Study on the near-infrared luminescence properties of Cr3+-Yb3+ co-doped Sr2MgWO6 double-perovskite phosphors

A new double-perovskite structured phosphor, Sr 2 MgWO 6 : xCr 3+ , yYb 3+ , with device potential has been successfully synthesized. • The phosphor exhibits emission performance covering the NIR-I to NIR-II regions, with a wavelength range exceeding 400 nm. • This phosphor exhibits excellent thermal stability, and the optical temperature-sensing performance was investigated using FIR. • The phosphor exhibits a Cr 3+ -Yb 3+ energy transfer efficiency (η ET ) exceeding 50%. Near-infrared (NIR) phosphors have shown great potential for applications in temperature sensing, night vision surveillance, agricultural illumination, and so on. In this study, a series of Sr 2 MgWO 6 (SMW): xCr 3+ , yYb 3+ phosphors were synthesized via a conventional high-temperature solid-state reaction method. Firstly, the effects of Mg 2+ content variation on the luminescent properties of Cr 3+ singly doped phosphors were systematically investigated. It was found that the quantum efficiency of the samples reached a maximum when the Mg 2+ content was 120% of the stoichiometric ratio, attributed to the optimization of local crystal field environment around Cr 3+ ions. On this basis, Cr 3+ -Yb 3+ co-doped phosphors were further optimized by introducing Yb 3+ ions, and the optimal composition was determined to be SMW: 0.5% Cr 3+ , 1.5% Yb 3+ . Under 360 nm excitation, the optimized phosphor exhibited intense NIR emission covering the wavelength range of 713-1137 nm. Benefiting from an exceptionally efficient Cr 3+ →Yb 3+ energy transfer (η ET  = 50.18%) achieved at a low Yb 3+ concentration of only 3.0%, the optimized phosphor exhibits a significantly broadened emission bandwidth and enhanced NIR output intensity. Furthermore, the thermal stability of the optimal sample was evaluated by temperature-dependent emission spectra. The results revealed excellent luminescence stability of the phosphor at elevated temperatures. Notably, based on the fluorescence intensity ratio (FIR) between Cr 3+ and Yb 3+ emissions extracted from the variable-temperature spectra, a self-referencing optical temperature sensor was constructed. The absolute and relative sensitivities were calculated, demonstrating the feasibility of the developed phosphor for non-contact temperature sensing applications. Additionally, performance tests on pc-LEDs confirmed their excellent spectral stability, indicating the material's potential for practical applications in NIR pc-LEDs. This work provides a promising strategy for designing broadband NIR-emitting phosphors with dual functionalities of lighting and temperature sensing. Download: Download high-res image (255KB) Download: Download full-size image