Photoluminescence and photoinduced oxygen adsorption of colloidal zinc sulfide dispersions

Becker, William G.; Bard, Allen J.

doi:10.1021/j150642a026

Cited by 447 publications

(289 citation statements)

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“…Although we also notice in Fig. 1 that the particles may be grains formed from several crystallites touching side to side, the grain sizes ͑or the degree of the particle aggregation͒ are believed, from earlier reports, 7,8 to have increased during the process of TEM sample preparation. Accordingly, the sample treated for the TEM observation was not used for the optical experiments.…”

Section: Resultsmentioning

confidence: 51%

Luminescence properties of ZnS phosphor nanocrystals prepared by the laser-induced gas-evaporation method

Tanaka¹,

Sawai

Sengoku

et al. 2000

Journal of Applied Physics

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Nanocrystalline particles of ZnS:͑Ag, Al͒ semiconductor phosphor, whose sizes are mostly 3-5 nm in diameter, are prepared by the gas-evaporation method with cw CO 2 laser heating. The Raman scattering spectrum as well as the transmission electron microscope observation demonstrates that the crystallization of the nanoparticles was caused successfully through the gas-phase condensation. Under irradiation of ultraviolet light, the nanoparticles exhibit blue luminescence, as in the case of the starting material of ZnS:͑Ag, Al͒ bulk powder. The peak of the luminescence spectrum of the nanoparticles shifts to lower energy with increasing delay time and also with decreasing excitation intensity, showing that the luminescence originates from the donor-acceptor pair recombination. However, it is concluded that the luminescence of the nanoparticles is not ascribed to the blue Ag luminescence mechanism responsible for the luminescence of the bulk powder, by taking into account the spatial confinement of an electron trapped at the donor and a hole at the acceptor. It is argued that the luminescence mechanism of the nanoparticles is the so called self-activated luminescence, which involves zinc vacancies.

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Section: Resultsmentioning

confidence: 51%

Luminescence properties of ZnS phosphor nanocrystals prepared by the laser-induced gas-evaporation method

Tanaka¹,

Sawai

Sengoku

et al. 2000

Journal of Applied Physics

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“…It is interesting to note that a similar trend was observed for large (∼1 µm) ZnS:Mn 2+ colloidal systems. 18 However, for these large particles the effect on the ZnS-related luminescence was not as pronounced, which is probably due to the much smaller surface-to-volume ratio of these colloids. The change in emission spectrum of the nanocrystals did not change the overall quantum efficiency significantly.…”

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confidence: 95%

Synthesis and Photoluminescence of Nanocrystalline ZnS:Mn²⁺

et al. 2001

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The influence of the synthesis conditions on the properties of nanocrystalline ZnS:Mn 2+ is discussed. Different Mn 2+ precursors and different ratios of the precursor concentrations [S 2-]/[Zn 2+ ] were used. The type of Mn 2+ precursor does not have an effect on the luminescence properties in the synthesis method described. On going from an excess of [Zn 2+ ] to an excess of [S 2-] during the synthesis, the particle diameter increases from 3.7 to 5.1 nm, which is reflected by a change in the luminescence properties. Photoluminescence measurements also showed the absence of the ZnS defect luminescence around 450 nm when an excess [S 2-] is used during the synthesis. This effect is explained by the filling of sulfur vacancies. The ZnS luminescence is quenched with an activation energy of 62 meV, which is assigned to the detrapping of a bound hole from such a vacancy.Over the past few years, considerable interest in the novel optical and electrical properties of doped semiconductor nanocrystals (NC) has emerged. 1-5 These structures are interesting from a physical and chemical point of view mainly because several of their properties are very different from those of bulk materials. 3 Especially, the significant sizedependent shift in the band gap has attracted much attention. This so-called quantum-size effect allows one to tune the emission and excitation wavelengths of a nanocrystal by tuning the crystal radius r. A quite good first-order approximation to calculate the energy of the band gap is given by the Brus equation. 1 In the case of zinc blende ZnS, the bulk values of all the materials parameters are known. 6 For nanocrystalline ZnS this results in a relation between the particle radius r, in nanometers, and the band gap E, in electronvolts, as follows:Manganese-doped materials represent a class of phosphors that have already found their way into many applications. The 4 T 1 f 6 A 1 transition within the 3d 5 configuration of the divalent manganese ion (Mn 2+ ) has been studied extensively and its orange-yellow luminescence in ZnS is well documented. This luminescence was also observed in nanocrystalline ZnS:Mn 2+ 7,8 and applications have already been suggested. 9-11 Different types of Mn 2+ centers are present in nanocrystalline ZnS:Mn 2+ . 12,13 The orange luminescence originates from Mn 2+ ions on Zn 2+ sites, where the Mn 2+ is tetrahedrally coordinated by S 2-.Previous workers have always used equal concentrations of Zn 2+ and S 2-precursors in the synthesis of these ZnS: Mn 2+ nanocrystals. This letter will focus on the effect of the synthesis conditions on several properties of these nanocrystals. Two different Mn 2+ precursors were used and the influence of the ratio of [Zn 2+ ] to [S 2-] was investigated. The experimental comparison will include measurements of the diameter, reflectivity, temperature-dependent photoluminescence (PL) emission and excitation as well as luminescence lifetimes. From these results, new insights into the ZnS-related luminescence are obtained and a qualitative...

