Designing high thermally stable deep red phosphors based on low thermal expansion coefficients for optical applications

Mn 4+ -activated oxide phosphors with low cost and unique luminescent properties have been considered as a promising candidate for various optical applications, while the search for high thermal stable red-emitting phosphors is still a huge challenge. In our work, we find and unveil the relationship between luminescence thermal quenching behavior and thermal expansion coefficients ( α /10 −6 K −1 ) based on double-perovskite niobate phosphors Ca 2 LnNbO 6 :Mn 4+ (Ln 3+ = Y 3+ , Gd 3+ , La 3+ , or Lu 3+ ). It can be concluded that the phosphors with low thermal expansion coefficients contribute to high thermal stability. Subsequently, Ca 2 LuNbO 6 :Mn 4+ accomplishes accurate temperature testing and high-CRI white light-emitting diodes. Thus, a thermal expansion coefficient strategy is a new guide to select the appropriate substrate with high thermal stability for an Mn 4+ -activated emitter.