Energy-transfer enhanced Cr3+/Ni2+ co-doped tantalate phosphors for broadband NIR pc-LED applications

Abstract

Near-infrared (NIR) emitting materials have garnered significant interest for their excellent performance in optical imaging, optical temperature sensing, non-destructive testing, and other fields. This paper presents a near-infrared (NIR) material, Mg₂LaTaO₆ (MLTO):Cr³⁺,Ni²⁺, synthesized using the high-temperature solid-state method. When excited at 468 nm, the material exhibits broadband emission ranging from 700 to 1600 nm with a full width at half maximum (FWHM) of 1232 cm⁻¹. The Cr³⁺ → Ni²⁺ energy transfer (ET) significantly enhances Ni²⁺ emission, increasing its intensity 2.85 times at 1336 nm and the ET efficiency to 79%. The material also demonstrates excellent thermal stability, retaining 87% of its emission intensity at 423 K. By integrating the phosphor with a 460 nm blue light chip, an NIR pc-LED was successfully fabricated, showing potential for applications in medical imaging, information encryption, organic compound identification, and fruit freshness detection. The co-doping strategy of Cr³⁺ and Ni²⁺ effectively solves the issue of Ni²⁺ emission being difficult to excite with blue light, offering a novel design strategy for the development of wideband NIR pc-LEDs based on blue light LED chips.