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Currently, upconversion nanocrystals and long-lasting phosphorescent particles have attracted extensive research interest for their possible applications as bioimaging probes. However, there are few reports concerning the achievement of both upconversion luminescence of lanthanide ions and long-lasting phosphorescence of transition metal ions in a sole host so far. Herein, we demonstrate a novel calcium gallium germanium garnet (Ca3Ga2Ge3O12) host where lanthanide ions such as Tm3+/Yb3+ and transition metal ions such as Cr3+ can be easily incorporated through substituting the Ca2+ and Ga3+ respectively. This Cr/Yb/Tm:Ca3Ga2Ge3O12 phosphor exhibits both broadband near-infrared long-lasting phosphorescence of Cr3+ with an afterglow time of more than 7000 s and near-infrared to near-infrared upconversion luminescence of Tm3+. Impressively, it is evidenced that the addition of Yb3+/Tm3+ into Cr:Ca3Ga2Ge3O12 not only results in Tm3+ upconversion luminescence but also greatly increases Cr3+ afterglow time. Based on excitation/emission, three-dimensional thermoluminescence, and time-resolved luminescence spectra, the related long-lasting phosphorescence and upconversion luminescent mechanisms are systematically discussed as well [ABSTRACT FROM AUTHOR]

The purpose of the present work is to demonstrate that the hexagonal Yb/Er:NaGdF4 core size has a great impact on the completeness of the NaYF4 shell covering the core. With the increase of core size, the morphology of core-shell nanocrystals evolves from nanosphere to hexagonal nanoprism and finally to hexagonal nanoplate and, impressively, compared to that on the lateral faces of cores, the shell thickness on the top/bottom faces of cores becomes thinner. The shell growth mechanism is proposed to be the separate nucleation of the shell precursors followed by their ripening-mediated deposition on the cores. Based on this mechanism, controlling the thickness and completeness of the shell on the core can be easily realized by adopting appropriate size cores, which results in the intensification of upconversion luminescence of core-shell nanocrystals 10000 times as high as that of the core-only ones. Generally, these new findings should be beneficial for designing and fabricating complex core-shell architecture and the understanding of structure-related properties of core-shell nanocrystals [ABSTRACT FROM AUTHOR]

A series of Er3+-doped (1 - x/CaF2-xYbF3 (0 ⩽ x ⩽ 0:6) disordered solid-solution nanocrystals with various mean sizes were successfully prepared by a facile solvothermal route. Interestingly, abnormal size-dependent upconversion emissions were demonstrated in these nanocrystals for the first time. With increasing grain size, an obvious enhancement of red to green emission ratio was observed in the Er3+ (2 mol%): 0:4CaF2-0:6YbF3 nanocrystals, which is the opposite of the routine size-dependent upconversion emission behavior reported previously. Taking Eu3+ ions as a structural probe, we investigated the influence of a disordered solid-solution structure on Ln3+ luminescence, and proposed that Ln3+ clusters formed in the host should play a key role to induce this unusual size-dependent upconversion emission phenomenon. As a consequence, multi-colors such as green, yellow, and red upconversion emissions can be easily realized by appropriately modifying the Yb3+ content in the Er3+-doped (1 - x)CaF2-xYbF3 nanocrystals. The reported results will deepen the understanding of size effects on the lanthanide upconversion in nanocrystals. [ABSTRACT FROM AUTHOR]

Novel NaYb1−xGdxF4(0 ≤ x≤ 1) nanocrystals were synthesized by a modified liquid–solid–solution solvothermal route for the first time. X-ray diffraction analyses and transmission electron microscope observations evidenced that the phase, size and shape of NaYb1−xGdxF4nanocrystals were closely related to the Gd3+content. Particularly, when the Gd3+content reached 60 mol%, the final products were highly uniform and monodisperse hexagonal NaYb0.4Gd0.6F4nanorods. By doping appropriate lanthanide activators, these nanorods exhibited efficient dual-sensitizing multicolor emissions, i.e., Gd3+sensitizing down-conversion by an ultraviolet light excitation orYb3+sensitizing up-conversion by a near-infrared one. The lanthanide activator doped NaYb0.4Gd0.6F4nanorods with tunable up-conversion luminescence and proper paramagnetism originating from Gd3+ions may find potential applications in bio-probes and magnetic resonance imaging. [ABSTRACT FROM AUTHOR]

