Realizing high-brightness and ultra-wide-color-gamut laser-driven backlighting by using laminated phosphor-in-glass (PiG) films

Abstract

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.