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Highly luminescent Cd-free Zn doped CuInS2 nanocrystals (ZCIS NCs) were synthesized, and their properties were evaluated using Xray diffraction, Raman, UV, and photoluminescence. The crystal structure of the ZCIS NCs was similar to the zinc blende, and the lattice constant decreased with increasing Zn concentration. By incorporation of Zn, the emission wavelength was tuned from 536 to 637nm with concomitant enhancement of the quantum yield up to 45%. A white light emitting diodes, integrating dual ZCIS NCs (lambda(em) = 567, and 617nm) and a 460nm InGaN LED, exhibited a high color rendering index of 84.1 with a warm color temperature of 4256.2K. The CIE-1931 chromaticity coordinates were slightly shifted from (0.3626, 0.3378) at 20mA to (0.3480, 0.3206) at 50mA. (C) 2012 Optical Society of America

The spherical and submicron size of Sr₁-xCaxSe:Eu²⁺ phosphors were successfully prepared by ultrasonic spray pyrolysis. The phosphors adopted a cubic structure, and the replacement of Sr²⁺ with Ca²⁺ decreased the lattice parameter. The Sr₁-xCaxSe:Eu²⁺ showed broad and strong excitation under 420-460 nm blue light, and the emission band could be tuned from 565 to 607 nm by increasing the Ca²⁺ ratio in the host lattice. In addition, the doping of Zn²⁺ into Sr²⁺ or Ca²⁺ enhanced the emission intensity with a small red shift due to the change in crystal field strength and nephelauxetic effects. The warm and high CRI of white LED was achieved using blue LED pumped with blending phosphors of 612 nm emitting Ca₀.₉₈Zn₀.₀₂Se:Eu²⁺ and 565 nm emitting YAG. The correlated color temperatures and CRI were 4719.2K, and 86.3, respectively, and an acceptable color variation was also observed at operating currents ranging from 20 to 70 mA.

In this study, non-toxic and highly stable silica coated ZnCuInS NCs were synthesized by a reverse microemulsion method. The single NCs were uniformly encapsulated in a silica shell with a diameter of similar to 30nm. Although hydrolyzed TEOS caused a QY reduction, and a 12.5nm red shift occurred after silica coating, the photo and thermal stabilities were extremely improved. For LED application, the silica coated ZnCuInS NCs phosphor layer was arrayed on the InGaN LED surface by layer-by-layer deposition utilizing electrostatic attraction. When the ZnCuInS/SiO2 NCs single monolayer was fabricated, 6.73% high color conversion efficiency was achieved. (C)2014 Optical Society of America

The spherical and submicron size of Sr1-xCaxSe:Eu2+ phosphors were successfully prepared by ultrasonic spray pyrolysis. The phosphors adopted a cubic structure, and the replacement of Sr2+ with Ca2+ decreased the lattice parameter. The Sr1-xCaxSe:Eu2+ showed broad and strong excitation under 420-460nm blue light, and the emission band could be tuned from 565 to 607nm by increasing the Ca2+ ratio in the host lattice. In addition, the doping of Zn2+ into Sr2+ or Ca2+ enhanced the emission intensity with a small red shift due to the change in crystal field strength and nephelauxetic effects. The warm and high CRI of white LED was achieved using blue LED pumped with blending phosphors of 612nm emitting Ca0.98Zn0.02Se:Eu2+ and 565nm emitting YAG. The correlated color temperatures and CRI were 4719.2K, and 86.3, respectively, and an acceptable color variation was also observed at operating currents ranging from 20 to 70mA. (c) 2012 Optical Society of America