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Improved upconversion photoluminescence properties of 0.965K0.4Na0.58Li0.02Nb0.96Sb0.04O3–0.035Bi0.5K0.5ZrO3:0.25%Er/xIn lead-free piezoelectric ceramics with balanced piezoelectric coefficient and Curie temperature
摘要： A series of erbium- and indium-doped 0.965K0.40Na0.58Li0.02Nb0.96Sb0.04O3–0.035Bi0.5K0.5ZrO3:0.25%Er/xIn lead-free piezoelectric ceramics with upconversion photoluminescence (UCPL) properties were prepared by the conventional solid state reaction. A systematical investigation into the effects of In3+ doping on the structural, dielectric, ferroelectric, piezoelectric, and UCPL properties of the ceramics was carried out. The distribution of Er3+-sites could be modified by In3+ doping according to the analysis of UV–Vis-NIR absorption cross-section, resulting in improved piezoelectric and photoluminescence properties of the ceramics. The optimized comprehensive properties are performed by the x = 0.25% samples of which the piezoelectric coefficient d33 ~ 257 pC/N, Curie temperature TC ~ 273 °C, remanent polarization Pr ~ 12.5 μC/cm2, dielectric constant εr ~ 1551, and d33 ~ 257 pC/N which is the supreme piezoelectric coefficient achieved in KNN-based UCPL ceramics as of now. The results demonstrate that erbium and indium co-doped KNN-based ceramics may have potential applications in electro-optical devices.
关键词： Upconversion photoluminescence,Erbium and indium co-doping,Piezoelectric coefficient,Lead-free piezoelectric ceramics,Curie temperature
更新于2025-09-23 15:21:01
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Optical thermometry through infrared excited green upconversion of KLa(MoO4)2:Yb3+/Er3+ Phosphor
摘要： A series of KLa(MoO4)2:Yb3+/Er3+ phosphor was synthesized by a simple hydrothermal method. Under the excitation of 980 nm laser, the phosphor show intense green bands peaked at 525 and 550 nm and a negligible 658 nm red emission (4F9/2→4I15/2), respectively. The optical temperature sensing properties of the phosphor through the fluorescence intensity ratio (FIR) method were discussed by analyzing intensities ratio of 2H11/2 and 4S3/2 emission around the range of 303–423 K. The maximum sensor sensitivity derived from the FIR of the upconversion(UC) green emissions was approximately 0.0105 K-1. This indicates that the phosphor can be used as an excellent material for optical temperature sensing.
关键词： fluorescence intensity ratio,upconversion,optical temperature sensing
更新于2025-09-23 15:21:01
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Amine-functionalized, porous silica-coated NaYF4:Yb/Er upconversion nanophosphors for efficient delivery of doxorubicin and curcumin
摘要： Upconversion nanoparticles (UCNP) with unique multi-photon excitation photo-luminescence properties have been extensively explored as novel contrast agents for low-background biomedical imaging. There is an increasing interest in employing UCNPs as carrier for drug delivery as these offers a unique opportunity to combine therapy and diagnostics in one platform (theranostics). In the present work, we report microwave-assisted synthesis of hexagonal NaYF4:Yb/Er UCNPs coated with porous silica and functionalized with amine (UCNP@mSiO2). The UCNP@mSiO2 were investigated for controlled delivery of a chemotherapeutic agent, doxorubicin (DOX, hydrophilic), and a chemosensitizing agent, curcumin (CCM, hydrophobic). The drug loading was relatively higher for DOX (17.4%), in comparison to CCM (8.1%). The cumulative drug release from DOX-loaded UCNP@mSiO2 were 30 and 41% at physiological (7.4) and tumoral (6.4) pH, following a pseudo Fickian release pattern, whereas the release from CCM-loaded UCNP@mSiO2 were 27 and 50% at pH 7.4 and 6.4, following a non-Fickian and pseudo-Fickian release patterns. Both DOX and CCM-loaded UCNP@mSiO2 exhibited pH-dependent controlled drug delivery but the effect was more pronounced for CCM, the hydrophobic chemosensitizer. Cell viability assay using HeLa cells showed that DOX-loaded UCNP@mSiO2 inhibit cell growth in a dose-dependent manner, similar to free DOX, but the cell inhibition activity of free CCM was lower than CCM passively entrapped in UCNP@mSiO2. Confocal microscopy studies revealed cell uptake of both the drug by HeLa cells. Thus, UCNP@mSiO2 exhibited the unique capability to deliver hydrophilic and hydrophobic drugs, individually. UCNP@mSiO2 carrier, equipped with theranostic capabilities, may potentially be used for pH-responsive release of chemotherapeutic agents in cancer environment.
