Near-infrared luminescence regulation and imaging applications of novel Cr3+-doped double-perovskite structured tantalate phosphors

Abstract

Near-infrared (NIR) phosphor-converted light emitting diode (pc-LED) exhibits great application promise in night vision lighting, bioimaging and plant growth fields, etc. However, NIR phosphors still suffer from narrowband emission and low thermal stability. Herein, a series of novel Cr³⁺-doped double-perovskite structured tantalate Ca₂BTaO₆: Cr³⁺ (B = Ga, In, Sc) NIR phosphor with dual luminescence centers were prepared. Benefiting from the tunability of the B-site atom in the crystal structure, the dominant emission peak can be red-shifted from 750 nm to 797 nm and 816 nm through cation substitution from Ga to In system, and the effects of cation substitution on the NIR luminescent properties and thermal stability of the phosphors were investigated in detail. Furthermore, the introduction of additional energy transfer pathways via co-doping with Yb³⁺ also allows for the overall emission spectrum to cover the region between 700 nm to 1150 nm, significantly expanding the full width at half maximum (FWHM) up to 262 nm. Finally, as-prepared Ca₂GaTaO₆: Cr³⁺, Yb³⁺ phosphors were encapsulated to fabricate NIR pc-LED device, achieving a photoelectric conversion efficiency of 4.5% at a driving current as low as 40 mA, demonstrating their potential applications in NIR night vision detection and biological vascular imaging.