Hong Ha Thi Vu

Facile synthesis of bifunctional silica-coated core–shell Y2O3:Eu3+,Co2+ composite particles for biomedical applications

In the present study, bifunctional silica-coated Y2O3:Eu3+,Co2+ spherical-shaped submicron composite particles were successfully prepared using a facile urea-assisted homogenous precipitation method. Synthesized Y2O3:Eu3+,Co2+ phosphor composites showed both ferromagnetic behaviour and strong visible red luminescence emission. The surface of the Y2O3:Eu3+,Co2+ phosphor composites was modified with a thin silica layer to enhance the luminescent properties and obtain higher biocompatibility of the samples. The composite particles with silica coatings resulted in a small decrease in the viability of L-929 fibroblastic cells at concentrations lower than 25 ppm and allowed cell imaging via internalization and wide distribution into the cells. Overall, these synthesized novel SiO2@Y2O3:Eu3+,Co2+ core–shell phosphor composites with both magnetic and luminescent properties have potential biomedical applications, including bioimaging and diagnosis, and can be also potentially used as MRI contrast agents.

Luminescent core–shell Fe3O4@Gd2O3:Er3+, Li+ composite particles with enhanced optical properties

Abstract Bifunctional magneto-optical nanocomposites with Fe3O4 nanoparticles as a core and erbium and lithium codoped gadolinium (Gd2O3:Er3+, Li+) as the shell were synthesized successfully using a simple urea homogeneous precipitation method. The fabricated Fe3O4@Gd2O3:Er3+, Li+ particles were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy and quantum design vibrating sample magnetometry. The upconversion emission intensity was enhanced significantly comparing to that without Li+ ions. These bifunctional composites are expected to be potentially applied for drug delivery, cell separation and bioimaging.

Dye-sensitized solar cells composed of photoactive composite photoelectrodes with enhanced solar energy conversion efficiency

Phosphor particles were introduced as a luminescent medium to improve the overall efficiency of dye sensitized solar cells (DSSCs). In the preparation process, TiO2 and phosphor particles were mixed to make photoelectrodes with bilayer (TiO2/mix), 3-layer (TiO2/mix/TiO2) and 4-layer (TiO2/mix/TiO2/mix) structures. The cell with the bilayer structure (TiO2/mix) after treating with TiCl4 solution showed the highest light-to-electric energy conversion efficiency (8.78%), which was ∼25.8% higher than that of a cell with a pure TiO2 layer under the same experimental conditions. The improvement in the energy conversion efficiency of DSSCs was attributed to phosphor enhanced incident light-harvesting via up- and down-conversion luminescence processes, resulting in an increase in the photocurrent.

Effects of Li

Rare-earths codoped long afterglow strontium aluminate phosphors with high brightness were synthesized via a facile combustion synthesis method using urea as a fuel. The resulted phosphor particles were analyzed by using X-ray diffraction and field emission scanning electron microscope, whereas their optical properties were monitored by photoluminescence spectroscopy. The prepared SrAl2O4:Eu2

The Effects of WO₃ Nanoparticles Addition to the TiO₂ Photoelectrode in Dye-Sensitized Solar Cells

Increasing the efficiency of dye-sensitized solar cells (DSSCs) by the fabrication of new photoelectrodes (PEs) is an important challenge. This study examined the photovoltaic parameters of DSSCs composed of a TiO₂ PE with WO₃ nanoparticles (NPs). A number of PEs with the same thickness but different concentrations of WO₃ NPs in the TiO₂PE were prepared. The morphology and structural properties of the prepared PEs were examined by field-emission scanning electron microscopy and X-ray diffraction, respectively. The effects of the WO₃ NPs mixing concentration on the efficiency of DSSCs were investigated under simulated solar light irradiation.