A full-spectrum color converter based on tricolor phosphor-in-glass films for laser-driven white lighting

Abstract

Full-spectrum laser-driven white lighting shows promise for high-luminance solid-state illumination and is highly desirable for lighting application domains such as education, healthcare, and residential lighting. However, obtaining both a high color rendering index (Ra) and high luminous efficiency (LE) concurrently poses a great challenge for the development of laser-driven white lighting. Herein, a novel tricolor phosphor-in-glass film (PiGF) is designed and fabricated via a facile low-temperature co-sintering strategy. ZnO–Li₂O–SiO₂ (ZLS) glass along with Y₃Al₅O₁₂:Ce³⁺ (YAG), CaAlSiN₃:Eu²⁺ (CASN), and Lu₃(Al, Ga)₅O₁₂:Ce³⁺ (LuAGG) phosphors was coated onto sapphire substrates via the blade-coating method and then subjected to low-temperature co-firing, fabricating composite phosphor-in-glass film (PiGF) samples for full-spectrum laser-driven white lighting. High LE and Ra were achieved by optimizing the glass layer thickness, phosphor concentrations, phosphor ratio, film structure, and sintering process. The YAG-PiGF achieves a high luminous flux (LF) of 1129 lm and a Ra of 62. Further addition of CASN and LuAGG phosphors fills the color gaps, resulting in a composite PiGF with a high Ra of 92 and a LE of 212 lm W⁻¹. The excellent balance between Ra and LE makes this color converter highly promising for high-quality laser lighting applications.