Efficient and stable near-infrared Y₂Mg₂Al₂Si₂O₁₂:Cr³⁺ phosphor: analysis of the luminescence source by a site elimination strategy

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) are the ideal light source for next-generation NIR spectroscopy, and developing novel NIR phosphors with high performance is crucial to achieve a wide range of NIR pc-LED applications. In this work, NIR luminescent material Y₂Mg₂Al₂Si₂O₁₂ (YMAS):2%Cr³⁺ with good quantum efficiency (79%) and excellent thermal stability (88%@100 °C) is prepared. Under 430 nm light excitation, YMAS:2%Cr³⁺ emits 620–1100 nm NIR light with a full-width at half maximum (FWHM) of 153 nm. Fluorescence decay curves, photoluminescence (PL) spectra, 7 K PL spectra, the Rietveld refinement, ²⁷Al solid-state nuclear magnetic resonance (ss-NMR) spectra and time-resolved emission spectroscopy (TRS) confirm that Cr³⁺ has two different luminescence centers in the YMAS lattice. Benefiting from the site elimination strategy, the double luminescence centers are proven to be derived from Cr³⁺ ions occupying the two sites [Al₁O₆] and [Al₂O₄]. The NIR packaging device prepared using YMAS:2%Cr³⁺ has outstanding NIR output power and photovoltaic conversion efficiency as high as 45.7 mW@100 mA and 16.7%@100 mA, respectively. Owing to the excellent performance of the YMAS:2%Cr³⁺ sample, it presents excellent practical performance in plant growth, bioimaging, non-destructive testing and night vision.