Synthesis of stable dispersion of ZnO quantum dots in aqueous medium showing visible emission from bluish green to yellow

Patra, Manoj Kumar; Manoth, M.; Singh, Vivek Kumar; Gowd, Genekehal Siddaramana; Choudhry, V.S.a; Vadera, Sampat Raj; Kumar, Nishant

doi:10.1016/j.jlumin.2008.10.014

Cited by 124 publications

(102 citation statements)

References 38 publications

(38 reference statements)

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“…Due to its wide band gap of 3.37 eV and large exciton binding energy of 60 meV (Wang et al 2009a), it exhibits stable UV emission (Duan et al 2006). Researchers reported that visible emission from the ZnO nanostructures originates because of the existence of various defects (Zn interstitial, Zn vacancy, and oxygen vacancy) in the ZnO nanocrystal (Nian et al 2010;Wang et al 2009b;Patra et al 2009). These emissions make ZnO, a very interesting material for various optoelectronic applications.…”

Section: Introductionmentioning

confidence: 99%

Chemical growth of hexagonal zinc oxide nanorods and their optical properties

Samanta¹,

Bandyopadhyay²

2011

Appl Nanosci

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A simple wet chemical method has been successfully deployed to fabricate hexagonal zinc oxide nanorods. The structural characteristics were investigated through X-ray diffraction. The crystal unit cell of the nanorods was found to be hexagonal. The morphology of the nanostructures was studied using field emission scanning electron microscopy and transmission electron microscopy. The nanorods are hexagonal in shape. The Zn-O bond formation was confirmed through Fourier transformed infrared spectroscopic analysis. Raman shift measurements revealed various vibrational modes present in the ZnO crystal. The photoluminescence spectrum shows shallow deep level visible emission due to various defect states. Thus, our investigation will be very helpful in the development of ZnO based light emitting/optoelectronic device applications.

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Section: Introductionmentioning

confidence: 99%

Chemical growth of hexagonal zinc oxide nanorods and their optical properties

Samanta¹,

Bandyopadhyay²

2011

Appl Nanosci

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“…Earlier studies suggested that defect emission in n-type doped QDs is due to the transition between the valence band edge under confinement and the defect states below the conduction band. 19,36 According to the above analysis, the DX energy shift due to the QSE (∆E QSE ) near the tips of the ZnO NNs for 85…”

Section: Resultsmentioning

confidence: 93%

“…One of the notable features in the lineshapes of TRPL was that the decay time rapidly decreased in the large θ range. The reduced decay time could be intuitively associated with the increase of the wavefunction overlap near the tip as the smaller scale confines the carrier motion, 39 occasionally reaching the quantum scale, as observed in QDs 36 and NRs. 37 On the other hand, the nonradiative decay time of bound excitons decreases via capture processes, which are plentiful in strain-induced TDs.…”

Section: Resultsmentioning

confidence: 97%

Distinctive mapping of strain and quantum size effects using depth-resolved photoluminescence in ZnO nanoneedles

Hwang

Baek

et al. 2016

AIP Advances

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In order to locate the spatially resolved influence of the strain, carrier localization, and quantum size effect (QSE) in tapered ZnO nanoneedles (NNs), the photoluminescence (PL) was measured as a function of the incident laser angle θ from 0• (normal to a surface) to 85• . With increasing θ, the excitation point is spatially restricted along the axis of the NNs and varies from the ZnO buffer/sapphire interface to the tips of the NNs. In this way, we identified a strain-induced blue-shift of 25.3 meV at the ZnO buffer/sapphire interface, which corresponds to a tensile strain of 0.319%. The influence of strain and the concomitant indications of carrier localization decreased as the excitation point moved to a higher location along the NNs with increasing θ whereas the QSE revealed an abrupt blue-shift near the tips of the NNs. Furthermore, timeresolved PL measurement as a function of the excitation angle was used to distinguish the strain effect from the QSE. We observed two spatially competing tendencies: (1) the decay times are influenced by the increase in the interfacial strain and (2) the decay times are influenced by the decrease in the diameter-dependent QSE near the tips of the tapered ZnO NNs. C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

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“…The ZnTe QDs synthesized at solution pH 6 exhibit most pronounced photoluminescence property. There are not obvious emission peak at other solution pH, besides, many emission peaks at about 500 nm appear at solution pH 9 and pH 11, which may be from ZnO [31][32][33]. On the contrary, the influence of ZnO or Zn(OH) 2 will disappear when the value of solution pH become six, growth of Zn(OH) 2 will be restrained when the solution is faintly acid.…”

Section: Resultsmentioning

confidence: 95%

Aqueous synthesis of high-fluorescence ZnTe quantum dots

Cheng

et al. 2015

J Mater Sci: Mater Electron

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High fluorescence ZnTe quantum dots (QDs) were prepared by one-step aqueous method in faintly acid solution. The detailed microstructure and morphology of the prepared ZnTe QDs has been characterized by X-ray powder diffraction and high resolution transmission electron microscopy, respectively. The average size of as-prepared ZnTe QDs is about 5 nm, which is hexagonal wurtzite structure. The PL spectra consists of a strong peak around 550 nm originating from surface state emission and a weak peak around 470 nm via band edge emission. Meanwhile, ZnTe/ZnSe QDs were prepared by passivating ZnSe shell on surface of ZnTe core, which effectively prevent the Tellurium ion oxidation to reduce the zinc carrier trap and the emission peak at about 470 nm has been strengthened. ZnTe/ZnSe QDs show a higher quantum yield (21.90 %) than ZnTe QDs (10.19 %). Moreover, ZnTe/ZnSe QDs exhibit excellent stability against time.

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Synthesis of stable dispersion of ZnO quantum dots in aqueous medium showing visible emission from bluish green to yellow

Cited by 124 publications

References 38 publications

Chemical growth of hexagonal zinc oxide nanorods and their optical properties

Chemical growth of hexagonal zinc oxide nanorods and their optical properties

Distinctive mapping of strain and quantum size effects using depth-resolved photoluminescence in ZnO nanoneedles

Aqueous synthesis of high-fluorescence ZnTe quantum dots

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