Chromium ion pair luminescence: a strategy in broadband near- infrared light-emitting diode design

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American Chemical Society
Portable near-infrared (NIR) light sources are in high demand for applications in spectroscopy, night vision, bioimaging, and many others. Typical phosphor designs feature isolated Cr3+ ion centers, and it is challenging to design broadband NIR phosphors based on Cr3+–Cr3+ pairs. Here, we explore the solid-solution series SrAl11.88–xGaxO19:0.12Cr3+ (x = 0, 2, 4, 6, 8, 10, and 12) as phosphors featuring Cr3+–Cr3+ pairs and evaluate structure–property relations within the series. We establish the incorporation of Ga within the magentoplumbite-type structure at five distinct crystallographic sites and evaluate the effect of this incorporation on the Cr3+–Cr3+ ion pair proximity. Electron paramagnetic measurements reveal the presence of both isolated Cr3+ and Cr3+–Cr3+ pairs, resulting in NIR luminescence at approximately 650–1050 nm. Unexpectedly, the origin of broadband NIR luminescence with a peak within the range 740–820 nm is related to the Cr3+–Cr3+ ion pair. We demonstrate the application of the SrAl5.88Ga6O19:0.12Cr3+ phosphor, which possesses an internal quantum efficiency of ∼85%, a radiant flux of ∼95 mW, and zero thermal quenching up to 500 K. This work provides a further understanding of spectral shifts in phosphor solid solutions and in particular the application of the magentoplumbites as promising next-generation NIR phosphor host systems. © 2021 American Chemical Society
Phosphors, Luminescence, Sensors, Ions, Chromium ions, Quantum efficiency, Light emitting diodes
Rajendran, V., Fang, M.-H., Huang, W.-T., Majewska, N., Lesniewski, T., Mahlik, S., Leniec, G., Kaczmarek, S. M., Pang, W. K., Peterson, V. K., Lu, K.-M., Chang, H. & Liu, R. S. (2021). Chromium ion pair luminescence: a strategy in broadband near-infrared light-emitting diode design. Journal of the American Chemical Society, 143(45), 19058–19066. doi:10.1021/jacs.1c08334