Engineering Trap Distribution by Doping Rare Earth Ion for Mechanoluminescence Enhancement

Mechanoluminescence materials exhibit fascinating optical properties due to their energy harvesting and controllable release capabilities. SrAl₂O₄:Eu²⁺ (SAOE) has been extensively studied as a traditional mechanoluminescence material, however, the luminescence intensity enhancement and the luminescence mechanism of its mechanoluminescence remain an unresolved issue, which hinders the development and widespread application of excellent phosphors. Herein, a promising rare earth (Re³⁺ = Sm³⁺, Dy³⁺, Er³⁺, and Tm³⁺) doping strategy was proposed to achieve intense mechanoluminescence of SAOE. By introducing different Re³⁺ ions to manipulate the energy level positions in SAOE phosphors, the depth and density of electron and hole traps can be tuned, resulting in the maximum mechanoluminescence intensity of SrAl₂O₄:Eu²⁺, Tm³⁺ is about 11-fold higher than that of SAOE. The mechanism governing trap distribution has been unveiled through thermoluminescence glow curve analysis and density functional theory calculations. Our research provides valuable guidance for designing high-performance phosphors and opens up new opportunities for multifunctional applications.