O13:Ce3+,Tb3+ exhibits two luminescence peaking at 430 and 550 nm, which originated from the allowed 5d → 4f transition of the Ce3+ ion and the 5D4 → 7FJ (J = 6, 5, 4, 3) transition of the Tb3+ ion, respectively. Moreover, by codoping Ce3+ ions in the Li2Ca4Si4O13:Mn2+ system, yellow-red emission from the forbidden transition of Mn2+ could be enhanced. Under UV excitation, dual energy transfers (ETs), namely, Ce3+ → Mn2+ and Ce3+ → Tb3+, are present in the Li2Ca4Si4O13:Ce3+,Tb3+,Mn2+ system. The ET process was confirmed by the overlap of the excitation spectra, variations in the emission spectra, ET efficiency, and decay times of phosphors. In addition, quantum yields and CIE chromatic coordinates are presented. The emission color of these phosphors can be tuned precisely from blue to green via ET of Ce3+ → Tb3+ and from blue to yellow via ET of Ce3+ → Mn2+. White light can also be achieved upon excitation of UV light by properly tuning the relative composition of Tb3+/Mn2+. This result indicates that the developed phosphor may be regarded as a good tunable emitting phosphor for UV light-emitting diodes.
关键词： phosphor,energy transfer,Mn2+,Tb3+,Li2Ca4Si4O13,Ce3+,white light-emitting diodes
更新于2025-11-14 15:29:11
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Narrow-Band Green-Emitting Sr <sub/>2</sub> MgAl <sub/>22</sub> O <sub/>36</sub> :Mn <sup>2+</sup> Phosphors with Superior Thermal Stability and Wide Color Gamut for Backlighting Display Applications
摘要： The narrow-band emitting phosphors have been extensively investigated in recent years, with the expectation that a wide color gamut of phosphor-converted backlighting device could be fabricated. Due to the weak electric–phonon interaction and low structural relaxation caused by the high rigid crystal structure and symmetric coordination environment, Sr2MgAl22O36:Mn2+ (SMAO:Mn2+) shows a narrow full-width at half-maximum of 26 nm, a high color purity of 81.5%, and a low thermal quenching (82% at 473 K of the initial intensity at 298 K). Using K2SiF6:Mn4+ as the red phosphor, SMAO:Mn2+ as the green one, and GaN-based chip as the blue component, the white light-emitting diode exhibits a National Television Standard Committee value of 127%. All the results demonstrate that the SMAO:Mn2+ phosphor has a promising application in the field of advanced wide-color-gamut backlight display, and the establishment of the relationships between the narrow-band emission and crystal structure can also be applied to design other novel narrow-band phosphors for backlighting technologies.
关键词： color gamut,inorganic phosphors,narrow-band emission,white light-emitting diodes,Sr2MgAl22O36:Mn2+,thermal stability,backlight displays
更新于2025-09-23 15:23:52
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Ultra-small two dimensional MXene nanosheets for selective and sensitive fluorescence detection of Ag+ and Mn2+ ions
摘要： The present work offers a new exploration for the selective sensing of metal ions (Ag+ and Mn2+) via fluorescence quenching of Ti3C2 MXene nanosheets (NSs). Monolayer MXene Ti3C2 NSs exhibited excellent ability to sense Ag+ and Mn2+ ions because of their good hydrophilicity and distinctive surface functionality. The as-synthesised Ti3C2 NSs exhibited highest emission fluorescence peak at 461 nm upon the excitation wavelength of 384 nm. The fluorescence emission peak of Ti3C2 NSs was remarkably quenched only upon the addition of Ag+ and Mn2+ ions, exhibiting good linear response between I0/I and concentration in the range of 0.1–40 μM and 0.5–60 μM for Ag+ and Mn2+ ions. The proposed sensor shows lower detection limits of 9.7 and 102 nM for Ag+ and Mn2+ ions with good selectivity. Additionally, the method is effectively applied to detect Ag+ and Mn2+ ions in food and real water samples with excellent recoveries.
关键词： FT-IR,MXene nanosheets,Florescence and UV–vis spectroscopic techniques,Ag+ and Mn2+ ions
更新于2025-09-23 15:23:52
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Effects of composition modulation on the structural and luminescence properties of Mn2+ doped Na2Mg1-xCaxSiO4 green-emitting phosphors
摘要： On the basis of the crystalline structural information that the matrix material has excellent physical-chemical stabilization, green-emitting Na2(Mg1-xCax)SiO4:Mn2+ (NMCS:Mn2+) phosphors were synthesized by a traditional solid-state method and systematically optimized, and their photoluminescence properties were studied. The luminescence properties of NMCS:Mn2+ phosphors as a function of Ca2+ concentrations were investigated. The structure of the as-prepared phosphors was identified by the X-ray diffraction (XRD) and the luminescent properties were characterized by the luminescence spectra, decay curve and CIE chromaticity coordinates. The emission peaks at 520nm generated by 4T1(4G)→6A1(6S) transition of the Mn2+ doped NMCS phosphors can provide a green component in the tri-color system. The emission intensity would be enhanced greatly by Ca2+-substitution and it can be observed that these emission peaks would shift to shorter wavelengths (blue-shift) with the increasing of Ca2+ content. The large enhancement of emission intensity and the shift of emission peaks due to Ca2+ substitution may provide a reference in the research of new type and more efficient phosphors for NUV-LEDs.
