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Issue 12, 2018
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The electronic and optical properties of a narrow-band red-emitting nanophosphor K2NaGaF6:Mn4+ for warm white light-emitting diodes

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Abstract

Recently, as a key red component in the development of warm white light-emitting diodes (WLEDs), Mn4+-doped fluorides with narrow red emission have sparked rapidly growing interest because they improve color rendition and enhance the visual energy efficiency. Herein, a red nanophosphor, K2NaGaF6:Mn4+, with a diameter of 150–250 nm has been synthesized using a simple co-precipitation method. Rietveld refinement reveals that it crystallizes in the space group Fm[3 with combining macron]m with the cell parameter a = 8.25320(4) Å. The exchange charge model (ECM) has been used to calculate the energy levels of Mn4+ ions in K2NaGaF6, which match well with the experimental spectra. The as-synthesized phosphor exhibits a narrow red emission at around 630 nm (spin-forbidden 2Eg4A2 transition of Mn4+ ions) when excited at 365 nm (4A2g4T1g) and 467 nm (4A2g4T2g), with a quantum efficiency (QE) of 61% and good resistance to thermal quenching. Based on the structure, the formation mechanism of ZPL has been discussed. In addition, the concentration-dependent decay curves of Mn4+ in K2NaGaF6 were fitted using the Inokuti–Hirayama model, suggesting that the dipole–dipole interactions determine the concentration quenching. Finally, encouraged by the good performance, a warm LED with a CRI of 89.4 and CCT of 3779 K was fabricated by employing the title nanophosphor as the red component. Our findings suggest that K2NaGaF6:Mn4+ can be a viable candidate for the red phosphor used in warm WLEDs.

Graphical abstract: The electronic and optical properties of a narrow-band red-emitting nanophosphor K2NaGaF6:Mn4+ for warm white light-emitting diodes

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Publication details

The article was received on 08 Nov 2017, accepted on 21 Feb 2018 and first published on 22 Feb 2018


Article type: Paper
DOI: 10.1039/C7TC05098D
Citation: J. Mater. Chem. C, 2018,6, 3016-3025
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    The electronic and optical properties of a narrow-band red-emitting nanophosphor K2NaGaF6:Mn4+ for warm white light-emitting diodes

    C. Jiang, M. G. Brik, L. Li, L. Li, J. Peng, J. Wu, M. S. Molokeev, K. Wong and M. Peng, J. Mater. Chem. C, 2018, 6, 3016
    DOI: 10.1039/C7TC05098D

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