Nanoparticle semiconductor-polymer

Radiolytic Production of Semiconductor Nanoparticles in Polymer Matrices.523... 

RADIOLYTIC PRODUCTION OF SEMICONDUCTOR NANOPARTICLES IN POLYMER MATRICES... 

Investigating the fabrication and composition of semiconductor nanoparticles in polymer matrices has attracted the interest of many scientists. Inorganic/organic polymer nanocomposites, in particular, have attracted great interest due to their synergistic and hybrid properties derived from... 

A gas-solid reaction was further introduced to the electrospiiming technique to incorporate semiconductor nanostructures into polymer nanofibers with better dispersion. The production of well-dispersed PbS nanoparticles in polymer fiber matrices has been achieved by this method (Lu et al., 2005). First, metal salt and polymer were codissolved into one solvent to make a homogeneous solution. Then the above solution was electrospun to obtain polymer/metal salt composite nanofibers. The composite nanofibers were finally exposed to HaS gas at room temperature to synthesize PbS nanoparticles in situ in polymer nanofibers. 

Self-assembly of nanoparticles with polymers is providing access in order to stabilize metal and semiconductor nanocomposites for fabrication of new materials. Characteristics of the individual building blocks mainly include the following (Skaff et al., 2008) ... 

In summary, CPs offer numerous advantages over inorganic semiconductors for thermoelectric applications because of their unique properties. However, the poor electrical transport properties have impeded their practical application as TE materials in the past. Recent studies indicate that incorporating the inorganic nanoparticle into polymer matrix is an effective way to improve the electrical transport properties of CPs, including electrical conductivity and Seebeck coefficient, while keep the thermal conductivity at low level simultaneously. Consequently, the power factors of most CP-based nanocomposites are about 2 3 orders of magnitude higher than those of conventional pure CPs and the maximum ZT value is up to 0.1 at present. 

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. 

Melt processing of semiconductor nanoparticles in polymer melt may result in turbidity/translucency of the resulting composite materials due to strong tendency of nanoparticles to form aggregates [230]. The method of in-situ polymerization has been developed and widely used to overcome this problem. 

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. 

Production of metal and semiconductor nanoparticles in polymer systems. Dendrimers are used for the synthesis of metallic nanoparticles via dissolution of a metal precursor in a supercritical fluid followed by reduction. 

Moffit, M. et al. (1995) Size control of nanoparticles in semiconductor-polymer composites. 2. Control via sizes of spherical ionic microdomains in styrene-based diblock ionomers. Chemistry of Materials, 1,1185-1192. 

Hybrid solar cells where a conjugated polymer is blended with an inorganic nanoparticle have also been the subject of intense research in recent years. BHJ hybrid solar cells have been fabricated by blending inorganic materials such as ZnS, Ti02, and CdSe in the form of nanoparticles, nanorods, or nanowires with a semiconductor polymer into a thin It is... 

Nanoclusters/Polymer Composites. The principle for developing a new class of photoconductive materials, consisting of charge-transporting polymers such as PVK doped with semiconductor nanoclusters, sometimes called nanoparticles, Q-particles, or quantum dots, has been demonstrated (26,27). 

Particularly attractive for numerous bioanalytical applications are colloidal metal (e.g., gold) and semiconductor quantum dot nanoparticles. The conductivity and catalytic properties of such systems have been employed for developing electrochemical gas sensors, electrochemical sensors based on molecular- or polymer-functionalized nanoparticle sensing interfaces, and for the construction of different biosensors including enzyme-based electrodes, immunosensors, and DNA sensors. Advances in the application of molecular and biomolecular functionalized metal, semiconductor, and magnetic particles for electroanalytical and bio-electroanalytical applications have been reviewed by Katz et al. [142]. 

Research on semiconductor nanoparticle technology by chemists, materials scientists, and physicists has already led to the fabrication of a number of devices. Initially, Alivisatos and co-workers developed an electroluminescence device from a dispersion of CdSe nanoparticles capped with a conducting polymer349 and then improved on this by replacing the polymer with a layer of CdS, producing a device with efficiency and lifetime increased by factors of 8 and 10, respectively. 0 Chemical synthetic methods for the assembly of nanocrystal composites, consisting of II-VI quantum dot polymer composite materials,351 represent one important step towards the fabrication of new functional devices that incorporate quantum dots. 

A number of matrices have also been used for the preparation of semiconductor nanoparticles, whereby the particulate material is grown within and subsequently fills the cavities of the host material. These includes zeolites,361 glasses,362 and molecular sieves,363-365 and can be viewed as nanochambers which limit the size to which crystallites can grow. Other synthetic methods include micelles/microemulsions,366-369 sol-gels,370,371 polymers,372-377 and layered solids.378... 

Silica particles have been exploited in virtually every assay or detection strategy that polymer particles have been used in for bioapplication purposes. Recently, fluorescent dye-doped silica nanoparticles have been developed by a number of groups that have similar fluorescence characteristics to quantum dot nanocrystals (Chapter 9, Section 10). Fluorescent silica nanoparticles can be synthesized less expensively than quantum dots due to the fact that the silica particles incorporate standard organic dyes (Ow et al., 2005 Wang et al., 2006) and are not dependent on making reproducible populations of semiconductor particles with precise diameters to tune emission wavelengths. 

The disadvantages of organic dyes (low photostability, insufficient brightness, short lifetimes, etc.) have resulted in competition from luminescent metal-ligand complexes, semiconductor nanoparticles (Quantum Dots), and conjugated polymers. These new materials show advanced performance in a variety of applications... 

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