Bright YAG:Ce Nanorod Phosphors Prepared via a Partial Wet Chemical Route and Biolabeling Applications

Unraveling the Defect-Related Luminescence in a Eu2+-Doped Chlorosilicate Phosphor

Defects play non-negligible roles in many luminescent processes, where the significant and remarkable influence in the phosphor performance in various ways is observed. A full and clear perception of defects would be beneficial for the further development of the luminescence mechanism and design of phosphors. In this study, the defect-related luminescence in a chlorosilicate phosphor Ca₂SiO₃Cl₂: Eu²⁺ was deeply studied. Except for the green emission originating from the d-f transition of the Eu²⁺ ion, a blue emission band with unique sensitivity to temperature and excitation energy was confirmed to be induced by the defects. The defects related to anion vacancies in the material acted as electron traps and luminescence centers simultaneously, which were well-identified by luminescence spectra and theory calculation analysis. This study uncovered the peculiar behavior and action mechanism of defects in the luminescence process and demonstrates a new path to understanding the origin of the luminescence center.

Coordination ability determined transition metal ions substitution of Tb in Tb-Asp fluorescent nanocrystals and a facile ions-detection approach

Although the synthesis and fluorescent properties of lanthanide-amino acid complex nanostructures have been investigated extensively, limited studies have been reported on metal ions' substitution ability for the lanthanide ions in the complex and their effect on the fluorescent property. In this study, taking biocompatible Tb-aspartic acid (Tb-Asp) complex nanocrystals as a model, the substitution mechanism of metal ions, particularly transition metals, for Tb ions in Tb-Asp nanocrystals and the change in the fluorescent property of the Tb-Asp nanocrystals after substitution were systematically investigated. The experimental results illustrated that metal ions with higher electronegativity, higher valence, and smaller radius possess stronger ability for Tb ions' substitution in Tb-Asp nanocrystals. Based on the effect of substituting ions' concentration on the fluorescent property of Tb-Asp, a facile method for copper ions detection with high sensitivity was proposed by measuring the fluorescent intensity of Tb-Asp nanocrystals' suspensions containing different concentrations of copper ions. The good biocompatibility, great convenience of synthesis and sensitive detection ability make Tb-Asp nanocrystals a very low cost and effective material for metal ions detection, which also opens a new door for practical applications of metal-Asp coordinated nanocrystals.

Down-Conversion Nitride Materials for Solid State Lighting: Recent Advances and Perspectives

Advances in solid state white lighting technologies witness the explosive development of phosphor materials (down-conversion luminescent materials). A large amount of evidence has demonstrated the revolutionary role of the emerging nitride phosphors in producing superior white light-emitting diodes for lighting and display applications. The structural and compositional versatility together with the unique local coordination environments enable nitride materials to have compelling luminescent properties such as abundant emission colors, controllable photoluminescence spectra, high conversion efficiency, and small thermal quenching/degradation. Here, we summarize the state-of-art progress on this novel family of luminescent materials and discuss the topics of materials discovery, crystal chemistry, structure-related luminescence, temperature-dependent luminescence, and spectral tailoring. We also overview different types of nitride phosphors and their applications in solid state lighting, including general illumination, backlighting, and laser-driven lighting. Finally, the challenges and outlooks in this type of promising down-conversion materials are highlighted.