关键词： curcumin,porous silica,doxorubicin,drug delivery,Upconversion nanoparticles
更新于2025-09-23 15:21:01
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Organic Upconversion Display with an over 100% Photon-to-photon Upconversion Efficiency and a Simple Pixelless Device Structure
摘要： Comparing to traditional near infrared (NIR) imaging devices, NIR-to-visible upconversion display which integrated a NIR photodetector with a visible light-emitting diode have merits of simple device structure, low cost, high resolution, and a simple pixelless structure. However, photon-to-photon upconversion efficiencies of these devices are typically much lower than unity. Here we report an all-organic NIR-to-visible upconversion display with a photon-to-photon upconversion efficiency higher than 100% by integrating a photomultiplying organic NIR photodetector with a high-efficiency thermally activated delayed fluorescent organic light-emitting-diode. To the best of our knowledge, this is the first report showing a photon-to-photon upconversion efficiency over 100% without using a built-in transistor for current amplification.
关键词： organic photodetector,NIR-to-visible upconversion,photon-to-photon efficiency,thermally activated delayed fluorescence,organic light-emitting diode
更新于2025-09-23 15:21:01
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High-power operation of double-pass pumped Nd:YVO <sub/>4</sub> thin disk laser
摘要： A simple, compact, double-pass pumped Nd:YVO4 thin disk laser is demonstrated. Its continuous-wave performance with different Nd doping concentrations and thicknesses is investigated experimentally. The maximum output power of 17.7 W is achieved by employing a 0.5 at.% doped sample, corresponding to an optical-to-optical ef?ciency of 46% with respect to the absorbed pump power. In addition, a numerical analysis and an experimental study of the temperature distribution, and thermal lens effect of the Nd:YVO4 thin disk, are presented considering the in?uence of the energy transfer upconversion effect and the temperature dependence of the thermal conductivity tensor. The simulated results are in good agreement with the experimental results.
关键词： energy transfer upconversion effect,Nd:YVO4,thin disk laser,thermal lens effect
更新于2025-09-23 15:19:57
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Boosted thermometric performance in NaGdF4:Er3+/Yb3+ upconverting nanorods by Fe3+ ions doping for contactless nanothermometer based on thermally and non-thermally coupled levels
摘要： Series of Er3t/Yb3t/Fe3t-tridoped NaGdF4 nanorods with eminent upconversion (UC) emission performance were obtained at room temperature. The effect of Fe3t ion content on the phase structure, morphology, thermal stability and luminescent behaviors of the resultant samples was systematically studied. Upon 980 nm light irradiation, dazzling green and red UC emissions originating from Er3t ions were gained and their emission intensities were sharply improved with adding the Fe3t ions. The relevant UC mechanism was verified to be the two-photon absorption process. Furthermore, through analyzing the responses of the emissions originating from the thermally (i.e., 2H11/2, 4S3/2) and non-thermally (i.e., 4F9/2, 4S3/2) coupled levels to temperature, the thermometric performance of the designed nanorods was investigated. Compared with those of the thermally coupled levels, the thermometric properties of the synthesized nanorods were significantly enhanced when the non-thermally coupled levels were employed. The maximum absolute and relative sensor sensitivities of the NaGdF4:Er3t/Yb3t/0.005Fe3t nanorods were 0.0191 K-1 and 0.567% K-1, respectively, which were higher than those of the NaGdF4:Er3t/Yb3t nanorods. Ultimately, the internal heating performance of the final products induced by the laser pump power was also explored. These results revealed that the Er3t/Yb3t/Fe3t-tridoped NaGdF4 nanorods were potential upconverting compounds for ratiometeric nanothermometers and optical heaters.
