Design of a β-SiAlON:Eu based phosphor-in-glass film with high saturation threshold for high-luminance laser-driven backlighting

β-Si6−zAlzOzN8−z:Eu2+ (β-SiAlON:Eu) possesses an intense and narrow emission band peaked at ∼530 nm, which makes it a highly suitable green-emitting phosphor for LCD backlight. However, it can hardly be used in high-power laser displays or projectors because of the laser-induced saturation effect. The aim of the present study is to develop a β-SiAlON:Eu based phosphor-in-glass (PiG) film that can withstand high-power density laser irradiation.

A facile blade-coating method was employed to fabricate the PiG film. The morphology, quantum efficiency, luminescence spectra, and laser-pumped colorimetric properties of the β-SiAlON:Eu PiG films were investigated. Under excitation of 450 nm, a typical PiG film showed internal quantum efficiency of 58%, which is an acceptable value.

The laser-pumped photometric properties of the PiG films were measured in reflection mode. When irradiated with a blue laser, the PiG film attained a high luminous efficacy of 109 lm/W. Furthermore, its saturation threshold reached over 26.4 W/mm2, thus achieving a high lumen density of 1970 lm/mm2 and a high luminous exitance of 1052 lm/mm2.

With the above excellent properties, the β-SiAlON:Eu PiG film has great potential for use in high-power and wide-color gamut laser displays or projectors.