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“…[15][16][17] Several reports in the literature describe the conditions required for PL. [18][19][20][21] In this paper, we present a comparative study of an intense and broad PL at room temperature for ZnS nanocrystals synthesized by an efficient microwave-assisted solvothermal method, [22][23][24] for different times to clarify the roles capping agents play in the enhanced PL activity of ZnS. The origin of the intense PL bands was investigated by electronic structure calculations carried out within the framework of ab initio periodic quantum-mechanical techniques.…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical studies on the enhanced photoluminescence activity of zinc sulfide with a capping agent

Santana

Raubach

Ferrer

et al. 2011

Journal of Applied Physics

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The photoluminescence (PL) emission from zinc sulfide (ZnS) synthesized by the microwave-assisted solvothermal method in the presence/absence of a capping agent was examined to understand the key role of its PL activity. In addition, we also investigated the electronic structure using a first-principle calculation based on density functional theory (DFT) applied to periodic models at BÁLYP level. Two models were selected to simulate the effects of structural deformation on the electronic structure; the ordered o-ZnS model and the disordered d-ZnS model, dislocating the Zn atom, 0.1 Å , in the z-direction. The PLemission in the visible region showed different peak positions and intensities in capped and uncapped ZnS. The PL emission was linked to distinct distortions in lattices and the emission of two colors, green in the capped and blue in the uncapped, was also examined in the light of favorable structural and electronic conditions. The computational simulations indicate that the electronic behavior can be associated with the new electronic levels above the valence band.

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Photoluminescence and photoinduced oxygen adsorption of colloidal zinc sulfide dispersions

Cited by 447 publications

References 1 publication

Luminescence properties of ZnS phosphor nanocrystals prepared by the laser-induced gas-evaporation method

Luminescence properties of ZnS phosphor nanocrystals prepared by the laser-induced gas-evaporation method

Synthesis and Photoluminescence of Nanocrystalline ZnS:Mn²⁺

Experimental and theoretical studies on the enhanced photoluminescence activity of zinc sulfide with a capping agent

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Photoluminescence and photoinduced oxygen adsorption of colloidal zinc sulfide dispersions

Cited by 447 publications

References 1 publication

Luminescence properties of ZnS phosphor nanocrystals prepared by the laser-induced gas-evaporation method

Luminescence properties of ZnS phosphor nanocrystals prepared by the laser-induced gas-evaporation method

Synthesis and Photoluminescence of Nanocrystalline ZnS:Mn2+

Experimental and theoretical studies on the enhanced photoluminescence activity of zinc sulfide with a capping agent

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Synthesis and Photoluminescence of Nanocrystalline ZnS:Mn²⁺