Defect Driven Emission from ZnO Nano Rods Synthesized by Fast Microwave Irradiation Method for Optoelectronic Applications

2014 ◽  
Vol 1633 ◽  
pp. 75-80 ◽  
Author(s):  
Nagendra Pratap Singh ◽  
S.A. Shivashankar ◽  
Rudra Pratap
Keyword(s):  
Microwave Irradiation ◽  
Zinc Acetate ◽  
Zinc Acetate Dihydrate ◽  
Zno Nanorods ◽  
Life Time ◽  
Minority Carrier Lifetime ◽  
Yellow Emission ◽  
Transmission Microscopy ◽  
Luminescence Efficiency ◽  
Optoelectronic Applications

ABSTRACTBecause of its large direct band gap of 3.37 eV and high exciton binding energy (∼60 meV), which can lead to efficient excitonic emission at room temperature and above, ZnO nanostructures in the würtzite polymorph are an ideal choice for electronic and optoelectronic applications. Some of the important parameters in this regard are free carrier concentration, doping compensation, minority carrier lifetime, and luminescence efficiency, which are directly or indirectly related to the defects that, in turn, depend on the method of synthesis. We report the synthesis of undoped ZnO nanorods through microwave irradiation of an aqueous solution of zinc acetate dehydrate [Zn(CH3COO)2. 2H2O] and KOH, with zinc acetate dihydrate acting as both the precursor to ZnO and as a self-capping agent. Upon exposure of the solution to microwaves in a domestic oven, ZnO nanorods 1.5 µm -3 µm and 80 nm in diameter are formed in minutes. The ZnO structures have been characterised in detail by X-ray diffraction (XRD), selective area electron diffraction (SAED) and high-resolution scanning and transmission microscopy, which reveal that each nanorod is single-crystalline. Optical characteristics of the nanorods were investigated through photoluminescence (PL) and cathodoluminescence (CL). These measurements reveal that defect state-induced emission is prominent, with a broad greenish yellow emission. CL measurements made on a number of individual nanorods at different accelerating voltages for the electrons show CL intensity increases with increasing accelerating voltage. A red shift is observed in the CL spectra as the accelerating voltage is raised, implying that emission due to oxygen vacancies dominates under these conditions and that interstitial sites can be controlled with the accelerating voltage of the electron beam. Time-resolved fluorescence (TRFL) measurements yield a life time (τ) of 9.9 picoseconds, indicating that ZnO nanorods synthesized by the present process are excellent candidates for optoelectronic devices.

Effect of ZnO Seed Layer with Various Concentrations of Precursor on the Growth of ZnO Nanostructures

2016 ◽  
Vol 675-676 ◽  
pp. 237-240
Author(s):  
Nontakoch Siriphongsapak ◽  
Somyod Denchicharoen ◽  
Pichet Limsuwan
Keyword(s):  
Zinc Acetate ◽  
Seed Layer ◽  
Zinc Acetate Dihydrate ◽  
Zno Nanorods ◽  
Crystallographic Structure ◽  
Nitrate Hexahydrate ◽  
X Rays ◽  
Zno Nanostructures ◽  
Acetate Dihydrate ◽  
Seed Layers

In this work, Zinc oxide (ZnO) thin films were deposited on silicon and glass substrates using spin-coating method with different concentrations of precursor (zinc acetate dihydrate) and stabilizer (monoethanolamine). The concentrations of zinc acetate dihydrate and monoethanolamine in isopropanol were varied from 6 mM to 500 mM. Subsequently, the substrate with ZnO thin film as a seed layer was used to grow ZnO nanostructures by hydrothermal process with the same concentration of precursor (zinc nitrate hexahydrate), temperature, and time for each growth. The samples were characterized by field-emission scanning electron microscopy (FESEM), X-rays diffractometer (XRD), and UV-visible spectrophotometer (UV-vis) to study morphology, crystallographic structure, and optical property, respectively. The results showed that particle size, crystallinity, and transmittance of seed layers were changed with increasing concentrations of spin-coated precursor. Furthermore, the nanostructures were found that higher precursor concentration of seed layers affected the formation of ZnO nanorods to be nanosheets.

