Suppressing Self‐Oxidation of Eu²⁺ in Li₂CaSiO₄ for Full‐Spectrum Lighting and Accurate Temperature Sensing

Eu 2+ ‐doped phosphors have attracted the great attention of researchers in the past decade. However, Eu 2+ dopant in inorganic hosts often suffers from the self‐oxidation effect, therefore causing the attenuated emission intensity and quantum efficiency. In this regard, developing Eu 2+ doped phosphors with the prohibited self‐oxidation effect of Eu 2+ and increased thermal stability is urgently required. Herein, an innovative cyan‐light emitting Li 2 CaSiO 4 :Eu 2+ /Eu 3+ , Lu 3+ (LCSO) phosphor is designed. Both experimental results and theoretical calculations demonstrate that adding Lu 3+ restricts the self‐oxidation of Eu 2+ into Eu 3+ , thus improving the emission of Eu 2+ . Meanwhile, the Lu 3+ introduction brings out excellent thermal stability. Finally, an efficient WLED with a color temperature (CCT) of 4573 K and a high color rendering index (R a ) of 84.2 is obtained using the as‐prepared phosphor due to the perfect compensation of the cyan light. As the introduction of Lu 3+ improves the stability of Eu 2+ , a much greater difference in PL decay rate between Eu 2+ and Eu 3+ in LCSO is reached, thereby improving their sensitivity in temperature sensing. The strategy of Lu 3+ introduction for prohibiting the self‐oxidation of Eu 2+ for efficient and stable Eu 2+ emission may stimulate some new ideas in designing high‐performance phosphors for more diverse applications.