Quantum Size Effects in the Photonics of Semiconductor Nanoparticles

Stroyuk, A. L.; Kryukov, A. I.; Kuchmii, S. Ya.; Pokhodenko, V. D.

doi:10.1007/s11237-005-0025-9

Cited by 50 publications

(36 citation statements)

References 310 publications

(397 reference statements)

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“…With the introduction of Ag and Au nanoparticles into the ternary TiO 2 /ZrO 2 /SiO 2 nanocomposites, for both systems the E gi value increases up to 3.6 eV, E gd -up to 4.2 eV. It is possible that the increase of the bandgap width observed in the ternary nanocomposites and in films with noble metal nanoparticles is related with the quantum-size limitations of excitons that are manifested when decreasing the TiO 2 crystallite sizes due to the presence of SiO 2 oxides and Ag and Au metal nanoparticles [2,12,15].…”

Section: Resultsmentioning

confidence: 99%

Electron structure of TiO 2 composite films with noble metal nanoparticles

Busko¹

2014

Semicond. Phys. Quantum Electron. Optoelectron.

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Abstract. Thin nanocrystalline films of ТіО 2 , TiO 2 /ZrO 2 , TiO 2 /ZrO 2 /SiO 2 , TiO 2 /ZrO 2 /SiO 2 /Ag and TiO 2 /ZrO 2 /SiO 2 /Au were prepared using the sol-gel synthesis method. In this paper, we determined the bandgap for direct and indirect band-to-band transitions. Optical conductivity of the films was determined using the spectral ellipsometry method. Depending on the nanocomposite composition, optical conductivity is of different character due to light absorption caused by the presence of the structure intrinsic defects: oxygen vacancies (F 2+ , F, and F + centers), Ti 3+ ions and interstitial Ti atoms. Rearrangement of the electron spectrum in these thin films due to the aforementioned defects can improve photocatalytic activity in the UV and visible spectral ranges.

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Section: Resultsmentioning

confidence: 99%

Electron structure of TiO 2 composite films with noble metal nanoparticles

Busko¹

2014

Semicond. Phys. Quantum Electron. Optoelectron.

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“…The long wavelength edge of the absorption band (l tr ) of aqueous colloidal solutions of cadmium sulfide, stabilized with NaPP with [CdS] = 1·10 -3 mol/L and [NaPP] = 3·10 -3 mol/L is at 470-473 nm, which corresponds to the width of the forbidden band E g = 2.63 ± 0.01 eV (Fig, 1), the value of which is increased by DE g = 0.23-0.24 eV as a result of quantum size effects [1,2] from the known value of E g = 2.4 eV for bulky crystalline cadmium sulfide [7]. The comparatively small increase in E g for SC NP relative to the compact SC shows that nanocrystals of CdS are found in a regime of weakly spatial limitation of the exciton, which is described well by model of the effective mass of the charge carrier [1, 2]:…”

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confidence: 99%

Photoinduced variations in the size of nanoparticles of CdS in colloidal solutions

et al. 2007

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The possibility of decreasing the size of colloidal nanoparticles of CdS in the oxidative photocorrosion reaction in the presence of methylviologen and of increasing their size during photocatalytic reduction of sulfur in ethanol in the presence of cadmium acetate. A dependence of the quantum yield of the latter reaction on the initial size of CdS nanoparticles was observed, which was interpreted as a result of quantum size effects.The unique luminescent, non-linear optical and photochemical properties of semi-conductor (SC) nanoparticles (NP), the character and intensity of which in many cases are functions of the size of the NP [1-5] has stimulated considerable interest in the methods of synthesis which permit purposeful and gradual variation in size of the SC NP [4,5]. Among the approaches to obtain "homologous" series of SC NP, the dimensions and optical properties of which, at constant chemical composition, change over a wide range, the most successful are methods based on formation of the SC NP in a structured medium (e.g. micellar), and also the use of Ostwald ripening of SC NP at high temperatures in high boiling solvents [4,5]. In addition to this the possibility of using such SC NP, for example, in photochemical reaction is very limited since such methods require carrying out difficult procedures to extract the NP from the micellar medium or an organic oil and then to stabilize them in solution. In the case of cadmium sulfide and a series of other photoactive SC which take part in photochemical conversions which may be used for "photopoisoning" of the SC NP which permits changes of the size and distribution of the NP with respect to size [6].In the present work it is shown that the size of CdS NP can be gradually changed photochemically -either a decrease in size during oxidative photocorrosion in aqueous solution in the presence of methylviologen or an increase in size in the photocatalytic process of formation of cadmium sulfide by reduction of elemental sulfur in the presence of NP of CdS and cadmium acetate in ethanol solutions. EXPERIMENTALIn this work the following chemicals were used: CdCl 2 , Cd(CH 3 COO) 2 , Na 2 S·9H 2 O, methylviologen chloride (MV 2+ ), sodium polyphosphate (NaPP) (chemically pure) (Aldrich), and sulfur (very pure). Ethanol was dehydrated by boiling with calcined calcium oxide and redistilled twice. Nanoparticles of CdS were obtained in aqueous solutions of sodium polyphosphate (3·10 -3 mol/L) by the interaction of cadmium chloride and sodium sulfide (1·10 -3 mol/L), and also in anhydrous 184 0040-5760/07/4303-0184

