Effective long-term storage and repeatable mechanoluminescence of piezoelectrics LiNbO3:1%Pr3+, 0.5%Zn2+

In this study, we investigated a novel multifunctional piezoelectric phosphor LiNbO 3 :1%Pr 3+ , 0.5%Zn 2+ , which exhibited outstanding mechanoluminescence (ML) characteristics due to the strategic incorporation of Zn 2+ . A dual-regulation mechanism is proposed by adjusting the charge transfer band (CTB) energy level position and optimizing the defect distribution, thus realizing high-brightness, long-term storage, and highly repeatable red emission in ML. The addition of Zn 2+ can lower the CTB energy level of the phosphor, which leads to the easier transfer of 3 P 0 electrons of Pr 3+ to the 1 D 2 energy level through the CTB band, thus enhancing the ML red emission. The introduction of a small amount of Zn 2+ effectively couple the trap structure with the piezoelectric properties of the material, significantly enhancing ML properties. Notably, the material exhibits excellent ML repeatability and long-term storage, maintaining a strong ML response even after 30 d. Density functional theory calculations of the phosphor confirmed that the doping of Zn 2+ in LiNbO 3 :1%Pr 3+ optimized the trap concentration and distribution, thereby improving the ML performance. This multifunctional material holds great potential for use in electromechanical and optoelectronic devices, contributing to the development of smart devices with broader applications. • Introduction of trace Zn 2+ ions effectively regulates the trap distribution in LiNbO 3 . • Lowering the CTB energy level enables easier transfer of Pr 3+ 3 P 0 electrons to 1 D 2 via CTB, boosting the ML red emission. • LNP:1%Pr 3+ ,0.5%Zn shows long-term ML storage, maintaining visible emission after 30 d in darkness without re-excitation. • LNP:1%Pr 3+ , 0.5%Zn maintains strong mechanoluminescence after 50 loading cycles without UV or sunlight re-excitation. • LNP: 1%Pr 3+ , 0.5%Zn shows high ML repeatability as intensity fully recovers after multiple UV or sunlight cycles.