scholarly journals Facile synthesis of oriented zinc oxide seed layer for the hydrothermal growth of zinc oxide nanorods

2018 ◽  
Vol 53 (4) ◽  
pp. 233-244 ◽  
Author(s):  
SFU Farhad ◽  
NI Tanvir ◽  
MS Bashar ◽  
MS Hossain ◽  
M Sultana ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Seed Layer ◽  
Room Temperature ◽  
Zinc Acetate Dihydrate ◽  
Zno Nanorods ◽  
Zinc Oxide Nanorods ◽  
Yellow Emission ◽  
Zno Films ◽  
Near Band Edge ◽  
Seed Layers

Oriented zine oxide (ZnO) seed layers were deposited by simple drop casting of zinc acetate dihydrate (ZAD) solution on glass substrates at room temperature followed by a post-heat treatment at 250 oC. X-ray diffraction (XRD) analyses revealed that ZAD solutions with concentration 0.0025 – 0.0100 M produced amorphous type thin films, whereas 0.0200 M ZAD solutions produced ZnO seed layers with a preferential c-axis texturing.The Scanning Electron Microscopy (SEM) analyses evident that the morphology of ZnO seed layer surface is compact and coherently carpets the underlying glass substrate. ZnO nanorods were then grown by hydrothermal method atop the ZnO seeded and non-seeded substrates. The presence of ZnO seeding layers was found to be beneficial for growing ZnO NRs films vertically. The optical bandgap of ZnO seed and ZnO NR were estimated to be in the range of 3.40 – 3.95 eV and 3.20 – 3.25 eV respectively by using UV-VIS-NIR diffuse reflection spectroscopy. The room temperature photoluminescence analyses revealed that nanostructured ZnO films exhibit a sharp near-band-edge luminescence peak at ~380 nm consistent with the estimated optical band gap and the ZnO nanorod arrays are notably free from defect-related green-yellow emission peaks.Bangladesh J. Sci. Ind. Res.53(4), 233-244, 2018

scholarly journals Biosynthesis, characterization, and antibacterial activity of ZnO nanoaggregates using aqueous extract from Anacardium occidentale leaf: comparative study of different precursors

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Eric Kwabena Droepenu ◽  
Ebenezer Aquisman Asare ◽  
Boon Siong Wee ◽  
Rafeah Binti Wahi ◽  
Frederick Ayertey ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Antibacterial Activity ◽  
Comparative Study ◽  
Aqueous Extract ◽  
Zinc Chloride ◽  
Zinc Acetate ◽  
Zinc Acetate Dihydrate ◽  
Inhibition Zone ◽  
Anacardium Occidentale ◽  
Acetate Dihydrate

Abstract Background Various parts of Anacardium occidentale plant possess curative qualities like antidiabetic, anti-inflammatory, antibacterial, antifungal, and antioxidant. Aqueous extract of this plant leaf was used in biosynthesizing zinc oxide (ZnO) nanoaggregates using two precursors of zinc salt (zinc acetate dihydrate [Zn(CH3COO)2∙2H2O] and zinc chloride [ZnCl2]). The synthesized ZnO samples were used in a comparative study to investigate the antibacterial activity against selected Gram-positive and Gram-negative microbes [Staphylococcus aureus, Exiguobacterium aquaticum (Gram +ve) and Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii (Gram −ve)]. The synthesized ZnO nanoaggregates from the two precursors were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive x-ray spectroscopy (EDX) techniques. Results Micrographs of SEM and TEM confirmed nanoparticles agglomerated into aggregates. While spherical nanoaggregates were identified in samples prepared from Zn(CH3COO)2∙2H2O, flake-like structures were identified in samples synthesized from ZnCl2. Particle size determined by TEM was 107.03 ± 1.54 nm and 206.58 ± 1.86 nm for zinc acetate dihydrate and zinc chloride precursors respectively. ZnO nanoaggregate synthesized using zinc acetate as precursor gave higher antibacterial activity than its counterpart, zinc chloride with K. pneumonia recording the highest inhibition zone of 2.08 ± 0.03 mm (67.53%) whereas S. aureus recorded the least inhibition zone of 1.06 ± 0.14 mm (34.75%) for ZnO nanoaggregate from zinc chloride precursor. Also, antibacterial activity increases with increasing concentration of the extract in general. However, A. baumannii, E. aquaticum, and K. pneumoniae did not follow the continuity trend with regards to the 250 ppm and 500 ppm concentrations. Conclusion Biosynthesis of ZnO nanoaggregates using aqueous extract of A. occidentale leaf from zinc acetate dihydrate and zinc chloride as precursors was successful with the formation of nanospheres and nanoflakes. The study suggested that A. occidentale sp. could be an alternative source for the production of ZnO nanoparticles and are efficient antibacterial compounds against both Gram +ve and Gram −ve microbes with its promising effect against infectious bacteria.

