High-Efficiency Red-Emitting Phosphor-In-Glass Films for Laser-Driven Lighting and Display

Abstract

Laser-driven phosphor-converted lighting and display technologies offer exceptional energy efficiency and superior performance. However, the development of high-quality white light sources with both excellent color rendering and high brightness remains a significant challenge due to the scarcity of red-emitting color converters that maintain high efficiency and stability under high laser powder densities. In this study, (Sr, Ca)AlSiN₃: Eu²⁺ (SCASN:Eu) phosphor-in-glass films (PiGFs), emitting from 610 to 680 nm, are fabricated on Al₂O₃ ceramic substrates with minimal interfacial reactions. All PiGFs exhibited excellent densification and maintained high IQE, losses in IQE remaining below 10 % relative to the original phosphor. Notably, the PiGF with an emission peak at 653 nm achieved a lumen density of 206 lm mm⁻² @ 23.6 W mm⁻² due to its high thermal conductivity (22 W m⁻¹ K⁻¹) and low IQE loss. Under rotating excitation, it reached a record 786 lm mm⁻² @ 90.6 W mm⁻². Furthermore, a spatially separated YAGG:Ce-CASN:Eu “phosphor wheel” in reflective mode produced a luminous flux of 1125 lm @ 23.6 W mm⁻², a correlated color temperature (CCT) of 6653 K, a color rendering index (CRI) of 86, and CIE coordinates (0.308, 0.338), enabling long-distance illumination and projection display. This work offers a promising strategy for developing high-efficiency color converters for advanced laser-based lighting and display applications.