Research

11 pages, 3635 KiB

Open AccessArticle

KMnF₃:Yb³⁺,Er³⁺ Core-Active-Shell Nanoparticles with Broadband Down-Shifting Luminescence at 1.5 μm for Polymer-Based Waveguide Amplifiers

by Yongling Zhang, Peng Lv, Dongxia Wang, Zhengkun Qin, Fei Wang, Daming Zhang, Dan Zhao, Guanshi Qin and Weiping Qin

Nanomaterials 2019, 9(3), 463; https://doi.org/10.3390/nano9030463 - 20 Mar 2019

Cited by 10 | Viewed by 3470

Abstract

In this study, we prepared cubic-phase oleic-acid-coated KMnF₃: Yb³⁺,Er³⁺ nanoparticles (NPs) and NaYF₄:Yb³⁺,Er³⁺ NPs, which were about 23 nm. From the down-shifting emissions spectra of the two NPs obtained by 980 nm excitation, [...] Read more.

In this study, we prepared cubic-phase oleic-acid-coated KMnF₃: Yb³⁺,Er³⁺ nanoparticles (NPs) and NaYF₄:Yb³⁺,Er³⁺ NPs, which were about 23 nm. From the down-shifting emissions spectra of the two NPs obtained by 980 nm excitation, we observed the fact that the KMnF₃: 18%Yb³⁺,1%Er³⁺ NPs were a luminescent material with a broadband near-infrared emission of 1.5 μm, and full-width at half-maximum (FWHM) of 55 cm⁻¹, which was wider than that of the NaYF₄: 18%Yb³⁺,1% NPs. Therefore, we believe that the oleic-acid-coated KMnF₃:Yb³⁺,Er³⁺ NPs have great potential in fabricating broadband waveguide amplifiers. Through epitaxial growth of a KMnF₃: Yb³⁺ active-shell on the core NPs, we compounded KMnF₃:Yb³⁺,Er³⁺@KMnF₃:Yb³⁺ core-active-shell NPs whose 1.5-μm infrared emissions intensity was 3.4 times as strong as that of the core NPs. In addition, we manufactured waveguide amplifiers using KMnF₃:18%Yb³⁺,1%Er³⁺@KMnF₃:2%Yb³⁺ NPs as the core materials of the waveguide amplifiers. When the input signal power was 0.2 mW and the pump power was 200 mW, we achieved a relative gain of 0.6 dB at 1534 nm in a 10-mm long waveguide. Full article

(This article belongs to the Special Issue Nanosized Luminescent Materials: Advances and Applications)

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19 pages, 8153 KiB

Open AccessArticle

Facile Synthesis of Ternary Alloy of CdSe_1-xS_x Quantum Dots with Tunable Absorption and Emission of Visible Light

by S. Wageh, Ahmed Al-Ghamdi, Asim Jilani and Javed Iqbal

Nanomaterials 2018, 8(12), 979; https://doi.org/10.3390/nano8120979 - 27 Nov 2018

Cited by 14 | Viewed by 3299

Abstract

The synthesis of alloyed semiconductor quantum dots has produced structures that have distinct properties in comparison with both their bulk counterparts and their parent binary semiconductor quantum dots. In this work, the quantum confined structures of a ternary alloy of CdSe_1−x [...] Read more.

The synthesis of alloyed semiconductor quantum dots has produced structures that have distinct properties in comparison with both their bulk counterparts and their parent binary semiconductor quantum dots. In this work, the quantum confined structures of a ternary alloy of CdSe_1−xS_x were synthesized by one-pot synthesis method in an aqueous medium at a low temperature and capped with 3-mercaptopropoionic acid. Structures of the synthesized quantum dots were investigated by energy dispersive X-ray, X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The obtained quantum dots had modified cubic structures as proven by X-ray diffraction and selected area electron diffraction. The optical properties of the synthesized quantum dots were characterized by optical absorption, photoluminescence, and color analysis. Optical absorption investigation revealed a widening of the band gap of CdSe_1−xS_x with increasing S content. This widening increased for the samples suspended in water relative to the samples measured in powder form due to the difference in the environment of the two cases. The size determined from the optical absorption measurements was found to be compatible with the sizes obtained from the X-ray diffraction with the value of bowing parameter around 1, which indicated a graded diffusion of sulfur. It was also ascertained that the emission of different compositions covered the most visible range with a small full width at half maximum. The x and y values of the chromaticity coordinates decreased with increasing sulfur content of up to 15%, while the z value increased. Full article

