Synthesis of luminescent terbium-thenoyltriflouroacetone MOF nanorods for green laser application

• Published in: Optical materials Vol. 87; pp. 3 - 10
• Main Authors: Medina-Velazquez, D.Y., Caldiño, U., Morales-Ramirez, A., Reyes-Miranda, J., Lopez, R.E., Escudero, R., Ruiz-Guerrero, R., Morales Perez, M.F.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-01-2019
• Subjects: Green emission; Green laser; Luminescence; Luminescent MOF; Metalorganic framework; Rod-like morphology; Green emission; Rod-like morphology; Green laser; Luminescent MOF; Luminescence; Metalorganic framework
• DOI: 10.1016/j.optmat.2018.08.021
• EISSN: 1873-1252
• ISSN: 0925-3467

The metalorganic frameworks (MOFs) with lanthanides ions offer great potential in the optical area because can provide properties of flexibility, low density, low-cost methods of synthesis, and insolubility in water, which give them an advantage over traditional phosphors. In this study, a thenoyltriflouroacetone ligand (TTA) with a Tb3+ MOF was synthesized (Tb = 10 and 50% mol) and its structural and luminescent properties were analyzed. The metalorganic compound was generated in a simple one-pot reaction from terbium nitrate and 2-thenoyltrifluoroacetone precursors at room temperature. By means of FTIR, it was confirmed the presence of carbon groups, which made possible the terbium ion chelation, and also the Tb-O bonds vibration modes. 1HNMR results confirm that the complex with 10% mol of Tb3+ contains three coordinates molecules of TTA and two waters molecules. The powders exhibit rod-like morphology with size about 170 nm of diameter and a length about 2 μm; the rod-like nature of powders was confirmed by SEM and TEM analyses. By XRD it was concluded that at higher terbium concentration (TTA-50Tb sample) higher the crystallite size and crystallinity, in fact the TTA-10Tb sample shows a partial-amorphous nature. By photoluminescence analyses, the 5D4→7FJ (J = 3, 4, 5 and 6) emissions were recorded for both synthesized samples (λexc = 376 nm). Furthermore, it was observed that the emission intensity was enhanced in a factor of 3.5 for the TTA-50Tb. The energy transfer efficiency from TTA to Tb3+ (antenna effect) was 0.984 for TTA-10Tb and 0.993 for TTA-50Tb. Decay time analyses indicate effective lifetime of 1.45 and 1.60 m s for the samples doped at 10 and 50%, respectively, indicating that the forbidden transition rules are stronger at higher crystallinity. The integrated intensities of the 5D4→7F5 (green at 541 nm) and 5D4→7F6 (blue at 486 nm) emissions and their intensity ratios IG/IB upon 376 nm excitation have been evaluated for TTA-10Tb andTTA-50Tb samples. The CIE1931 color of the MOFs excited at 376 nm attains a higher green color purity by increasing the terbium concentration. This is in concordance with the increased IG/IB ratio up for the TTA-10Tb and TTA-50Tb samples. Thus, the TTA-50Tb sample exhibits a green color purity of 67.94% with chromaticity coordinates (0.30, 0.57), being very close to those (0.29, 0.60) of European Broadcasting Union illuminant green. This interesting feature of the TTA-50Tb sample, together with an experimental branching ratio of 61.3% for the 5D4 → 7F5 green emission, highlights its capability as solid state green laser pumped by GaN (376 nm) LEDs.
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•An metalorganic luminescent material was generated in a one-pot reaction from terbium nitrate and 2-thenoyltrifluoroacetone at room temperature with rod-like morphology and highly crystalline.•Efficient energy transfer from TTA ligand to Terbium was confirmed, with an efficiency of 0.984 and 0.993 for TTA-10Tb and TTA-50Tb.•The TTA-50Tb sample exhibit a green color purity of 67.9% with CIE coordinates (0.306, 0.574) close to the (0.29, 0.60) of European Broadcasting Union illuminant green.•Those interesting features described before, their capability as solid state green lasers pumped by GaN (376 nm) LEDs were measured.