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A novel Sr 3 Ti 2 O 7 :Eu 3+ red phosphor with double-layered perovskite structure was successfully synthesized by solid-state reaction method using Li + ions as charge compensators. Its crystal structure, morphology and photoluminescence under different calcination temperatures and different compensation styles of Li + were investigated. The phosphor could obtain pure tetragonal perovskite phase with I4/ mmm space group at 1300 °C. Non-stoichiometric (NSC) compensation could keep more Sr 2+ ions to hold the perovskite structure stable for higher doping concentration of Eu 3+ . The emission was dominated by the electric-dipole transition with obvious peak splitting due to two different doping sites with lower symmetry of Sr 2+ . Layered structure provided bigger space to hold more Li + ions and NSC style had bigger advantage on the luminescence enhancement for higher doping concentration. Better excitation matches, higher quantum yield (25.1%, λ ex = 395 nm) and better color rendering properties provided a potential red material for white LEDs. [ABSTRACT FROM AUTHOR]

Series of Eu 3+ substituted Na(Gd 1− x Eu x )MgWO 6 phosphors were successfully synthesized by a EDTA-citric acid complexing method. The crystal structure, doping site, morphology, and luminescent properties under different Eu 3+ concentrations were investigated by XRD, Rietveld refinement, Raman spectra, FTIR, SEM and fluorescence spectra as well as Judd–Ofelt analysis and quenching theory. The phosphors had monoclinic double perovskite structure with space group C2/m , rock-salt ordering of B-site (Mg/W) and layered ordering of A-site (Na/Gd/Eu). The redshift of Raman T 2g (1) mode proved Eu 3+ ions had uniformly substituted into A-site. The rare alternative excitation appeared in phosphors that the charge transfer band (CTB) altered from O–W into O–Eu and the strongest excitation altered from CTB into f – f transition of Eu 3+ . The quenching concentration for hypersensitive 5 D 0 – 7 F 2 transition of Eu 3+ reached up to 50.0 mol%, while both the intensity ratio of 5 D 0 – 7 F 2 / 5 D 0 – 7 F 1 and Judd–Ofelt parameter Ω 2 reached the maximum. These two channels of alternative excitation and delayed concentration quenching dually enhanced the luminescence of NaGdMgWO 6 :Eu 3+ phosphor. It is a potential red material for NUV and blue LED chips. [ABSTRACT FROM AUTHOR]

• Low-cost flexible transparent conductive oxide (TCO) film. • Low-cost, indium-free and flexible perovskite CaVO 3 TCO films grown on mica substrates. • Superior stable optical transparency and electrical conductivity after 105 bending cycles. Transparent conducting oxides (TCOs), such as indium-tin oxide (ITO) and indium gallium zinc oxide (IGZO), are essential components in the design of flexible optoelectronic devices. However, it is still a challenge to prepare low-cost flexible transparent conductive film for achieving the flexible functionality together with high optical transparency and electrical conductivity. Herein, fluorphlogopite (mica) is selected as the bendable and transparent substrate for the fabrication of low-cost perovskite CaVO 3 TCO epitaxial film. Benefitting from thin mica substrate with high Young's modulus of 200 GPa, flexible CaVO 3 TCO epitaxial film exhibits high mechanical stability in terms of electrical conductivity and optical transparency after bending up to 105 cycles. The change of resistance can reflect the bending curvature and strain state. Our results provide a new pathway to design superior mechanical flexibility and stability CaVO 3 TCO films for application in flexible, light-weight, and portable smart optoelectronic devices. [ABSTRACT FROM AUTHOR]

Abstract: Double perovskite (Sr0.98− m Ba m Eu0.02)2Ca(Mo1− n W n )O6 phosphors were successfully synthesized by an improved citrate–EDTA complexing method. The structure evolution and the resulting luminescence variation were systematically investigated by X-ray diffraction with Rietveld structure refinement, Fourier transform infrared spectra, Raman spectra, diffuse reflection spectra and photoluminescence spectra. The increased crystal symmetry and increased lattice parameters were observed from (Sr0.98− m Ba m Eu0.02)2CaMoO6 phosphors. These series of phosphors could be effectively excited by near ultraviolet light and emitted a dominant 594nm (5D0–7F1). The hypersensitive 5D0–7F2 transition (615nm) varied with the changed structure symmetry. The CIE chromaticity coordinates were tuned from (0.642, 0.348) to (0.601, 0.389). The luminescence intensity of W6+ substituted powders was greatly enhanced by the blue shift of charge transition band of (Mo/W)O6 with stable emission color. The composition-optimized Sr2Ca(Mo0.5W0.5)O6:Eu phosphor had the highest luminescence intensity and quantum yield comparing to the commercial red phosphors. [Copyright &y& Elsevier]