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“…The accumulation of data on the properties of semiconducting (SC) nanomaterials, which has occurred particularly rapidly in the last 7-10 years, has opened up ever more alluring prospects for their application as light-sensitive and light-emitting components in nanophotonics [1][2][3], nanophotocatalysis [2,[4][5][6][7], biosensorics [8][9][10][11], and other important fields. The possibility of practical utilization is an important factor that has stimulated the search for and study of the processes involved in the formation of nanomaterials.…”

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Photochemical formation of semiconducting nanostructures

et al. 2008

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Existing data on photochemical and photocatalytic approaches to the formation of semiconducting nanoparticles and also binary semiconducting nanostructures and nanocomposites of semiconductors with metals and polymers are reviewed. The nature of the effect of irradiation on the synthesis and properties of the obtained nanostructures and the possibility of photocatalytic control of the structural and spectral parameters of nanostructural semiconducting systems are examined.The accumulation of data on the properties of semiconducting (SC) nanomaterials, which has occurred particularly rapidly in the last 7-10 years, has opened up ever more alluring prospects for their application as light-sensitive and light-emitting components in nanophotonics [1-3], nanophotocatalysis [2,[4][5][6][7], biosensorics [8][9][10][11], and other important fields. The possibility of practical utilization is an important factor that has stimulated the search for and study of the processes involved in the formation of nanomaterials. On this account an enormous number of publications have now accumulated on the improvement of existing and development of new methods for the synthesis of semiconducting nanoparticles and nanostructures (e.g., see the reviews [6, 12-15]). A special position among them is occupied by methods based on photochemical transformations conducted either for the purpose of synthesis and directing it along a desired path or for improving the characteristics of nanostructures produced by other methods.Photochemical methods of synthesis have proved more effective than the production of nanomaterials by traditional synthetic approaches, and in a number of cases only they make it possible to achieve the assigned aim. For this reason the synthesis of semiconducting nanostructures and their modification under the conditions of photoirradiation are constantly attracting the attention of investigators, and the number of publications devoted to these questions is constantly increasing. We note, however, that they nevertheless remain disjointed.In view of the foregoing an attempt is made in the present article to organize existing data, to identify the most important directions for research and development, and thus to assess the current state of development of photochemical approaches to the formation of semiconducting nanostructures. Analysis of data on the photochemical formation and post-synthesis photochemical treatment of semiconducting nanostructures and multicomponent nanocomposites, including the nanoparticles of metals and polymers in addition to semiconductors, showed that in spite of the variety and diversity of the proposed approaches all the papers can be ascribed to only three courses: synthesis, synthesis control, and changing the characteristics of the semiconducting nanostructures. For this reason in this review photochemical approaches to the synthesis of nanoparticles of metal chalcogenides, binary semiconducting nanostructures, and nanocomposites consisting of semiconducting and conducting polymers are examin...

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Quantum Size Effects in the Photonics of Semiconductor Nanoparticles

Cited by 50 publications

References 310 publications

Electron structure of TiO 2 composite films with noble metal nanoparticles

Electron structure of TiO 2 composite films with noble metal nanoparticles

Photoinduced variations in the size of nanoparticles of CdS in colloidal solutions

Photochemical formation of semiconducting nanostructures

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