Rare earth ions-doped transparent glass ceramics containing hexagonal GdF3 nanocrystals with a mean size of 16 nm were prepared. Energy dispersive x-ray spectroscopy and luminescence spectrum investigation evidenced the incorporation of rare earth ions into GdF3 nanocrystals. The efficient energy transfer from Gd3+ to Tb3+ was demonstrated in the Tb3+-doped glass ceramics, which resulted in an intense green light emission originated from Tb3+: 5D4 → 7F6 transition via the sensitization of Gd3+. Compared with the precursor glass, the Dy3+-doped glass ceramic exhibited longer lifetime and lower yellow-to-blue emission intensity ratio owing to the allocation of Dy3+ ions in the low-phonon-energy GdF3 environment. Under ultraviolet excitation, the Dy3+-doped samples emitted bright white light, indicating their potential application in white light emitting diodes. [ABSTRACT FROM AUTHOR]

A systematic synthesis of homogeneously distributed lanthanide trifluoride (from LaF3to LuF3) nanocrystals in the same aluminosilicate glass matrix was reported. These fluorides exhibit dimorphism, i.e., the hexagonal structure for those from LaF3to GdF3and the orthorhombic one for those from TbF3to LuF3(including YF3). The Eu3+emission spectra evidenced the partition of the doped rare earth ions into the LnF3nanocrystals, and as an example, the intense ultraviolet upconversion emissions were achieved in the Tm3+ : YbF3nanocrystals containing composite due to the low-photon-energy environment of rare earth ions. These nano-composites may find potential applications in solid-state lasers, 3D displays, amplifiers and other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Transparent 45SiO2—25Al2O3—5CaO—10NaF15CaF2 glass ceramics doped with different levels of Er3+ were prepared. The spherical CaF2 nanocrystals with 10–20nm in size were verified to be homogeneously embedded among the glassy matrix. Room temperature absorption and emission spectra corresponding to 4I13/2↔4I15/2 transitions of Er3+ ions in precursor glasses and glass ceramics, respectively had been measured. For glass ceramics, with increasing of Er3+ content from 0.1 to 2.0mol%, the FWHM values of the emission bands increased from 42 to 71nm; meanwhile, the lifetime of 4I13/2 level slightly reduced. However, both the values of FWHM and lifetime were larger than those of precursor glasses due to the change of ligand field of Er3+ ions. [Copyright &y& Elsevier]

The poor operational stability of perovskite light-emitting diodes (PeLEDs) remains a major obstacle to their commercial application. Achieving high brightness and quantum efficiency at low driving voltages, thus effectively reducing heat accumulation, is key to enhancing the operational lifetime of PeLEDs. Here, we present a breakthrough, attaining a record-low driving voltage while maintaining high brightness and efficiency. By thoroughly suppressing interface recombination and ensuring excellent charge transport, our PeLEDs, with an emission peak at 515 nanometers, achieve a maximum brightness of 90,295 candelas per square meter and a peak external quantum efficiency of 27.8% with an ultralow turn-on voltage of 1.7 volts (~70% bandgap voltage). Notably, Joule heat is nearly negligible at these low driving voltages, substantially extending the operational lifetime to 7691.1 hours. Our optimized strategies effectively tackle stability issue through thermal management, paving the way for highly stable PeLEDs. [ABSTRACT FROM AUTHOR]

A new strategy of synthesizing hexagonal upconversion NaYF4at low temperature (down to 130 °C) based on Ti4+doping-induced cubic-to-hexagonal phase transition in a liquid–solid–solution reaction system is offered. [ABSTRACT FROM AUTHOR]

Complete phase transition from hexagonal LnF3(Ln3+= La3+, Ce3+, Pr3+) to monodisperse ultrasmall (∼7 nm) cubic Ln0.8M0.2F2.8(M2+= Ca2+, Sr2+, Ba2+) disordered solid solution nanocubes was successfully achieved through alkaline-earth doping, which induced great intensification of the near-infrared to visible upconversion emissions of the optically active rare earth ions. [ABSTRACT FROM AUTHOR]

