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ZnO-NaSrBO3:Tb3+ (ZNT) composites were successfully synthesized via microwave-assisted reaction of the ZnO precursor with a NaSrBO3:Tb3+ suspension using a microwave synthesis system. The morphology, structure and photocatalytic performance in the degradation of methylene blue (MB) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy, fluorescence spectrophotometry and electrochemical impedance spectroscopy, respectively. The results show that the ZNT composites exhibit enhanced photocatalytic activity in the degradation of MB with a maximum degradation rate of 97% under visible light irradiation compared with pure ZnO (12%), which is ascribed to the increased light absorption and the reduction of photoelectron-hole pair recombination in ZnO with the introduction of NaSrBO3:Tb3+, as well as the light down-converting effect of NaSrBO3:Tb3+, which facilitates the self-sensitized degradation of MB. [ABSTRACT FROM AUTHOR]

Red phosphors of Li-doped CaTiO3:Eu3+ that enhance photoluminescence have been synthesized by a solid-state method, and their structure and morphology were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The luminescence property was measured using photoluminescence excitation (PLE) and photoluminescence (PL) spectra, respectively. The effect of sintered temperature and Eu3+ and Li+ concentration in as-prepared series phosphors was studied. Results indicate that the optimal luminescence properties of CaTiO3:Eu3+ (CTE) phosphors are typically obtained at 1300 °C with 12 mol% of Eu3+ concentration, and the emission intensity can be greatly enhanced by the incorporation of Li+ into the CTE phosphors, attributing that Li not only compensates positive charge defect by replacement of Ca2+ with Eu3+, but also plays a role of flux, which could enhance the crystallinity of the phosphors. The intensity of the optimal Li-doped CaTiO3:Eu3+ phosphor (CLTE) is 2.3 times of that of CTE. PL spectrum showed that CLTE phosphor was efficiently excited by near-ultraviolet light at wavelength around 398 nm and emitted intensive red light with a peak around 616 nm corresponding to the 5D0→7F2 transition of Eu3+. Furthermore, this phosphor has very good thermal stability and high color purity, implying the potential to be a promising red phosphor in white light emitting diodes. [ABSTRACT FROM AUTHOR]

Long afterglow Sr4Al14O25:Eu,Dy phosphors were introduced into the TiO2 photoanode of CdS quantum dot-sensitized solar cells (QDSSCs) as both a scattering and down converting layer, and the photovoltaic performances of the cells were investigated. The results show that the cell with Sr4Al14O25:Eu,Dy achieves a power conversion efficiency of 1.40%, which is an increase of 38% compared to the cell without Sr4Al14O25:Eu,Dy (1.02%). The performance improvement is attributed to enhanced light harvesting via improved light absorption and scattering processes. After a single sun illumination for 1 min and subsequent removal of the light source, the cell with Sr4Al14O25:Eu,Dy could be driven even in the dark by the long persistent light from Sr4Al14O25:Eu,Dy. [ABSTRACT FROM AUTHOR]

Mn2+ doped-AlN red phosphors were prepared by the solid-state reaction method. X-ray diffraction, SEM-EDS, photoluminescence and cathodoluminescence were utilized to characterize the prepared phosphor. Under UV light or electron beam excitation, the AlN:Mn2+ phosphors exhibit a strong red emission centered at 600 nm, which is ascribed to the characteristic 4T1(4G)–6A1(6S) transition of Mn2+. Energy level diagrams were constructed to discuss the photoluminescence and cathodoluminescence processes of the AlN:1% Mn2+ phosphor. The oxygen-related defects in AlN have great influence on the photoluminescence and cathodoluminescence properties of the AlN:1% Mn2+ phosphor. The dependence of brightness on accelerating voltage or electric current, the decay behavior of CL intensity under the electron bombardment, and the stability of CIE chromaticity coordinates were investigated in detail. The results indicate that the AlN:Mn2+ phosphor exhibits a higher brightness, higher color purity, and lower saturation compared to the red Y2O3:Eu3+ phosphor, which gives the AlN:Mn2+ phosphor great potential as a red phosphor for full color FEDs. [ABSTRACT FROM AUTHOR]

An Eu2+-activated BaSi7N10 cyan phosphor for UV-pumping white light-emitting diodes (LEDs) was successfully synthesized by direct gas reduction and nitridation of the homogeneous oxide precursor of a BaO-SiO2-Eu2O3 system in flowing NH3 and CH4 mixture gas. The phase purity, morphology, chemical composition, and luminescence properties were investigated. The effect of activator concentration on the optical properties of Eu2+ in BaSi7N10 was discussed. The synthesized powders have a nearly pure BaSi7N10 phase and consist of microsized particles. Eu2+-doped BaSi7N10 phosphors absorb strongly in the UV part of the electromagnetic spectrum and exhibit an intense cyan emission band centered at 482-500 nm, which agrees with earlier papers. The optical properties depend greatly on the Eu2+ concentration. Under an UV excitation, BaSi7N10:Eu2+ phosphors doped with a 20 atom % activator give the best luminescent properties, such as high emission intensity, high quantum efficiency, and very low thermal quenching, which suggests that Eu2+-doped BaSi7N10 can be a good green-blue phosphor for UV-pumping white LEDs. [ABSTRACT FROM AUTHOR]

This paper reports a low-cost yellow-orange emitting Y3Al5−xSixO12−xNx:Ce3+ phosphor with excellent color rendering for warm white LEDs. It was synthesized by a simple gas pressure sintering (GPS). The effect of Si4+—N3− incorporation on the optical properties of Y3Al5O12:Ce3+ phosphor was investigated. The addition of Si3N4 leads to an obvious shift of its emission spectra toward the red region and an increase of FWHM accompanying a significant decrease of photoluminescent intensity, which is assigned to incorporation of N3− in Ce3+ nearest neighbor coordination. Adding nanosized amorphous Si3N4 or flux can greatly improve the emission intensity of Y2.925Ce0.075Al5−xSixO12−xNx phosphor. Finally, the white LED flat lamp with a CRI as high as 83, luminous efficiency of 65 lm/W, and CCT of about 3700 K is successfully realized by using a single oxynitride phosphor combined with a blue LED chip, which is acceptable for general indoor illuminations to replace fluorescent or incandescent lamps. [ABSTRACT FROM AUTHOR]