Abstract
AbstractAn important challenge in the research and development of compact near‐infrared (NIR) light sources is the discovery of new efficient ultra‐broadband NIR luminescent materials to replace the conventional Cr3+‐doped compounds. Herein, this work reports a divalent europium‐doped Ba3GeO4Br2 phosphor that exhibits a high photoluminescence quantum yield of 48.8% and an ultra‐broad emission band ranging continuously from 500 to 1100 nm (full width at half maximum = 202 nm) under near‐ultraviolet or blue light excitation. A strategy of embedding alumina crucible in high purity graphite crucible is devised and deployed during solid‐state sintering to facilitate the conversion of Eu3+ into Eu2+. Theoretical calculations, structural refinement, and spectral analysis demonstrate that the visible to NIR emission in Ba3GeO4Br2:Eu2+ originates from the Eu2+ ions occupying the distorted Ba3O3Br4 polyhedra in the lattice. The as‐prepared phosphor‐converted light‐emitting diode device achieves an optical output power of 30.1 mW@100 mA (520–1100 nm) and a photoelectric efficiency of 22%@100 mA (350–1100 nm). Experiments on tissue penetration and NIR imaging illustrate its application in spectral detection and food quality testing appears promising.
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