A Strong Red‐Emitting Phosphor‐in‐BASK‐Glass through Spark Plasma Sintering: Insights into the Role of Interfacial Reaction on PL Efficiencies

Abstract Red‐emitting phosphor‐in‐glass (Red‐PiG) color converters are critical for high‐power light‐emitting diode or laser‐driven lighting applications, yet they remain challenging due to the degradation and interfacial reactions of red‐emitting phosphors within glass matrixes. This study investigates the efficacy of spark plasma sintering (SPS) in inhibiting these interfacial reactions across different phosphor and glass compositions. CaAlSiN 3 :Eu 2+ and Sr 2 Si 5 N 8 :Eu 2+ phosphors, along with fluoride and borosilicate glasses, are selected to explore their interfacial behavior during SPS. By optimizing the interfacial morphology, a borosilicate‐based PiG with a luminous flux of 248 lm and a luminous efficiency of 173 lm W −1 is achieved, setting new benchmarks for Red‐PiG performance. In addition, laser‐driven white lighting based on the high‐performance Red‐PiG has a color rendering index of up to 90. The findings elucidate the mechanisms by which SPS can enhance interfacial stability and optical performance in Red‐PiG materials, offering strategic insights for advancing the synthesis of high‐quality PiG materials for optoelectronic applications.