ChemInform Abstract: Luminescence and Photophysics of CdS Semiconductor Clusters: The Nature of the Emitting Electronic State.

Chestnoy, N.; Harris, T. D.; Hull, Robert; Brus, L. E.

doi:10.1002/chin.198642002

Cited by 33 publications

(55 citation statements)

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“…Such transition is often called excitonic [5], because an electron-hole pair generated by light absorption is similar to the Wannier-Mott exciton in a bulk crystal. In this paper, attention is paid to the particles with average sizes d= 2.5…2.8 nm, for which the excitonic Bohr radius (a B =5.4 nm) [6] exceeds a particle size.…”

Section: Absorption Spectroscopymentioning

confidence: 99%

Influence of the Particle Size on the Optical Properties of CdSe Nanoparticles

Gupta¹,

Ramrakhiani²

2009

TONANOJ

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Monodispersed CdSe nanoparticles with sufficient luminescence intensity have been prepared by chemical method in the presence of mercaptoacetic acid as a capping agent. Cadmium acetate (Cd(Ac) 2 .2H 2 O) and sodium selenosulfate (Na 2 SeSO 3 ) are used as a cadmium and selenium sources respectively. The resulting nanocrystallites have been characterized by X-Ray Diffraction, UV-Vis absorption spectra and photoluminescence (PL) spectroscopy. The particle size was estimated from broadening of XRD peak using Scherrer's formula and also from effective band gap by absorption peak using effective mass approximation model. The size obtained from XRD and absorption peaks are in agreement with each other. It is observed that the samples consist of separated, well-defined spherical particles and show a small size distribution as well as a characteristic blue shift due to quantum confinement in their optical absorption as well as PL spectra. It is found that the size of CdSe nanoparticles decreases, as the concentration of capping agent is increased. The intensity of PL peak increases and the peak shift towards blue region as the particle size is reduced. The sharp PL spectra also indicate that the nanoparticles are monodispersed.

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Section: Absorption Spectroscopymentioning

confidence: 99%

Influence of the Particle Size on the Optical Properties of CdSe Nanoparticles

Gupta¹,

Ramrakhiani²

2009

TONANOJ

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“…Other problems which have been treated are the role of surfaces and interfaces, but it is not intended to go into any of these details at this stage [44,45].…”

Section: Theoretical Estimationsmentioning

confidence: 99%

“…E x , D + , and D -will depend upon diameter D. In the purely radiative tunneling decay, close pairs with small R emit faster and at higher energy than distant pairs, for fixed D [44]. Donor and acceptor states can originate not from impurities, but from native defects, namely surface atoms, or vacancies in various configurations [18].…”

Section: Donor-acceptor Pairsmentioning

confidence: 99%

“…This technique gives information about electronic transitions in QDs, nonradiative relaxation, quantity of electron-hole pairs per QD, etc. In particular, study of excitation dependence of time--resolved (dynamical) and steady-state photoluminescence gives information about biexcitonic, and multyexcitonic processes in QDs [18,19,44,51]. Measurements of charging/recharging processes in a electrochemical cell which contains electrolyte and QDs provide information for suggesting if the trap is a hole trap or an electron trap, this is a peak of current which appears in a cyclic voltammetry spectrum at positive or negative bias.…”

Section: Photoluminescence Techniquesmentioning

confidence: 99%

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Defects in quantum dots of IIB–VI semiconductors

Babentsov

Сизов

2008

Opto-Electronics Review

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This review discusses the properties of structural defects in quantum dots of IIB–VI semiconductors. A great part of this knowledge has been developed in the last years and combined with the improvement in passivation technologies has contributed significantly to the nanotechnology.In this review we introduced the main characterization methods which are used for the study of defects in the nanoform of semiconductors, presented a short description of how native defects can influence the emission spectra, underlined the restrictions which the Auger and deep-level defect recombination imposes on the excitonic emission. We also highlighted the importance of the defect passivation associated with efficiency and photostability of devices.

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“…It has been demonstrated that semiconductor nanocrystals prepared by thermolysis of the precursors in highly coordinating solvents (trioctylphosphine oxide and/or trioctylphosphine) undergo a size distribution focusing process upon slowing the growth and making the growth diffusion controlled [8]. Various methods have been used to control the semiconductor nanocrystal growth in water such as using specific capping agents such as thioglycerol [5,6], alcohols [9] and surfactants [10]. Furthermore, the compartmentalization afforded by the aqueous domains of a water-in-oil microemulsion has shown to be effective [11,12].…”

Section: Introductionmentioning

confidence: 99%

Growth Mechanisms of CdS Nanocrystals in Aqueous Media

Latterini

Iagatti

2012

Crystals

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CdS nanocrystals were prepared in water-in-oil microemulsions. The nanocrystal properties, absorption and luminescence spectra and size distributions, were monitored at different times after mixing the microemulsions of the two precursors to obtain information on their growth mechanism. In particular, CdS nanocrystals were prepared using water-in-heptane or water-in-nonane microemulsions. The results obtained from the investigation of nanocrystals prepared using heptane as the organic phase, confirmed that nanocrystal nucleation is fast while their growth is determined by droplet exchange content rate. Size distribution histograms obtained from the sample at early time points after mixing presented a bimodal population having average sizes of 3.0 ±0.1 and 5.8 ±0.1 nm, thus indicating that surface process controls the nanocrystal growth. With longer reaction times the occurrence of water droplet coalescence is likely responsible for the formation of nanocrystal agglomerates. Using a water-in-nonane microemulsion, the droplet exchange rate can be modified, thus leading to smaller CdS nanocrystals. However, the development of structural defects cannot be excluded, as evidenced by the luminescence spectra of the suspension. In general, aging of the nanocrystal in the pristine microemulsion resulted in the development of cubic semiconductor nanostructures.

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ChemInform Abstract: Luminescence and Photophysics of CdS Semiconductor Clusters: The Nature of the Emitting Electronic State.

Abstract: The luminescence of CdS Clusters prepared by arrested precipitation has been studied as function of time, temp., wavelength, and physical size.

Cited by 33 publications

References 1 publication

Influence of the Particle Size on the Optical Properties of CdSe Nanoparticles

Influence of the Particle Size on the Optical Properties of CdSe Nanoparticles

Defects in quantum dots of IIB–VI semiconductors

Growth Mechanisms of CdS Nanocrystals in Aqueous Media

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