Semiconductor nanoparticles optoelectronic property

The quantum effect of reduction of particle size in reducing the band gap of semiconductors and so giving rise to novel optoelectronic properties has stimulated interest in quantum dot inclusion compounds of nanoparticles of semiconductors within zeolite pores.In a pioneering study, Herron and coworkers succeeded in introducing cadmium sulfide clusters within the pores of zeolite Y via the reaction of a cadmium-exchanged zeolite Y with hydrogen sulfide gas (Scheme 6.8). °... 

Abstract Semiconductor nanoparticles have attracted much attention due to their unique size and properties. Semiconductor-polymer hybrid materials are of great importance in the field of nanoscience as they combine the advantageous properties of polymers with the unique size-tunable optical, electronic, catalytic and other properties of semiconductor nanoparticles. Due to combination of the unique properties of organic and inorganic components in one material, these semiconductor-polymer hybrids find application in environmental, optoelectronic, biomedical and various other fields. A number of methods are available for the synthesis of semiconductor-polymer hybrid materials. Two methods, i.e. melt blending and in-situ polymerization, are widely used for the synthesis of semiconductor-polymer nanocomposites. The first part of this review article deals with the synthesis, properties and applications of semiconductor nanoparticles. The second part deals with the synthesis of semiconductor-polymer nanocomposites by melt blending and in-situ polymerization. The properties and some applications of semiconductor-polymer nanocomposites are also discussed. 

Moreover, the surface state also plays a very important role in the nanoparticles, due to their large surface area-to-volume ratio, with a decrease in particle size (surface effects). In the case of semiconductor nanoparticles, radiative or nonradiative recombination of an exciton at the surface states becomes dominant in its optical properties with a decrease in particle size. Therefore, the decay of an exciton at the surface states will influence the qualities of the material for an optoelectronic device. Ultrasmall semiconductor crystals are known in the literature as nanocrystals, particles with quantum size effect or nanoparticles [141]. 

Semiconductor-polymer hybrids are an important class of materials because of their combined properties of polymers and semiconductor nanoparticles. A number of methods are available for the synthesis of semiconductor-polymer hybrids from semiconductor nanoparticles, such as melt blending and in-situ polymerization. Semiconductor-polymer hybrids find applications in environmental, optoelectronic, biomedical and various other fields. 

Other materials derived from clay-organic systems include small semiconductor nanoparticles (CdS, for instance), which are extremely interesting in terms of new nanoelectronic and optoelectronic devices. The functionalization of sepio-lite using 3-MPTMS (see Sec. VI.A) allows complexation of Cd ions by thiol-cation interactions (200). These materials are potentially very attractive for their quantum dot properties, because it can be expected that treatment with H2S gas or Na2S solutions could produce semiconducting CdS particles of nanosized dimensions. In addition, such systems would be of interest in terms of photocata-lytic activity, such as for the generation of H2 from isopropanol, as was observed for MCM mesoporous silica that was functionalized in a similar way (230). 

Other interesting nanoparticles that have been explored for various applications are those of cadmium sulfide (CdS). These are semiconductor nanoparticles possessing remarkable photoluminescence properties that can be used in optoelectronics, bio-labeling, lasing, photovoltaics, and so on. For these reasons, they must be... 

In this chapter, we would like to present few of our important findings on the size-, shape- and composition dependent structural, electronic and optical properties of some representative II-VI and III-V semiconductor nanoparticles. These semiconductors have become a popular research pursuit owing to the richness of their physical and chemical properties and wide range of possible applications. The observed nanostructure morphologies are not only very rich but their size also plays a very important role for developing next generation optoelectronic devices. 

The optoelectronic properties of semiconductor nanoparticles are dominated by excitonic effects, in particular by the recombination of the electron-hole pairs forming the excitons. To a first approximation the excitonic... 

Much of the research interest in nanomaterials is attributable to the remarkably different properties displayed by these fascinating materials. For example, the prediction of size-dependent bandgaps for nanocrystalline semiconductors has excited speculation about their exploitation in novel optoelectronic and photoelectrochemical applications. Due to the relative ease with which they may be synthesized, most work to date has focused on metal nanoparticles and nanocrystalline II-VI (12-16) semiconductors. Despite the tremendous potential of unique properties and applications, however, nanocrystalline III-V (13-15) semiconductors remain largely unexplored. To this end, the work reported here details two different routes for the synthesis of nanocrystalline Ill-V materials, and discusses the characterization of these materials. In particular, it will be shown that stable, conductive, nanocrystalline materials with a reasonably narrow size distribution can be prepared which have a markedly different bandgap than commercial wafers of the bulk material. 

Cadmium sulphide (CdS) is an II-VI semiconductor material with a direct band gap of 2.42 eV at room temperature with many outstanding physical and chemical properties, which has promising applications in photochemical catalysis, gas sensors, detectors for laser and infrared, solar cells, nonlinear optical materials, luminescence devices and optoelectronic devices [36-39]. CdS also exhibited excellent visible light detecting properties [40]. In the last decades, many techniques have been reported on synthesis of CdS nanoparticles [41-43]. 

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