Stable and Highly Efficient Near-Infrared Emission Achieved in Spinel Blocks.

Zhang, Xibao; Zhou, Liang; You, Hongpeng · Adv Mater · 2025

basic_science · Level V

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Abstract

Developing efficient and stable near-infrared emitters related to Cr<sup>3+</sup>-pairs for advanced optoelectronic devices remains a challenge due to concentration quenching effects and unclear luminescence mechanisms. In this study, Cr<sup>3+</sup> ions are incorporated into a matrix structure consisting of ZnAl₂O₄ spinel units separated by 11.312 Å, effectively restricting energy transfer between luminescent centers and alleviating quenching effects. Computational analysis identifies the lattice positions of isolated Cr<sup>3+</sup> ions and Cr<sup>3+</sup>-pairs at different doping levels, providing insights into their spatial distribution and local structural environments. Photoluminescence measurements reveals a Cr<sup>3+</sup>-concentration-dependent emission broadening, with a Cr<sup>3+</sup>-pair emission band peak at 750 nm, while detailed spectral analysis further clarified the energy level structure of Cr<sup>3+</sup>-pairs for the first time. Enhanced material performance is achieved through flux-assisted synthesis, reaching a high external quantum efficiency of 58.3%. Consequently, the assembled pc-LEDs exhibit minimal efficiency roll-off and achieve a high output of 183 mW at 650 mA, demonstrating their potential in near-infrared light sources and night vision technology application.