Novel layered perovskite Sr₃Ti₂O₇:Eu³⁺ phosphor with high-efficiency luminescence enhanced by charge compensation

A novel Sr₃Ti₂O₇:Eu³⁺ red phosphor with double-layered perovskite structure was successfully synthesized by solid-state reaction method using Li⁺ ions as charge compensators. Its crystal structure, morphology and photoluminescence under different calcination temperatures and different compensation styles of Li⁺ were investigated. The phosphor could obtain pure tetragonal perovskite phase with I4/mmm space group at 1300 °C. Non-stoichiometric (NSC) compensation could keep more Sr²⁺ ions to hold the perovskite structure stable for higher doping concentration of Eu³⁺. The emission was dominated by the electric-dipole transition with obvious peak splitting due to two different doping sites with lower symmetry of Sr²⁺. Layered structure provided bigger space to hold more Li⁺ ions and NSC style had bigger advantage on the luminescence enhancement for higher doping concentration. Better excitation matches, higher quantum yield (25.1%, λ_ex = 395 nm) and better color rendering properties provided a potential red material for white LEDs.