Wide Range Near‐Zero Thermal Quenching of Orange–Yellow Phosphor via Impeding Self‐Oxidation of Eu ²⁺ for Versatile Optoelectronic Applications

Li₂SrSiO₄:Eu²⁺ is a promising substitute for traditional Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce³⁺) owing to its strong orange-yellow emission of 4f-5d transition originating from Eu²⁺ dopant, covering the more red-light region. However, its inevitable luminescence thermal quenching at high temperatures and the self-oxidation of Eu²⁺ strongly impede their applications. Their remediation remains highly challenging. Herein, an anti-self-oxidation(ASO) concept of Eu²⁺ in Li₂SrSiO₄ substrate by adding trivalent rare-earth ions (A³⁺: A = La, Gd, Y, Lu) for highly efficient and stable orange-yellow light emission have been proposed. A significantly increased orange-yellow emission (202% improvement) from Li₂Sr_0.95A_0.05SiO₄:Eu²⁺ with a wide range near-zero thermal quenching is obtained, superior to other Eu²⁺ activated phosphors. The presence of A³⁺ ions with various radii modifies the ASO degree of Eu²⁺ ions, achieving the tunable chemical state, composition, electronic configuration, crystal-field strength, and luminescent characteristics of the developed phosphors. For the proof of the concept, a W-LED device and a PDMS (Polydimethylsiloxane) luminescent film are fabricated, endowing excellent luminescence performance and thermal stability and the huge application prospects of Li₂SrSiO₄:Eu²⁺ in lighting and display fields.