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Facile Synthesis and Controllable Emission of Tm <sup>3+</sup> /Er <sup>3+</sup> -Doped and -Co-doped α-NaYbF <sub/>4</sub> Upconversion Nanocrystals
摘要： Tm3+, Er3+-doped and -co-doped α-NaYbF4 nanoparticles were synthesized via a facile hydrothermal route with oleic acid as the capping agent. Experimental results showed that the doped NaYbF4 nanoparticles possessed a cubic phase with the average size of ～13 nm. Upon excitation by a 980 nm laser, the as-synthesized nanoparticles exhibited blue and red upconversion emissions corresponding to the monodoped Tm3+, Er3+ in the cubic-phase NaYbF4, respectively, and intense green and red emissions in the Tm3+/Er3+-co-doped NaYbF4 nanoparticles. Furthermore, the possible energy transfer mechanism among Yb3+/Tm3+/Er3+ in α-NaYbF4 nanoparticles was also proposed. The cell toxicity test revealed that the as-synthesized upconversion nanoparticles possessed remarkably low cytotoxicity. All of the advantageous features including facile synthesis, controllable emission, and low cytotoxicity make the upconversion nanoparticles promising for multicolor bioimaging and anti-counterfeiting applications.
关键词： anti-counterfeiting applications,multicolor bioimaging,upconversion nanocrystals,hydrothermal synthesis,energy transfer mechanism,α-NaYbF4,low cytotoxicity,Tm3+/Er3+-doped
更新于2025-09-04 15:30:14
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Er doped layered perovskites with Dual mode luminescent behavior and tunable multicolor upconversion emission
摘要： Er3+ doped BST nanoparticles with Aurivillius layered structure are synthesized through common solid state method. Photoluminescence spectroscopy has shown that these oxides are capable of emitting light under UV (366nm) and IR (980nm) source. The effect of Er3+ to Yb3+ concentration ratio on upconversion emission are investigated and possible upconversion and energy transfer mechanisms are suggested based on the number of photons participating in UC process. Shift in the upconversion emission from green to red region is visualized by CIE chromaticity diagram. The superiority of coexistence of stoke and anti-stoke emission in a single host lattice with a single activator ion, besides to tunability of UC luminescence only by controlling sensitizer/activator ratio are very interesting features which can be used to produce dual mode multicolor luminescent ink with high security level against forgery.
关键词： Aurivillius perovskites,Dual mode luminescent,Security ink,Upconversion
更新于2025-09-04 15:30:14
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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
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Controllable competitive nanocrystallization of La3+-based fluorides in aluminosilicate glasses and optical spectroscopy
摘要： Glass ceramic has been regarded as an alternative to traditional bulk materials such as single crystal and transparent ceramic. The nucleation/growth behavior of glass ceramic via crystallization is an important topic but is seldom studied so far. In the present work, a series of La3+-based oxyfluoride aluminosilicate glasses are designed to understand their nanocrystallization processes upon heating. Impressively, controllable LaF3, α-NaLaF4 and β-NaLaF4 phase-competitive crystallization in glasses is achieved and structural/spectroscopic characterizations confirm the key role of Al/Si ratio to determine the release of Na+ ions from glass network to participate in crystallization and phase transformation. Furthermore, the developed glass ceramics are evidenced to be ideal hosts for lanthanide dopants (such as Eu3+ and Yb3+/Er3+), which can effectively incorporate into the precipitated fluoride crystal lattices by substituting La3+ ions. As a consequence, incoherent LED-excitable upconverting devices are constructed to demonstrate their promising application as emitting media in display.
关键词： Luminescence,Glass ceramics,NaLaF4,Optical materials,Upconversion
更新于2025-09-04 15:30:14
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Resonant Plasmon-Enhanced Upconversion in Monolayers of Core-Shell Nanocrystals: Role of Shell Thickness
摘要： The upconversion luminescence (UCL) of colloidal lanthanide-doped upconversion nanocrystals (UCNCs) can be improved either by precise encapsulation of the surface by optically inert shells around the core, by an alteration of the nearby environment via metal nanoparticles, or by a combination of both. Considering their potential importance in crystalline silicon photovoltaics,the present study investigates both effects for two-dimensional arrangements of UCNCs. Using excitation light of 1500 nm wavelength, we study the variation in the upconversion luminescence from an Er3+-doped NaYF4 core as a function of the thickness of a NaLuF4 shell in colloidal solutions as well as in spin-cast-assisted self-assembled monolayers of UCNCs. The observed UCL yields and decay times of Er3+ ions of the UCNCs increase with increasing shell thickness in both cases, and nearly no variation in decay times is observed in the transition of the UCNCs from solution to film configurations. The luminescence efficiency of the UCNC monolayers is further enhanced by electron-beam-lithographic-designed Au-nanodiscs deposited either on top or buried within of the monolayer. It is observed that the improvement by the nanocrystal shells is greater than that of the Au-nanodiscs.
关键词： shell thickness,core-shell nanocystals,monolayer,upconversion,Plasmon enhancement
更新于2025-09-04 15:30:14
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Dual-Channel Photoelectrochemical Ratiometric Aptasensor with Up-converting Nanocrystals Using Spatial-Resolved Technique on Homemade 3D Printed Device
摘要： A near-infrared light (NIRL)-activated ratiometric photoelectrochemical (PEC) aptasensor was fabricated for detection of carcinoembryonic antigen (CEA) coupling with upconversion nanoparticles (UCNPs)-semiconductor nanocrystals-based spatial-resolved technique on a homemade 3D printing device in which a self-regulating integrated electrode was designed for dual signal readout. The as-prepared NaYF4:Yb, Er UCNPs@CdTe nanocrystals were initially assembled on two adjacent photoelectrodes, then CEA aptamer 1 (A1) and capture DNA (CA) were modified onto two working photoelectrodes (WP1 and WP2) through covalent binding, respectively, and then gold nanoparticle-labeled CEA aptamer 2 (Au NP-A2) were immobilized on the surface of functional WP2 for the formation of double-stranded DNA. Upon target CEA introduction, the various concentrations of CEA were captured on the WP1, whereas the binding of the CEA with Au NP-A2 could be released from the WP2 thanks to the highly affinity of CEA toward A2. The dual signal readout with the 'signal-off' of WP1 and 'signal-on' of WP2 were employed for the spatial-resolved PEC (SR-PEC) strategy to detect CEA as an analytical model. Combining NaYF4:Yb, Er UCNPs@CdTe nanocrystals with spatial-resolved model on 3D printing device, the PEC ratiometric aptasensor based on steric hindrance effect and exciton-plasmon interactions (EPI) exhibited a linear range from 10.0 pg mL-1 to 5.0 ng mL-1 with a limit of detection of 4.8 pg mL-1 under 980 nm illumination. The SR-PEC ratiometric strategy showed acceptable stability and reproducibility with a superior anti-interference ability. This approach can provide the guidance for the design of ratiometric, multiplexed and point-of-care biosensors.
关键词： 3D printing device,upconversion nanoparticles,Photoelectrochemical biosensor,ratiometric,spatial-resolved technique,carcinoembryonic antigen
更新于2025-09-04 15:30:14