Long-wavelength near-infrared light emitting Ni2+-doped double perovskite molybdate-based solid-solution phosphors

Abstract

Long wavelength near-infrared (LWNIR) light (1000–2000 nm) has great potential in the field of biomedical imaging, non-visual illumination, and non-destructive detection. However, currently, such as Cr³⁺ and Ni²⁺ can achieve broadband NIR emission, but their emission wavelengths are under 1600 nm with limited tunability. Herein, we developed Ni²⁺-doped (Sr/Ba)₂MgMoO₆ double perovskite molybdate-based solid-solution LWNIR phosphors via the high-temperature solid-state method. By adjusting the ratio of Sr/Ba in the phosphors, NIR emission peaks can be tuned from 1400 nm to 1610 nm under 400 nm excitation. Based on the analysis of crystal structures and luminescence characteristics and simulation results, we propose that the main reason for the shift of NIR peak emission is the difference in charge density and symmetrical polarizability of Ni²⁺ ions in the center of the octahedron due to the crystal structural changes of the matrices from tetragonal Sr₂MgMoO₆ to cubic phase Ba₂MgMoO₆. We constructed a LWNIR pc-LED with the optimal phosphors and a commercially near-ultraviolet LED chip, which efficiently emitted LWNIR light. The utility of this new LWNIR pc-LED as the NIR light source for non-invasive imaging and non-destructive detection of biological and non-biological objects was demonstrated.