(This article belongs to the Special Issue Nanosized Luminescent Materials: Advances and Applications)

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12 pages, 2293 KiB

Open AccessArticle

Aggregation-Induced Emission of Tetraphenylethene-Conjugated Phenanthrene Derivatives and Their Bio-Imaging Applications

by Duy Khuong Mai, Joomin Lee, Ilgi Min, Temmy Pegarro Vales, Kyong-Hoon Choi, Bong Joo Park, Sung Cho and Ho-Joong Kim

Nanomaterials 2018, 8(9), 728; https://doi.org/10.3390/nano8090728 - 15 Sep 2018

Cited by 17 | Viewed by 5884

Abstract

In this study, a series of rationally designed emissive phenanthrene derivatives were synthesized and their aggregation-induced emission (AIE) properties in tetrahydrofuran (THF)/water mixtures were investigated. Two tetraphenylethene (TPE) segments were conjugated to both ends of the phenanthrene core at the para-positions and [...] Read more.

In this study, a series of rationally designed emissive phenanthrene derivatives were synthesized and their aggregation-induced emission (AIE) properties in tetrahydrofuran (THF)/water mixtures were investigated. Two tetraphenylethene (TPE) segments were conjugated to both ends of the phenanthrene core at the para-positions and meta-positions, resulting in pTPEP and mTPEP derivatives, respectively. While the TPE-conjugated phenanthrene derivatives did not show any emission when dissolved in pure THF, they showed strong sky-blue emissions in water-THF mixtures, which is attributed to the restriction of intramolecular motions of TPE segments by aggregation. Furthermore, silica nanoparticles loaded with these AIE-active compounds were prepared and proved to be promising intracellular imaging agents. Full article

(This article belongs to the Special Issue Nanosized Luminescent Materials: Advances and Applications)

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12 pages, 3025 KiB

Open AccessArticle

Gold Rod-Polyethylene Glycol-Carbon Dot Nanohybrids as Phototheranostic Probes

by Yuefang Niu, Guo Ling, Li Wang, Shanyue Guan, Zheng Xie, Eran A. Barnoy, Shuyun Zhou and Dror Fixler

Nanomaterials 2018, 8(9), 706; https://doi.org/10.3390/nano8090706 - 10 Sep 2018

Cited by 9 | Viewed by 4267

Abstract

Emphasis using phototheranostics has been placed on the construction of multifunctional nanoplatforms for simultaneous tumor diagnosis and therapy. Herein, we put forth a novel nanosized luminescent material using the incorporation of red emissive carbon dots on gold nanorods through polyethylene glycol as a [...] Read more.

Emphasis using phototheranostics has been placed on the construction of multifunctional nanoplatforms for simultaneous tumor diagnosis and therapy. Herein, we put forth a novel nanosized luminescent material using the incorporation of red emissive carbon dots on gold nanorods through polyethylene glycol as a covalent linkage for dual-modal imaging and photothermal therapy. The novel nanohybrids, not only retain the optical properties of the gold nanorod and carbon dots, but also possess superior imaging performance in both confocal laser scanning microscopy and fluorescence lifetime imaging microscopy. The nanohybrids also exhibit excellent photothermal performance as phototheranostic nanohybrid probes for in vitro assays. This study promises a new multifunctional nanoplatform for cancer diagnostics and therapeutics. Full article

(This article belongs to the Special Issue Nanosized Luminescent Materials: Advances and Applications)

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11 pages, 2235 KiB

Open AccessArticle

Synthesis of Small Ce³⁺-Er³⁺-Yb³⁺ Tri-Doped BaLuF₅ Active-Core-Active-Shell-Active-Shell Nanoparticles with Strong Down Conversion Luminescence at 1.5 μm

by Yongling Zhang, Yudi Shi, Zhengkun Qin, Mingxing Song and Weiping Qin

Nanomaterials 2018, 8(8), 615; https://doi.org/10.3390/nano8080615 - 14 Aug 2018

Cited by 5 | Viewed by 4077

Abstract

Small fluoride nanoparticles (NPs) with strong down-conversion (DC) luminescence at 1.5 μm are quite desirable for optical fiber communication systems. Nevertheless, a problem exists regarding how to synthesize small fluoride NPs with strong DC emission at 1.5 μm. Herein, we propose an approach [...] Read more.

