A broadband near-infrared phosphor BaZrGe3O9:Cr3+: luminescence and application for light-emitting diodes

Abstract

Recently, near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have attracted considerable interest in the research field worldwide. As the key material, broadband NIR phosphors have become a research hotspot. Herein, a series of Cr³⁺-doped BaZrGe₃O₉ phosphors were successfully designed via nonequivalent substitution. The phosphors exhibited a broadband emission extending from 700 nm to 1200 nm (FWHM = 159 nm) with a maximum of ∼830 nm in the first biological window. To optimize the luminescence properties, the relationships between the doping concentration and crystal structure, luminescence spectra, decay curves were discussed. More importantly, the crystal field parameters D_q, B and Huang–Rhys factor were calculated, and the results may provide insight into factors determining and modifying the luminescence properties of the materials. The persistent luminescence of Cr³⁺ could also be realized, and the luminescence mechanism was proposed. Moreover, a pc-LED prototype was fabricated by combining the BaZrGe₃O₉:Cr³⁺ phosphor with a blue LED chip, and the potential application for broadband NIR pc-LEDs was discussed.