A thermally robust phosphor-in-glass film with high luminous efficiency for high-power blue laser diodes lighting

Abstract

Thermally robust and high efficiency color converters with good thermal dispersion have attracted much attention for high power laser-lighting applications. Herein, the Y3Al3.08Ga1.92O12:Ce3+ (YAGG:Ce) phosphor-in-glass (PIG) film coated on single crystal sapphire of high thermal conductivity is fabricated by using a facile and industry friendly blade-coating technique. The as-sintered composite film displays a high internal quantum efficiency of 95.2%, a high transmittance of 45% in the wavelength of 300–800 nm, and superior thermal stability which can keep 90.2% of the room temperature intensity at 200 °C. Furthermore, when pumped by 450 nm blue laser diodes (LDs), the composite PIG film can tolerate the input power density of up to 16.2 W/mm2. Impressively, the composite PIG film with 50% phosphor content at a fixed thickness of 0.2 mm generates green light with a maximum luminous flux of 967 lm and a luminous efficiency of 167 lm/W under 12.86 W/mm2 blue laser irradiation. The above results validate that the composite PIG film is a considerably promising green color converter for high-power and high-luminance laser driven solid state lighting.