Small fluoride nanoparticles (NPs) with strong down-conversion (DC) luminescence at 1.5 μm are quite desirable for optical fiber communication systems. Nevertheless, a problem exists regarding how to synthesize small fluoride NPs with strong DC emission at 1.5 μm. Herein, we propose an approach to improve 1.5 μm emission of BaLuF₅:Yb³⁺,Er³⁺ NPs by way of combining doping Ce³⁺ ions and coating multiple BaLuF₅: Yb³⁺ active-shells. We prepared the BaLuF₅:18%Yb³⁺,2%Er³⁺,2%Ce³⁺ NPs through a high-boiling solvent method. The effect of Ce³⁺ concentration on the DC luminescence was systematically investigated in the BaLuF₅:Yb³⁺,Er³⁺ NPs. Under a 980 nm laser excitation, the intensities of 1.53 μm emission of BaLuF₅:18%Yb³⁺,2%Er³⁺,2%Ce³⁺ NPs was enhanced by 2.6 times comparing to that of BaLuF₅:18%Yb³⁺,2%Er³⁺ NPs since the energy transfer between Er³⁺ and Ce³⁺ ions: Er³⁺:⁴I_11/2 (Er³⁺) + ²F_5/2 (Ce³⁺) → ⁴I_13/2 (Er³⁺) + ²F_7/2 (Ce³⁺). Then, we synthesized BaLuF₅:18%Yb³⁺,2%Er³⁺,2%Ce³⁺@BaLuF₅:5%Yb³⁺@BaLuF₅:5%Yb³⁺ core-active-shell-active-shell NPs via a layer-by-layer strategy. After coating two BaLuF₅:Yb³⁺ active-shell around BaLuF₅:Yb³⁺,Er³⁺,Ce³⁺ NPs, the intensities of the 1.53 μm emission was enhanced by 44 times compared to that of BaLuF₅:Yb³⁺,Er³⁺ core NPs, since the active-shells could be used to not only suppress surface quenching but also to transfer the pump light to the core region efficiently through Yb³⁺ ions inside the active-shells. Full article

(This article belongs to the Special Issue Nanosized Luminescent Materials: Advances and Applications)

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6 pages, 2965 KiB

Open AccessCommunication

Functional Group Effects on the HOMO–LUMO Gap of g-C₃N₄

by Hao Li, Zhien Zhang, Yulu Liu, Wanglai Cen and Xubiao Luo

Nanomaterials 2018, 8(8), 589; https://doi.org/10.3390/nano8080589 - 03 Aug 2018

Cited by 48 | Viewed by 8327

Abstract

Graphitic carbon nitride (g-C₃N₄) is a promising semiconductor material which has been widely studied in nanoscience. However, the effect of modifying the performance of g-C₃N₄ is still under debate. In this communication, we show the size [...] Read more.

Graphitic carbon nitride (g-C₃N₄) is a promising semiconductor material which has been widely studied in nanoscience. However, the effect of modifying the performance of g-C₃N₄ is still under debate. In this communication, we show the size and functional group effects on the g-C₃N₄ using density functional theory (DFT) calculations. It was found that a molecule with six repeated g-C₃N₄ units (g-C₃N₄-6) could be the smallest unit that converges to the limit of its HOMO–LUMO gap. Calculations of g-C₃N₄-6 with varying numbers of substituted C≡N, C=O, and O−H functional groups show that C≡N and C=O could narrow down the HOMO–LUMO gap, while O−H could slightly raise the gap. This study shows that the change of substituents could tune the band gap of g-C₃N₄, suggesting that rationally modifying the substituent at the edge of g-C₃N₄-based materials could help to significantly increase the photocatalytic properties of a metal-free g-C₃N₄. Full article

(This article belongs to the Special Issue Nanosized Luminescent Materials: Advances and Applications)

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11 pages, 1697 KiB

Open AccessArticle

Efficient Blue to Red Afterglow Tuning in a Binary Nanocomposite Plastic Film

by Yan Xia, Huase Ou, Wanbin Li, Gang Han and Zhanjun Li

Nanomaterials 2018, 8(4), 260; https://doi.org/10.3390/nano8040260 - 20 Apr 2018

Cited by 11 | Viewed by 4455

Abstract

Colorful spectra are important for the diverse applications of persistent phosphors. A color conversion concept is developed to obtain abundant persistent luminescence color by mining capacities of known persistent phosphors with the most efficient persistent properties. Here, SiO₂/Sr₂MgSi₂ [...] Read more.

