Tunable broadband near-infrared photoluminescence of Mg2LaTaO6:Cr3+ phosphors for light-emitting diodes

Abstract

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LED) prepared with near-infrared (NIR) phosphors have potential applications in various aspects. In this paper, Cr3+-activated Mg2LaTaO6 (MLTO: Cr3+) phosphors were prepared by the conventional high-temperature solid-phase method. The structure, morphology, and photoluminescence (PL) spectra of MLTO: Cr3+ phosphor were investigated. There is broadband NIR emission and the emission peak is red-shifted with the increase of doping concentration. The crystal field strengths of the samples were calculated and the relationship between the emission peak positions of the samples and the crystal field strengths was investigated. In addition, the concentration quenching mechanism of the samples was discussed, which is mainly attributed to dipole-dipole interactions. The internal quantum efficiency (IQE) of the MLTO: 0.4 mol% Cr3+ sample was measured with an IQE value of 76.48 %. NIR pc-LED devices were fabricated by combining the prepared MLTO: Cr3+ phosphor and blue-emitting LED chips, which are capable of emitting NIR light.