Pressure-Engineered Trap-Controlled Multimodal Luminescence for Versatile Emission Responses in Pr-doped NaNbO3

Abstract

Multimodal luminescent (MML) materials have attracted significant attention in anti-counterfeiting applications due to their high sensitivity, concealability, and compatibility. However, limited understanding of their mechanisms hinders rational material design and further advancement. Herein, we report that NaNbO3: Pr3+ phosphors, synthesized via solid-state reaction, exhibit distinctive pressure-responsive MML behaviors, encompassing photoluminescence (PL), persistent luminescence (PersL), and mechanoluminescence (ML). Under UV irradiation at increasing pressure, the PL intensity exhibits a volcano-shaped trend, peaking at approximately 4.5 GPa. After the irradiation is terminated, both the PersL intensity and decay time remain nearly unchanged. Conversely, the ML intensity decreases exponentially with pressure and becomes almost completely quenched around 4.0 GPa. In situ high-pressure structural and spectroscopic analyses indicate that the distinctive MML phenomena likely arise from the different pressure sensitivities of the coordination environments associated with deep traps and shallow traps, which offers insights into the underlying mechanism of MML materials. Furthermore, the integration of multiple luminescence modes enables rich and tunable emission responses, paving the way for advanced stress-sensing platforms and high-security anti-counterfeiting technologies.