Colorful spectra are important for the diverse applications of persistent phosphors. A color conversion concept is developed to obtain abundant persistent luminescence color by mining capacities of known persistent phosphors with the most efficient persistent properties. Here, SiO₂/Sr₂MgSi₂O₇:Eu,Dy nanoparticles are chosen as a blue persistent luminescence donor nanophosphor, while ultrafine CaAlSiN₃:Eu is utilized as a red conversion phosphor to tune the persistent luminescence spectra from blue to red. The red afterglow emission can persist for more than 5 h. The decay of the red afterglow follows nearly the same kinetics as that of the blue one. Continuous color tuning can be successfully obtained by simply changing the mass ratio of the donor/conversion phosphor pair. This color conversion strategy may be significant in indicating numerous persistent/conversion nanocomposites or nanostructures and advance the development of persistent phosphors in diverse fields which need colorful spectral properties. Full article

(This article belongs to the Special Issue Nanosized Luminescent Materials: Advances and Applications)

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13 pages, 2800 KiB

Open AccessArticle

Effect of the Composition of Lanthanide Complexes on Their Luminescence Enhancement by Ag@SiO₂ Core-Shell Nanoparticles

by Xiao-Jing Wang, Yan-Rong Qu, Yong-Liang Zhao and Hai-Bin Chu

Nanomaterials 2018, 8(2), 98; https://doi.org/10.3390/nano8020098 - 09 Feb 2018

Cited by 21 | Viewed by 4845

Abstract

Metal-enhanced luminescence of lanthanide complexes by noble metal nanoparticles has attracted much attention because of its high efficiency in improving the luminescent properties of lanthanide ions. Herein, nine kinds of europium and terbium complexes—RE(TPTZ)(ampca)₃·3H₂O, RE(TPTZ)(BA)₃·3H₂O, [...] Read more.

Metal-enhanced luminescence of lanthanide complexes by noble metal nanoparticles has attracted much attention because of its high efficiency in improving the luminescent properties of lanthanide ions. Herein, nine kinds of europium and terbium complexes—RE(TPTZ)(ampca)₃·3H₂O, RE(TPTZ)(BA)₃·3H₂O, RE(phen)(ampca)₃·3H₂O, RE(phen)(PTA)_1.5·3H₂O (RE = Eu, Tb) and Eu(phen)(BA)₃·3H₂O (TPTZ = 2,4,6-tri(2-pyridyl)-s-triazine, ampca = 3-aminopyrazine-2-carboxylic acid, BA = benzoic acid, phen = 1,10-phenanthroline, PTA = phthalic acid)—have been synthesized. Meanwhile, seven kinds of core-shell Ag@SiO₂ nanoparticles of two different core sizes (80–100 nm and 40–60 nm) and varied shell thicknesses (5, 12, 20, 30 and 40 nm) have been prepared. The combination of these nine types of lanthanide complexes and seven kinds of Ag@SiO₂ nanoparticles provides an opportunity for a thorough investigation of the metal-enhanced luminescence effect. Luminescence spectra analysis showed that the luminescence enhancement factor not only depends on the size of the Ag@SiO₂ nanoparticles, but also strongly relates to the composition of the lanthanide complexes. Terbium complexes typically possess higher enhancement factors than their corresponding europium complexes with the same ligands, which may result from better spectral overlap between the emission bands of Tb complexes and surface plasmon resonance (SPR) absorption bands of Ag@SiO₂. For the complexes with the same lanthanide ion but varied ligands, the complexes with high enhancement factors are typically those with excitation wavelengths located nearby the SPR absorption bands of Ag@SiO₂ nanoparticles. These findings suggest a combinatorial chemistry strategy is necessary to obtain an optimal metal-enhanced luminescence effect for lanthanide complexes. Full article

(This article belongs to the Special Issue Nanosized Luminescent Materials: Advances and Applications)

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