Lanthanide-based luminescent hybrid materials.

Uniform, spherical-shaped TiO2:Eu nanoparticles with different doping concentrations have been synthesized through controlled hydrolysis of titanium tetrabutoxide under appropriate pH and temperature in the presence of EuCl3·6H2O. Through air annealing at 500°C for 2 h, the amorphous, as-grown nanoparticles could be converted to a pure anatase phase. The morphology, structural, and optical properties of the annealed nanostructures were studied using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy [EDS], and UV-Visible diffuse reflectance spectroscopy techniques. Optoelectronic behaviors of the nanostructures were studied using micro-Raman and photoluminescence [PL] spectroscopies at room temperature. EDS results confirmed a systematic increase of Eu content in the as-prepared samples with the increase of nominal europium content in the reaction solution. With the increasing dopant concentration, crystallinity and crystallite size of the titania particles decreased gradually. Incorporation of europium in the titania particles induced a structural deformation and a blueshift of their absorption edge. While the room-temperature PL emission of the as-grown samples is dominated by the 5D0 - 7Fj transition of Eu+3 ions, the emission intensity reduced drastically after thermal annealing due to outwards segregation of dopant ions.

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Effects of crystallization and dopant concentration on the emission behavior of TiO2:Eu nanophosphors

Sasidharan Swarnalatha Lucky,†,§ Khee Chee Soo,‡ and Yong Zhang*,†,§,∥ †NUS Graduate School for Integrative Sciences & Engineering (NGS), National University of Singapore, Singapore, Singapore 117456 ‡Division of Medical Sciences, National Cancer Centre Singapore, Singapore, Singapore 169610 Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore, Singapore 117576 College of Chemistry and Life Sciences, Zhejiang Normal University, Zhejiang, P. R. China 321004

Nanoparticles in photodynamic therapy.

Yuming Yang,†,§ Qiang Zhao,‡,§ Wei Feng,† and Fuyou Li*,† †Department of Chemistry and State Key Laboratory of Molecular Engineering of Polymers and Institutes of Biomedical Sciences, Fudan University, Shanghai 200433, P. R. China ‡Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210046, P. R. China.

Luminescent chemodosimeters for bioimaging.

Applications in Theranostics Guanying Chen,*,†,‡ Hailong Qiu,†,‡ Paras N. Prasad,*,‡,§ and Xiaoyuan Chen* †School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin, Heilongjiang 150001, China ‡Department of Chemistry and the Institute for Lasers, Photonics, and Biophotonics, University at Buffalo, State University of New York, Buffalo, New York 14260, United States Department of Chemistry, Korea University, Seoul 136-701, Korea Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland 20892-2281, United States

Upconversion Nanoparticles: Design, Nanochemistry, and Applications in Theranostics

Persistent luminescence phosphors, which are capable of emitting light for a long time after ceasing excitation, have shown great promise in diverse areas as bioprobes, lighting and displays. Exploring new materials to realize efficient persistent luminescence is a goal of general concern. Herein, we report a novel persistent luminescence phosphor based on Eu3+-doped SnO2 nanoparticles (NPs). The afterglow decay behaviour, the trap depth distribution as well as the underlying mechanism for persistent luminescence of the NPs were comprehensively surveyed by means of thermoluminescence and temperature-dependent afterglow decay measurements. It was found that the thermal activation mechanism is responsible for the afterglow decay of the NPs with an inverse power-law exponent of 1.0 (or 1.7) in the temperature region below (or above) 220 K. In particular, the co-existence of uniform and exponential distributions in trap depths may result in such a unique afterglow decay behaviour. These results reveal the great potential of SnO2 NPs as an excellent host material for Eu3+ doping for the generation of efficient persistent luminescence.