The Eu3+ and Tb3+ doped glass ceramics containing tetragonal LiYbF4 nanocrystals were prepared. The Stark splitting emission, the low electric dipole 5D0→7F2 transition, and the long lifetime of Eu3+ evidenced the partition of rare earth into LiYbF4. For Tb3+ doped glass ceramic, intense ultraviolet emission of Tb3+: 5G6, 5D3→7F6 transition via cooperative sensitization of Yb3+ and bright blue cooperative luminescence originated from the coupled state of Yb3+–Yb3+ ionic pairs were achieved under 976 nm excitation, ascribing to the low-phonon-energy environment of rare earth ions enriched in nanocrystals and the efficient Yb3+–Tb3+ or Yb3+–Yb3+ interionic interactions. [ABSTRACT FROM AUTHOR]

Recently, semiconducting chalcogenide nanostructures have attracted intense attention due to their excellent properties and broad applications, especially metal chalcogenides in the form of A2(V)B3(VI). Here we synthesized one-dimensional (1D) bismuth sulfide (Bi2S3) nanostructures with a length of more than 100 μm via a one-step hydrothermal method, and found that the reaction temperature and the alkali concentration play vital roles in the morphology of the 1D nanostructures. Since the as-synthesized Bi2S3 nanostructures were disordered in powder form, it is necessary to align them with ordered orientation and uniform distribution before further application. A blown bubble method was specifically applied to align these ultralong 1D nanostructures, and the assembly mechanism was also deeply analyzed, including the drift of nanostructures in the bubble film thickness direction, the relationship between (nanowire) NW spacing and array density, and the angle deviation of aligned arrays assembled from different bubble solutions. Interestingly, the initial straight Bi2S3 NWs could also be converted into buckled nanosprings (NSs) with regular pitches during the assembly process, and different NS formation stages were observed. A possible deformation mechanism or load bearing model of the wavy NS was proposed and verified, and the Young’s modulus of an individual NW was figured out for the first time. After annealing under a N2 atmosphere, the aligned Bi2S3 NWs embedded in the bubble film were exposed, and the clean arrays were fabricated into functional optoelectronic devices such as photodetectors with a high performance. [ABSTRACT FROM AUTHOR]

Skin wound healing is a dynamic and complex process that involves multiple physiological and cellular events. Grape seed proanthocyanidins (GSP) have strong anti-oxidation and elimination of oxygen free radicals, and have been shown to significantly promote wound healing, but the underlying mechanism remains unclear. Studies have indicated that reactive oxygen species (ROS) acts as an upstream signal to induce mitophagy, suggesting that GSP can regulate mitophagy through the signal pathway. This study aimed to investigate whether GSP regulates mitophagy by down-regulating oxidative stress to promote wound healing. In vivo , GSP treatment accelerated wound healing, granulation tissue formation, collagen deposition, and angiogenesis in mice. Moreover, GSP down-regulated ROS levels and promoted the expression of antioxidant proteins by up-regulating the expression of p-JNK/FOXO3a protein, thereby regulating the expression of mitophagy-related proteins. In vitro , 4 μg/mL GSP showed no apparent toxic effects on cells and effectively reduce the oxidative stress damage of cells induced by H 2 O 2. Western blot and superoxide anion fluorescence probe further confirmed that GSP effectively reduced Dihydroethidium content and up-regulated the expression of antioxidant proteins by activation of p-JNK/FOXO3a protein expression, thereby regulating mitophagy. Taken together, the findings from in vitro and in vivo experiments provide new insights into the promotion of wound healing by GSP. Schematic illustration of how GSP promotes wound healing in mouse skin by regulating endothelial mitophagy through the p-JNK/FOXO3A/ROS signaling pathway. Mice were administered GSP via gavage, which upregulated p-JNK protein. Phosphorylated JNK protein activated FOXO3a protein, which in turn upregulated antioxidant proteins (MnSOD and catalase) to reduce ROS levels. The decrease in ROS level regulated mitophagy and accelerated wound healing in mice. [Display omitted] • Grape seed proanthocyanidins (GSP) promotes wound healing. • GSP reduces oxidative stress to regulate mitochondrial autophagy. • The p-JNK/FOXO3a/ROS signaling pathway is regulated by GSP. [ABSTRACT FROM AUTHOR]