Le Wang,Ran Wei,Peng Zheng,Shihai You,Tian-Liang Zhou,Wei Yi,Takashi Takeda,Naoto Hirosaki,Rong-Jun Xie
As a new generation advanced display or projection technology, laser displays or projectors have attracted great attention owing to their ultra-high brightness, energy saving nature, brilliant image quality and/or large sizes. However, for laser displays or projectors without using three primary laser diodes, the lack of appropriate blue-laser-driven color converters is a big limitation and challenge. In this work, we propose to develop laminated phosphor-in-glass (PiG) films as laser-driven color converters for wide-color-gamut and high-brightness laser displays. The β-Sialon:Eu and CaAlSiN3-LiSi2N2-Si2N2O, Calson:Ce phosphors were chosen as the green and orange emitters, respectively, and were co-fired with glass frits on a sapphire substrate to form PiG films. No interfacial reactions between phosphors and glass were identified, and phosphor powders were uniformly distributed in the glass matrix. The phosphor content and the film thickness had an influence on the microstructure, luminance saturation and optical properties of the PiG films under laser light irradiation; both PiG films reached a maximum luminance saturation of 6.09 W mm−2 when their microstructures were optimized. The lamination architecture of the PiG films had a great impact on the optical properties of the laser-driven white light, and the maximum ones were achieved as the green-emitting PiG film was positioned on the orange-emitting film adhered to the sapphire substrate. Under 4.82 W mm−2 blue laser excitation, the laminated double-layer PiG films enabled the creation of white light with a wide color gamut of 107% NTSC, luminous efficacy of 74.44 lm W−1, luminous flux of 282.13 lm and color temperature of 7902 K. These results indicate that the laminated PiG films are promising color converters for use in high-power and wide-color-gamut laser displays or projectors.
Shan shan Zhao,He-He Dong,Weichang Li,Lei Zhang,Shikai Wang,Chun Yu,Hu Li
Upconversion emission materials have many advantages, such as narrowband sharp line emission, excellent photochemical stability, and long lifespan. In particular, under 980 nm invisible laser-beam irradiation, materials with visible light upconversion luminescence have vital application value in optical anti-counterfeiting and laser displays. In this study, a library of upconversion phosphors of CaLaAl3O7:RE3+/Yb3+ (RE=Tm, Ho) was produced through a high-temperature solid-state reaction method. The powders exhibited different color emissions under different excited wavelengths. Under 980 nm laser excitation, Tm3+/Yb3+ co-doped phosphors exhibited upconversion emission of 474 nm blue light, which was attributed to the 1G4→3H6 transition of Tm3+, and the fitting slope of the upconversion luminescence intensity vs. laser-pump power density was n450-500=2.83, which indicated the three-photon absorption upconversion process. Additionally, Ho3+/Yb3+ co-doped phosphors had the strongest red emission at 660 nm, originating from the 5F4/5S2→5I8 transition of Ho3+, which belongs to the two-photon absorption process. Subsequently, the changes in chromaticity coordinates of the prepared samples were analyzed under different light excitations, and different light color emissions were observed. The color purities of Ho3+/Yb3+ and Tm3+/Yb3+ co-doped samples were 99.9% and 65.4%, respectively. Finally, we verified the practical application value of the prepared powder in the fields of multi-color luminescence optical anti-counterfeiting and laser displays. The results show that the produced phosphors have vital application potential in information security protection, optical data storage, and 3D laser displays.
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