High performance composite phosphor-in-glass film for laser-driven warm white light on patterned sapphire substrate

Abstract

Phosphor-in-glass film (PiF) based on sapphire substrate (SS) is a promising laser-driven color converter. Herein, by using an optimized silicon borate glass component, high-performance Y₃Al₅O₁₂:Ce³⁺ PiFs are successfully prepared on both flat sapphire substrate (FSS) and patterned sapphire substrate (PSS) surfaces. Compared with planar structure of FSS, PSS has a periodic arrangement of conical structures on its surface, which effectively increases the contact area between the PiF and the substrate by approximately 56%, thereby forming a more robust film composite structure. The blue laser light is affected by the structure of PSS and produces a typical diffraction effect, which realizes the dispersion of the convergent beam. This significantly expands the laser spot on PSS-PiF and improves the uniformity of light. The saturation power density of PiF-PSS (6.29 W/mm²) is found to be 91% higher than that of PiF-FSS, while maintaining a high luminous efficiency (220 lm/W) and a low correlated color temperature (4500 K). Finally, the thermal quenching mechanism of PiF with different substrate surface morphologies is compared and analyzed. The present results provide important support for designing the interface structure between SSs and PiF to achieve higher efficiency and higher saturation threshold for warm white light.