关键词： Thermometers,Upconversion,Fluorides,Luminescence,Nanoparticles
更新于2025-09-23 15:19:57
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Controlled synthesis and upconversion luminescence properties of Yb3+/Er3+ co-doped Bi2O3 nanospheres for optical and X-ray computed tomography imaging
摘要： Bi2O3 nanospheres co-doped with Yb3t/Er3t upconverting ions pair have been successfully synthesized via a facile hydrothermal method followed by a heat treatment. The resulting Bi2O3:Yb3t,Er3t nanospheres show a monodisperse spherical morphology with narrow size distribution (~180 nm) and display intense upconversion luminescence under 980 nm laser excitation. It is found that the crystal structure, morphology and upconversion luminescence properties of nanospheres have a direct relationship with the doping concentration of Yb3t and the subsequent calcination temperature. These Bi2O3:Yb3t,Er3t nanospheres can be prepared in large quantities and can be easily modified with a layer of biocompatible polyethyleneimine (PEI) molecules. The yielded nanospheres could not only maintain uniform size and morphological characteristics, but also show good water dispersibility and biocompatibility. Remarkably, these Bi2O3:Yb3t,Er3t upconversion nanophosphors could also act as an effective contrast agent for X-ray computed tomography (CT) imaging, which show higher contrast efficacy than commercial iodine-based contrast agent. The proposed facile synthetic route and inexpensive matrix materials pave the way for broad use of these Bi2O3:Yb3t,Er3t nanospheres as ideal dual-mode bio-imaging probes in biomedical field.
关键词： Hydrothermal synthesis,CT imaging,Bi2O3,Upconversion luminescence,Nanophosphors
更新于2025-09-23 15:19:57
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Lanthanide-based Nanocomposites for Photothermal Therapy under Near Infrared Laser: Relationship between Light and Heat, Bio-stability and Reaction Temperature
摘要： In this research, typical organic/inorganic photothermal therapy (PTT) agents were designed with combination of up-conversion luminescent (UCL) or NIR II imaging rare earth nanomaterials for photoacoustic (PA)/UCL/NIR II imaging-guided PTT under NIR laser irradiation. The results show that: (1) PTT effect mainly comes from NIR absorption and partly from the UCL light conversion. (2) The visible UCL emission is mainly quenched by the NIR absorption of the coated PTT agent and partly quenched by the visible absorption, indicating the excitation may play a more important role than in the UCL emission process. (3) The bio-stability of the composite might be decided by the synthesized reaction temperature. Among the five inorganic/organic nanocomposite, UCNP@MnO2 is the most suitable candidate for cancer diagnosis and treatment due to its stimuli-response ability to the micro-acid environment of tumor cells and highest bio-stability. The composites generate heat for PTT after entering the tumour cells, and then the visible light emission gradually regains as MnO2 is reduced to colorless Mn2+ ions, thereby illuminating the cancer cells after the therapy.
关键词： Photothermal therapy,Upconversion luminescence imaging,Mito-tracker,Photoacoustic imaging,Inorganic/organic nanocomposite
更新于2025-09-23 15:19:57
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Neara??Infrareda??toa??Visible Photon Upconversion by Introducing an Sa??T Absorption Sensitizer into a Metala??Organic Framework
摘要： Triplet-triplet annihilation-based photon upconversion (TTA-UC) of near-infrared (NIR) light to visible light in the solid-state remains as a great challenge due to the sensitizer aggregation that impedes the efficient triplet energy transfer. Herein, we successfully introduce a molecular sensitizer exhibiting direct singlet-to-triplet (S–T) absorption into a new emitter-based metal-organic framework (MOF) to achieve an efficient triplet sensitization and a NIR-to-visible TTA-UC in the solid-state.
关键词： photon upconversion,near-infrared light,metal-organic framework,singlet-to-triplet absorption,triplet-triplet annihilation
更新于2025-09-23 15:19:57
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Upconverting carbon quantum dots: An eco-friendly material for light energy harvesting and bio-imaging
摘要： Eco-friendly carbon quantum dots (CQDs) are finding many applications in the field of chemical sensing, photocatalytic applications, photovoltaic applications, bio-imaging, etc. Herein, CQDs are grown via a cost-effective manner, where the lemon and onion extracts are used as the reaction precursors. Formed CQDs are characterized using electronic spectroscopic and microscopic techniques. The emission yield of the present CQDs is found to be 11.2%. In contrast to general fluorophores/ semiconductors, this material showed an upconverting photoluminescence. Upon exciting with a lower energy continuous wave light of 695 nm, we observed an upconverted emission centered at 438 nm. For upconversion, as the excitation wavelength is at the lower energy, the photodecomposition of the material will be minimum. This will increase the efficiency and the lifetime of the light harvesting devices as the photodecomposition is minimum at lower wavelengths. Also, upconverting CQDs can be a potential candidate for the bio-imaging applications as the light induced decomposition of the biological samples will be minimum.
关键词： Eco-friendly material,Carbon quantum dots,Light harvesting applications,Upconversion
更新于2025-09-23 15:19:57