关键词： green phosphor,luminescence properties,Na2(Mg1-xCax)SiO4:Mn2+
更新于2025-09-23 15:21:21
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Photoluminescence and phosphorescence of Mn2+ ion activated green phosphor Na2ZnSiO4:Mn2+ synthesized by self-reduction
摘要： Mn2+ activated phosphors are vital for lighting and displays, whereas the multivalent states characteristics of Mn made that reducing atmosphere (such as H2, CO, H2/N2) is generally required in the synthesis processes. Herein, a Mn2+ doped silicate green phosphor Na2ZnSiO4:Mn2+ was synthesized by an unconventional self-reduction of Mn7+/Mn4+/Mn3+ to Mn2+ under air atmosphere. Upon 260 nm excitation, an intense green photoluminescence band centered at 515 nm and the phosphorescence after stoppage of the excitation source can be observed in this phosphor. The photoluminescence and phosphorescence properties, self-reduction processes and mechanism in Na2ZnSiO4:Mn, as well as the phase transformations of the different Mn sources (MnCO3, Mn2O3, MnO2) at various temperatures were investigated systematically. Based on these investigations, together with the density functional theory (DFT) calculations, a self-reduction mechanism of Mn7+/Mn4+/Mn3+ to Mn2+ based on zinc vacancies VZn'' has been proposed. This work provides not only a new luminescent material, but also new insights into the Mn valence states controlling and luminescence tuning.
关键词： Mn2+,redox reactions,self-reduction,defects
更新于2025-09-19 17:15:36
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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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Neoteric Mn <sup>2+</sup> ‐activated Cs <sub/>3</sub> Cu <sub/>2</sub> I <sub/>5</sub> dazzling yellow‐emitting phosphors for white‐LED
摘要： Neoteric Mn2+‐activated Cs3Cu2I5 yellow‐emitting halides were achieved by the simple solid‐state reaction route. The near‐ultraviolet light was the suitable excitation lighting source for the resultant halides. The resultant halides exhibited bright yellow emission under the excitation of 378 nm and the optimum dopant content was 11 mol%. The multipole‐multipole interaction contributed to the concentration quenching mechanism and the critical distance was 28.65 ?. The thermal resistance of the prepared compounds was identified by the temperature‐dependent emission spectra. Ultimately, the designed light‐emitting diode showed bright white light with satisfied color rendering index, proper color coordinate, and suitable correlated color temperature. These results indicated that the prepared yellow‐emitting halides were suitable for indoor illumination.
关键词： white‐LED,phosphors,Mn2+ ions,luminescence
更新于2025-09-19 17:13:59
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Facile synthesis of manganese (II)-doped ZnSe nanocrystals with controlled dimensionality
摘要： Doping is one of the key technologies in modern semiconductor science and industry. However, the synthetic control of doped nanocrystals is difficult to achieve. Here, we report the facile synthesis of manganese (II) doped ZnSe nanocrystals with controlled dimensionality. A strong Lewis acid-base reaction using air-stable and environmentally friendly metal chlorides as precursors can readily produce a large amount of quantum-confined ZnSe:Mn2+ nanocrystals. A combination of primary and secondary amines is used to control the synthetic chemistry, which enables the shape of the doped nanocrystals to be controlled. The final doping concentration of the products can be finely tunable, which is critical for carrier relaxation dynamics. It turns out that the threshold doping level for the maximum photoluminescence intensity of doped nanocrystals highly depends on their shape. Furthermore, this simple synthetic method is extendable to obtain various Mn2+-doped II–VI semiconductor nanocrystals such as CdS:Mn2+ and ZnS:Mn2+. Our study will facilitate the fundamental understanding of the doped semiconductor nanocrystals with different shapes, which is potentially useful for a wide range of applications such as lighting, photocatalysis, and bioimaging.
关键词： doping,quantum dots,ZnSe,nanocrystals,photoluminescence,Mn2+
更新于2025-09-12 10:27:22
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Superior fluorescence and high stability of B-Si-Zn glasses based on Mn-doped CsPbBrxI3-x nanocrystals
摘要： CsPbX3 perovskite nanocrystals (NCs) are still limited in their use due to their extreme instability in the air as they will deteriorate in a few days, and their thermal stability is not optimistic. In this study, the red CsPbBrxI3-x (X=1.5, 1.0, 0.8, 0.5, 0.35, 0) NCs and Mn-doped CsPbBrxI3-x NC in zinc borosilicate (B2O3-SiO2-ZnO) glass with cubic perovskite crystal structure were successfully synthesized through melt-quenching and heat-treatment method, which exhibited strong red emission in region of 572 nm ~ 708 nm under 365 nm excitation. Additionally they are stable in the air for several months while showing excellent thermal stability. It is worth mentioning that Mn-doped CsPbBrxI3-x NC glasses are brighter than CsPbBrxI3-x NC glasses under UV light. Because Mn-doped CsPbBrxI3-x NC glasses have good thermal and air stability, they can be used as a red fluorescent material. We fabricated glass with Y3Al5O12:Ce3+ (YAG:Ce3+) phosphor-in-glass (PiG) realized the chromaticity tuning for YAG:Ce3+ phosphor with white light-emitting-diodes (WLED).
关键词： Narrowband emission,Mn2+-Doped CsPbBrxI3-x NC glasses,High stability,High luminescent intensity
更新于2025-09-10 09:29:36