Metal–Organic Framework Luminescence in the Yellow Gap by Codoping of the Homoleptic Imidazolate ∞ 3[Ba(Im)2] with Divalent Europium
The rare case of a metal-triggered broad-band yellow emitter among inorganic–organic hybrid materials was achieved by in situ codoping of the novel imidazolate metal–organic framework ∞ 3[Ba(Im)2] with divalent europium. The emission maximum of this dense framework is in the center of the yellow gap...
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Veröffentlicht in: | Journal of the American Chemical Society 2013-05, Vol.135 (18), p.6896-6902 |
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Hauptverfasser: | , , , , , , , , , , , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The rare case of a metal-triggered broad-band yellow emitter among inorganic–organic hybrid materials was achieved by in situ codoping of the novel imidazolate metal–organic framework ∞ 3[Ba(Im)2] with divalent europium. The emission maximum of this dense framework is in the center of the yellow gap of primary light-emitting diode phosphors. Up to 20% Eu2+ can be added to replace Ba2+ as connectivity centers without causing observable phase segregation. High-resolution energy-dispersive X-ray spectroscopy showed that incorporation of even 30% Eu2+ is possible on an atomic level, with 2–10% Eu2+ giving the peak quantum efficiency (QE = 0.32). The yellow emission can be triggered by two processes: direct excitation of Eu2+ and an antenna effect of the imidazolate linkers. The emission is fully europium-centered, involving 5d → 4f transitions, and depends on the imidazolate surroundings of the metal ions. The framework can be obtained by a solvent-free in situ approach starting from barium metal, europium metal, and a melt of imidazole in a redox reaction. Better homogeneity for the distribution of the luminescence centers was achieved by utilizing the hydrides BaH2 and EuH2 instead of the metals. |
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ISSN: | 0002-7863 1520-5126 |
DOI: | 10.1021/ja3121718 |