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Bulanyǐ, M. F.; Коваленко, А. В.; Polezhaev, B. A.

doi:10.1023/a:1022661121438

Cited by 17 publications

(11 citation statements)

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“…Hence, the impediment experienced by the 5 D 0 -7 F 2 transition by a time constant of 1038 s is attributed to electric dipole allowed and spin and parity forbidden transitions. 22,23 In summary, we have demonstrated a method for dispersing YVO 4 : Eu QDs as uniform 2D layers, which upon heat treatment coalesce to form nanoclusters with size of ϳ25 nm. The PL brightness of the layers increased many times and showed reversible photobleaching feature when exposed to high energy UV ͑254 nm͒ for more than 30 min.…”

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confidence: 96%

Controlled surface distribution and luminescence of YVO4:Eu3+ nanophosphor layers

Khan

Haranath

Yadav

et al. 2008

Applied Physics Letters

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A method of dispersing YVO 4 : Eu quantum dots ͑QDs͒ as uniform two-dimensional ͑2D͒ layers with a high degree of homogeneity is presented. Annealing at 773 K resulted in coalescence of QDs to form nanoclusters with size of ϳ25 nm with an improved photoluminescence and ϳ80% transmittance at 800 nm. An efficient 5 D 0 -7 F 2 transition and lifetimes of ϳ1038 s for the characteristic Eu 3+ emission were observed. The absorption and emission peaks showed a slight blueshift, due to quantum-size effect, as compared to that for the bulk counterpart. Our method of 2D layer deposition is useful to enhance spectral response of the solar cells. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2973163͔ Quantum dots ͑QDs͒ have attracted much attention due to their potential applications for many high performance devices, 1 viz., the Si-solar cell 2 and QD based light emitting diodes.3 Chemically synthesized 4,5 QDs with precise size ͑Ͻ5 nm͒ control and a suitable organic/inorganic cap are currently available for many practical applications. 6 The QDs of phosphor materials could be even more interesting as they do not scatter light and show enhanced emission efficiencies 7 and radiative lifetime shortening. 8 The spatially distributed phosphor QDs can act as a thin layer having good optical transparency and high emission characteristics. Such a layer can be useful for increasing the power conversion efficiency of a solar cell. The objective of the present study is to fabricate highly transparent and luminescent two-dimensional ͑2D͒ layer using inorganic capped YVO 4 QDs that possess the advantages of quantum-size effect. Annealing treatments performed to the layers not only initiated the nanocluster formation but also provided a proper thermal encapsulation, adherence, and increased PL emission related efficiencies.In utilizing nanoparticles for device technology one of the fundamental issues is how to distribute nanoparticles uniformly over a substrate with a precise control of particle density. In most of the studies, the self-assembly scheme has been employed using the chemical interaction between the nanoparticles and the substrate.9-11 This method is effective in achieving a dense layer of nanoparticles. However, the control of the particle density is difficult at submonolayer regime. Moreover, special chemical treatments of the substrate surface are needed and the results are sensitive to local chemical environment with enhanced defect susceptibility.In this letter, we demonstrate the fabrication of uniformly distributed sodium hexametaphosphate ͑SHMP͒ capped YVO 4 : Eu nanophosphor layer with controlled particle density using the conventional spin-coating method followed by annealing treatment.It is well known that the OH − groups show significant luminescence quenching behavior for most of the inorganic QDs.12 Commonly, researchers synthesize YVO 4 : Eu nanophosphor by wet-chemical methods and protect the surface atoms by phosphate capping followed by redispersion in deionized water. This results in fully hydrat...

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confidence: 96%

Controlled surface distribution and luminescence of YVO4:Eu3+ nanophosphor layers

Khan

Haranath

Yadav

et al. 2008

Applied Physics Letters

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“…[12][13][14] For ZnS materials, the lattice energy is much lower (À3319 kJ mol À1 ), 11 and internal lattice defects could be more easily formed, which will lead to a poor crystal integrity of the material. [15][16][17] On the other hand, for direct band materials, since the phonon is not involved in the process of electron transition, the photogenerated carriers can be more easily captured by all forms of defects. Thus it will reduce the probability that the photocarriers diffuse to the surface of the material, and reduce the generation of the free radicals as well.…”

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confidence: 99%

Study on the influence of lattice integrity and phase composition to the photocatalytic efficiency of ZnS material

et al. 2011

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“…For C Mn ≥ 1⋅10 -3 , the electroluminescence spectra generally contain only "manganese" emission. Analysis of the voltage-brightness characteristics shows that the shape of the voltage-brightness characteristics depends not only on the frequency of the exciting voltage (shown earlier in [11]) but also on the sample temperature. Thus at T = 300 K, when electroluminescence is excited by an a.c. voltage of frequency f = 50 Hz, the change in the brightness of luminescence is described by the law…”

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confidence: 88%

Temperature dependence of photoluminescence and electroluminescence of ZnS:Mn crystals

et al. 2006

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535.37:548By means of comprehensive analysis of the temperature dependences of the photoluminescence for ZnS:Mn crystals, we have observed persistent changes in the intensity, shape, and position of the maximum in the emission spectrum associated with changes in the immediate environment of the manganese luminescence centers. We have also observed inflection points on the voltage vs. brightness characteristics of the samples, the position of which depends on the frequency of the exciting voltage and the temperature. The observed dependences are explained using concepts describing the mechanisms of pre-breakdown luminescence.Introduction. The complex structure of the "manganese" emission band in ZnS:Mn crystals, associated with different local environments of the Mn 2+ ions in the crystal lattice [1-3], means complex temperature dependences of the optical characteristics of ZnS. In this work, we studied the effect of temperature on the intensity of emission for photoluminescence (PL) and electroluminescence (EL) of ZnS:Mn single crystals.Samples and experimental procedure. Samples of the crystals were grown from the melt under argon pressure. The salt α-MnS was used as the activator. The original crystals with microtwinned structure and cubic 3C symmetry consisted of microblocks misoriented relative to each other by 2-3 o . For excitation of photoluminescence, we used LGI-505 and LGN-517 lasers with wavelengths of λ ex = 337 nm and 441 nm, which in the first case corresponds to intrinsic absorption of ZnS and in the second case corresponds to one of the absorption bands of the Mn 2+ ion in the ZnS crystals, associated with the transition 6 A 1 ( 6 S) →

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Cited by 17 publications

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Controlled surface distribution and luminescence of YVO4:Eu3+ nanophosphor layers

Controlled surface distribution and luminescence of YVO4:Eu3+ nanophosphor layers

Study on the influence of lattice integrity and phase composition to the photocatalytic efficiency of ZnS material

Temperature dependence of photoluminescence and electroluminescence of ZnS:Mn crystals

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