White light emission from a blue LED,combined with a sodium salt of fluorescein dye

The bivalent sodium salt of fluorescein dye was successfully isolated. The maximum absorption and fluorescence emission wavelengths of the isolated fluorescein salt in epoxy were about 470 and 540 nm, respectively. The fluorescence quantum yield of the isolated salt in an epoxy matrix was measured to be 0.94. A hybrid light-emitting diode (LED) was fabricated using a blue light-emitting diode (LED, 460 nm) and the fluorescein salt dispersed in epoxy as the primary light source and luminescence converter, respectively. White light emission was observed when the salt concentration in the epoxy was 0.04 wt%. In the presence of DCM2 (a red dye, 8 wt% based on the salt), the CIE color coordinates of the hybrid LED system were closer to the pure white point. The conversion efficiencies of the system with and without DCM2 were 68 and 84%, respectively, which are higher than those reported so far in the literature.     

Eu/Sm ions co-doped white light luminescence SrSiO3 glass-ceramics phosphor for White LED

Eu²⁺/Sm³⁺ co-doped silicate glass was prepared by high temperature melting under reducing atmosphere and the Eu²⁺/Sm³⁺ co-doped SrSiO₃ transparent glass-ceramics were obtained after heat-treatment. X-ray diffraction (XRD) and Raman spectra confirmed the formation of SrSiO₃ nano-crystals in the glass matrix. The photoluminescence excitation (PLE) spectra and photoluminescence (PL) spectra of the samples were measured. A broad emission band from 400 nm to 550 nm due to the 4f⁶5d¹ → 4f⁷ transitions of Eu²⁺ was observed, as well as several sharp emission peaks at 563 nm, 600 nm, 646 nm and 713 nm ascribed to the 4f → 4f transitions of Sm³⁺. The luminescence properties of the glass ceramics with different molar ratio of Eu²⁺/Sm³⁺ were studied and the corresponding chromaticity coordinates were calculated. The ultraviolet light-emitting diode (UV-LED) excitable glass-ceramics emitting white light were obtained by tuning the relative emission intensity of Eu²⁺ and Sm³⁺. The results indicate that the Eu²⁺/Sm³⁺ co-doped SrSiO₃ transparent glass-ceramics can be used as a potential matrix material for White LED under UV-LED excitation.     

White light emission from two blue emitters of an equimolar (1:1) blend in single-layer device

A white light emission was observed from a single-layer emitting system consisting of an equimolar blend of two blue emitters of a bipolar oligomer, 9,9-spirobifluorene-centered bioxadiazole (303) and polyvinylcarbazole (PVK), featuring a single broad emission (ranging in 400–800 nm), which is distinctly different from those of large PVK-fraction blends (λ_em ≈ 490 nm) and that of pristine 303 (λ_em ≈ 555 nm) as well.     

Co-Fe quantum dots coupled with ultrathin g-C3N4 nanosheets as efficient and stable photo-Fenton catalysts

The Fenton reaction has been widely used in the environmental remediation.However,the sharp decline of photo-Fenton catalysts activity under neutral conditions is still an urgent problem to be solved.This study reports a Co/Fe bimetallic oxide quantum dots-coupled g-C₃N₄nanosheets(CoFeO QDs/g-C₃N₄ NS s) composites with efficient degradation of organic pollutants under neutral conditions.Under the photo-Fenton condition,rhodamine B(RhB) degradation effi...     

White light electroluminescence from PSi devices capped with poly(thiophene)(s) as top contact

For the first time, electrochemically deposited poly(3-methylthiophene) and chemically produced poly(3-methylthiophene) and poly(3-phenoxymethylthiophene) have been employed as top electrical contact on porous silicon light-emitting devices. The polymer-capped devices emitted white light as opposed to the uncapped devices, which emitted orange colour. The polymer-capped devices show much higher rectification ratio (up to 1×10⁵) as opposed to 1×10³ for the uncapped devices at ±10 V. The polymer-capped devices show 10³–10⁴-fold improvement in the luminous efficiency over the uncapped devices. Electrochemically deposited poly(3-methylthiophene) top contacts give a luminous efficiency of 8×10⁻⁵ lm W⁻¹ as opposed to 3×10⁻⁹ lm W⁻¹ obtained from uncapped devices. All the devices were found to fit the space charge limited current model.