Persistent luminescence from Eu3+ in SnO2 nanoparticles

Sm3+ and Dy3+ ions doped hexagonal wurtzite ZnO nanocrystals were fabricated by a sol-gel method The obtained ZnO nanocrystals were characterized using the X-ray diffraction, transmission electron microscopy, ultraviolet-visible reflectance spectra, and low-temperature luminescence spectroscopy Intense and well resolved emission lines for Sm3+ and Dy3+ ions can be achieved via an energy transfer process from ZnO host to the dopants It was found that the host sensitized emissions were more efficient than that of direct excitation for Sm3+ and Dy3+ ions Moreover, multiple sites of Sm3+ and Dy3+ ions in ZnO nanocrystals were identified based on the low-temperature photoluminescence spectra

Optical Spectroscopy of Sm3+ and Dy3+ Doped ZnO Nanocrystals

Water-soluble lanthanide-doped BaFCl nanophosphors with the surface functionalized by a layer of poly (acrylic acid) are synthesized via a facile one-step solvothermal method. Intense long-lived luminescence is realized from visible to near-infrared (NIR) by doping with different lanthanide ions. The emission and excitation spectra of Eu3+ indicate that the doped lanthanide ions occupy a site close to the surface of the nanoparticles. Strong NIR emissions of Nd3+ and green luminescence of Tb3+ using Ce3+ as sensitizers are also achieved in BaFCl nanoparticles. The synthesized nanoparticles featuring long-lived luminescence in either visible or NIR regions may have potential applications as luminescent labels for biological applications.

Poly (acrylic acid)-capped lanthanide-doped BaFCl nanocrystals: synthesis and optical properties

Yb:CaYAlO4 (Yb:CYA) crystals with good optical qualities have been grown by the Czochralski method. The detailed polarized spectral properties, including absorption and fluorescence, were investigated. The results reveal a broadband emission feature (FWHM=77 nm at σ polarization). The fluorescence lifetime has been measured using the powder concentration dilution method, and the intrinsic lifetime was found to be 426 μs. The thermal properties, including specific heat, thermal expansion, and thermal diffusion coefficients, have been investigated. The thermal conductivities were calculated to be 3.6 and 3.2 W/m/K along the a and c axes, respectively, at room temperature. The CW laser performances have been studied for both π and σ polarizations. The slope efficiencies of 55.4% and 41.4% were obtained for π- and σ-polarized operations, respectively. All the results show that Yb:CYA crystals should be excellent candidates as a laser medium for efficient and ultrafast lasers in the 1 μm region.

Characterization of laser crystal Yb:CaYAlO 4

Circularly polarized light (CPL)-sensitive direct detection is attracting increasing attention owing to its various optical technology applications and ultracompact device structures. However, current CPL-sensitive direct detection mainly focuses on a single mode, whereas the visible-near-infrared (vis-NIR) dual-modal detection, which is important for improving device sensitivity and night-vision performance, still remains to be explored. Here, for the first time, the vis-NIR dual-modal CPL-sensitive direct detection is presented in bulk single crystals of two-dimensional chiral perovskite (R-BPEA)2PbI4 (R-BPEA = (R)-1-(4-bromophenyl)ethylammonium). Benefiting from the strong light-matter interaction of the layered structure, (R-BPEA)2PbI4 shows a two-photon absorption (TPA) coefficient of up to 55 cm/MW, which almost falls around the highest value of 2D hybrid perovskites. Notably, (R-BPEA)2PbI4 exhibits a high vis-NIR dual-modal CPL-sensitive direct detecting performance under both visible light (520 nm) and NIR light (800 nm), with the on/off ratios of current higher than 103, and the anisotropy factors for photocurrent higher than 0.1. This work will shed light on the design of new chiral semiconductors with a large TPA coefficient and promote their applications in vis-NIR dual-modal CPL-sensitive direct detection.

Xueyuan Chen

Papers

Persistent luminescence from Eu3+ in SnO2 nanoparticles

Optical Spectroscopy of Sm3+ and Dy3+ Doped ZnO Nanocrystals

Poly (acrylic acid)-capped lanthanide-doped BaFCl nanocrystals: synthesis and optical properties

Characterization of laser crystal Yb:CaYAlO 4

Realization of vis-NIR Dual-Modal Circularly Polarized Light Detection in Chiral Perovskite Bulk Crystals.