Ultra-broadband near-infrared phosphor La2CaTa Zr(1-)O6:Cr3+ for phosphor-converted light-emitting diodes

Broadband near-infrared (NIR) phosphors are key materials for the preparation of NIR phosphor-converted light-emitting diodes (pc-LEDs). The wider coverage of the NIR spectrum means that more substances can be detected by NIR light and more applications are possible. However, ultra-broadband NIR phosphors with the full-width at half maximum (FWHM) greater than 200 nm still face challenges in terms of thermal stability as well as internal quantum efficiency (IQE). In this work, a series of La2CaTaxZr(1-x)O6(LCTZO): Cr3+ phosphors was successfully synthesized by the high-temperature solid-phase method. The non-equivalent substitution strategy of Ta5+ in place of Zr4+ effectively modulates the crystal field environment of Cr3+ and reduces the number of defects, thus modulating the luminescence properties of the phosphor. Under the 471 nm excitation, the spectrum of La2CaTa0.3Zr0.7O6: 2 % Cr3+ can cover the 700–1400 nm band (FWHM = 201 nm) with IQE of 42.6 %, and the emission intensity can be maintained at 373 K at 74 % of that at room temperature. The prepared NIR pc-LED with ultra-wide spectral coverage shows better potential applications in the fields of night vision and biological tissue penetration.