Enhancing thermal stability and color quality of YAG:Ce scintillator excited by laser-based solid-state lighting

Abstract Laser-based solid-state lighting (LB-SSL) is a crucial step towards achieving net-zero carbon emissions by 2050. In LB-SSL, a single yellow phosphor, typically cerium-doped yttrium aluminum garnet, (widely known as as YAG:Ce) is excited by a laser beam to generate white light. The resultant emission exhibits poor heat dissipation and limited color quality due to spectral deficiency when compared with full-spectrum natural sunlight. This study examines the viability of combining red-emitting SrAlSiN ₃ :Eu 2+ and green-emitting SrBaSiO ₄ :Eu 2+ phosphors, with YAG:Ce, to improve the spectrum output of LB-SSL sources. Electro-thermal circuit simulations assess layer-by-layer (LBL), i.e. series and side-by-side (SBS) or parallel arrangement of red, yellow, and green phosphors using thermal resistance and capacitance, Debye temperature, and time-resolved photoluminescence lifetime. Among the series configurations, the green (GP), yellow (YP), and red (RP) phosphors in sequential order shows wide spectrum. On the other hand, SBS arrangement of the three phosphors exhibits a 40% improvement in color rendering index (CRI, from 65 to 91) and a 37 °C (86 °C to 49 °C) decreased steady-state temperaturecompared to the single yellow phosphor. The electrical equivalent model reduces the number of trials required for testing layered combinations, resulting in a 38% improved spectral width from 97 nm for red-green-yellow to 134 nm for green-yellow-red. These findings enhanced the thermal dissipation and color quality of laser-based lighting systems by identifying the optimal combinations and arrangements of phosphors, making them more energy-efficient for eye-safe visible light communication applications.