Deep-red to NIR mechanoluminescence in centrosymmetric perovskite MgGeO3: Mn2+ for potential dynamic signature anti-counterfeiting

Abstract

Developing deep-red to near infrared (NIR) materials with multi-mode luminescence is challenging, which has promising utilization in various applications such as stress sensing and dynamic signature anti-counterfeiting. Different to the mainstream non-centrosymmetric mechanoluminescence (ML), a centrosymmetric perovskite compound (MgGeO3: Mn2+) ML material is reported. Deep-red to NIR light (600–800 nm) from Mn2+ ion is confirmed, which is attributed to the strong crystal field within the [MgO6] polyhedron. The stiffness tetrahedral units and large defect accommodating space within the host are favorable for both ML and persistent luminescence (PersL). Mn2+ ion is the only luminescent center, which is confirmed by spectral characterizations. Based on diffuse reflectance spectra, thermoluminescence analysis and density functional theory calculations, the inherent relationship between PersL, ML and PL is further clarified in detail. Due to the formation of MnMg defects, shallow trap significantly become shallower after adding Mn2+ ions. This study reports a Mn2+-doped deep-red to NIR ML phosphor, and further describes the PersL and ML mechanisms via defect engineering regulation. In general, this study may also open up a new approach for the development of efficient NIR ML materials, and show various potential applications such as in anti-counterfeiting and information encryption fields.