Synthesis of 1,2-bis(3,4-dicyanophenoxymethyl)benzene and binuclear zinc phthalocyanines of clamshell and ball types

2003 ◽  
Vol 07 (03) ◽  
pp. 162-166 ◽  
Author(s):  
Alexander Yu. Tolbin ◽  
Alexey V. Ivanov ◽  
Larisa G. Tomilova ◽  
Nikolai S. Zefirov
Keyword(s):  
Microwave Irradiation ◽  
Zinc Acetate ◽  
Solid Phase ◽  
Large Excess ◽  
Type Reaction ◽  
Zinc Phthalocyanines

A novel 1,2-bis(3,4-dicyanophenoxymethyl)benzene was synthesized from 1,2-bis-(hydroxymethyl)benzene and 4-nitrophthalodinitrile. Its condensation with 4-tert-butylphthalodinitrile results in a binuclear phthalocyanine of clamshell type. Reaction of bisphthalodinitrile with a large excess of zinc acetate gives rise to a binuclear phthalocyanine of ball type (33% yield). The successful syntheses of these binuclear phthalocyanines were carried out by microwave irradiation and solid phase methods.

Early Stages of Oriented Attachment: Formation of Twin ZnO Nanorods under Microwave Irradiation

2012 ◽  
Vol 18 (42) ◽  
pp. 13265-13268 ◽  
Author(s):  
Monica Distaso ◽  
Mirza Mačković ◽  
Erdmann Spiecker ◽  
Wolfgang Peukert
Keyword(s):  
Microwave Irradiation ◽  
Zno Nanorods ◽  
Oriented Attachment ◽  
Early Stages

Influence of Growth and Annealing Temperatures on the Properties of ZnO Nanorods Synthesized by Dip Coating Method

2013 ◽  
Vol 678 ◽  
pp. 193-197
Author(s):  
Periyasamy Gowthaman ◽  
Manickam Saroja ◽  
Muthusamy Venkatachalam ◽  
Jagadeesh Deenathayalan ◽  
N. Muthukumarasamy ◽  
...  
Keyword(s):  
Optical Properties ◽  
Zinc Acetate Dihydrate ◽  
Zno Nanorods ◽  
Dip Coating ◽  
Zinc Nitrate ◽  
Annealing Temperatures ◽  
Air Atmosphere ◽  
Coating Method ◽  
Different Temperatures ◽  
Dip Coating Method

A novel and simple approach is reported to fabricate ZnO nanorods. Zinc acetate dihydrate, ethanol and de-ionized water were used to prepare seed layer. Zinc nitrate and hexamethylenetetramine solution were used for growth of ZnO nanorods. The ZnO nanorods were grown at two different temperatures of 90°C and 120°C and annealed at three different temperatures of 300°C, 400°C and 500°C in air atmosphere. Nanorod growth temperature and annealing temperature are varied and the corresponding changes in structural, morphological and optical properties were reported. The structure, orientation, surface morphology and optical properties of the ZnO nanorods were investigated by XRD, SEM & UV studies. The influence of growth and annealing temperatures on structural and optical properties were reported.

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