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ZnO-SiO 2 nanocomposite thin films were prepared using the target-attached RF sputtering method without substrate heating. The PL measurements showed that the SiO 2 films containing uniformly dispersed ZnO nanoparticles emit white light consisting of violet, blue, and green-yellow band emissions. The presence of the blue emission is attributed to the large number of ZnO/SiO 2 interfaces, which enlarges the depletion layer width and then enhances the related transition. The Gaussian curve fitting of PL spectra revealed that the competition between the blue and green-yellow band emissions and the relative emission intensity is strongly associated with the number of ZnO nanoparticles embedded in the SiO 2 matrix. XPS analysis revealed that the main component of the oxygen defect species in the ZnO nanocomposite thin films is 'O − ' ions (531.1-531.7 eV) at the subsurface. Within the knowledge of the defect configuration, XPS data were also utilized to estimate the oxygen vacancies and the specific carrier concentration in ZnO nanoparticles and relate to the integrated intensities of emission bands. Further analyses indicated that the defect structure of samples could be manipulated by the number and distribution of ZnO nanoparticles in SiO 2 matrix to yield a distinct luminescence spectrum.

We analyze the correlation between nanostructure and charge transport in poly(2-methoxy,5-(2'ethyl-hexyloxy)-p-phenylene vinylene) (MEH-PPV) films. The MEH-PPV films prepared in toluene (TL) as well as chlorobenzene (CB) solvents were investigated using the time-of-flight method and x-ray scattering. Nondispersive hole transport was observed at room temperature in devices prepared from both solutions. The field and temperature-dependent mobility were analyzed by the Gaussian disorder transport model. The positional disorder parameter in CB is larger than that in TL films. Both energy and position disorders affect the transport property in the devices from CB whereas only energy disorder affects this property in devices from TL. Correspondingly, according to the x-ray scattering measurements, the TL-cast films have larger chain-packed domains and less order-disorder transition interfaces than those for CB-cast films, along the surface normal, i.e., the charge transport direction

ZnO quantum dots (QDs)-SiO2 nanocomposite films were prepared using the target-attached radio-frequency sputtering. The transmission electron microscopy revealed the uniform dispersion of ZnO QDs with diameters about 2–7nm in amorphous SiO2 matrix. The photoluminescence showed that small ZnO QDs are able to emit white light with luminescence spectra similar to those of the present GaN-based light emitting diode (LED). The calculated chromaticity coordinates of emitting light evidenced the feasibility of ZnO QDs-SiO2 nanocomposite films as the fluorescence material in optoelectronic devices.

CdS nanoparticles with surfaces modified by mercaptoethanol have been synthesized for greater solubility in dimethylformamide (DMF) and the ability to preferentially bind to the poly(ethylene oxide) (PEO) blocks of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymer. The size of the surface-modified CdS nanoparticles (M-CdS) in DMF can be characterized by the Schultz distribution of a mean radius of 18.4 Å and a polydispersity of 0.5, using small-angle X-ray scattering (SAXS). These M-CdS nanoparticles can further disperse in the PS-b-PEO, with a slightly larger mean radius than that observed in DMF. The uptake of M-CdS nanoparticles for the PEO blocks of the PS-b-PEO saturates around 7% in volume fraction. The binding of the nanoparticles promotes a segregation of the PEO/ nanoparticles and leads to spherical PEO/M-CdS microdomains in the composite film with a greatly enhanced thermal stability. The structural information obtained from X-ray scattering agrees well with the transmission electron microscopy images and differential scanning calorimetry results.