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A very cheap solvent, ethanol, was successfully applied to control ZnO crystal growth for fabricating a series of ZnO composite nanostructures. During the experimental process, a two-step chemical route was adopted. In step-one, ZnO nanowire arrays were grown on fluorine-doped tin oxide coated glass substrate. In step-two, the step-one prepared samples were used as substrates for composite nanostructure deposition. The morphologies of the obtained products were characterized by field emission scanning electron microscopy. The results indicate that the morphologies of the final products can be effectively controlled by changing the water/ethanol ratios in the chemical solution. The obtained ZnO composite nanostructures with various morphologies were successfully employed in dye-sensitized solar cells. The light-to-electricity conversion results show that the composite nanostructures consisting of nanowires and pseudospherical nanostructures enable 80% improvement in solar energy conversion efficiency as compared with the nanowire arrays. These results indicate that the synthesized ZnO composite nanostructures are more suitable for application as photoelectrodes in solar cells.

In order to improve the performance of ZnO-based solar cells, ZnO/CdS core/shell heterostructures were synthesized via a facile chemical conversion route. Large area and quasi-aligned ZnO nanowire arrays were firstly fabricated on conductive glass substrates, and then the synthesis of ZnO/ZnS and ZnO/CdS heterostructures were realized by a chemical conversion method. The morphology and structure of the obtained products has been confirmed by field-emission scanning electron microscopy and X-ray diffraction measurements. The synthesized ZnO/CdS core/shell heterostructures were successfully applied in solar cells. The photovoltaic performance investigation demonstrates that the synthesized ZnO/CdS heterostructure-based solar cell shows a higher short-circuit current density compared with the N719 dye-sensitized ZnO nanowire array counterpart. The enhancement in current density may be due to the fact that the surface coverage of the light absorption layer in the ZnO/CdS core/shell heterostructure is very high. These results indicate that the synthesized ZnO/CdS heterostructures by the present method are very suitable for the application as photoelectrode in solar cells.

CdO nanowires and nanotubes have been synthesized by the two-step temperature-controlled thermal evaporation process without any catalyst. The results demonstrate that CdO nanowires synthesized by vapor–solid mechanism grow along the [1 1 1] direction and their surface is surrounded by polyhedron-shaped CdO nanocrystals. The formation of nanocrystals should be attributed to the existence of dangling bonds in the sidewall of nanowires. We also successfully synthesized CdO nanotubes and deduced their formation mechanism. The difference of growth orientation for nanotubes and nanowires should be most likely linked to processes of nucleation and growth. Furthermore, energy-dispersive X-ray spectrum and X-ray diffraction analysis also testify that the synthesized nanowires and nanotubes have face-centered cubic CdO structures and possess good crystallinity.

Rare earth complex Eu(phen)2Cl3·2H2O synthesized by precipitation method was incorporated into MCM-41 mesoporous molecular sieves which were synthesized via a hydrothermal method. Hybrid inorganic/organic mesoporous luminescent material Eu(phen)2/MCM-41 has been characterized by XRD, TEM, IR, UV-visible spectra and fluorescence spectra. Results indicated that the hybrid mesoporous material has typical structure of MCM-41 and retains the same pore structure as MCM-41 after the assembly process. The fluorescence spectra of these materials present a series of narrow lines assigned to 5D0 → 7F0,1,2,3,4 transitions. The high emission intensity observed is a promising property for application of the rare earth complex in technological luminescent devices.

Ge doped ZnO films have been deposited on Si(1 0 0) substrates by alternate rf sputtering of ZnO and Ge. The effects of doping and annealing on the optical and structural properties have been investigated by means of X-ray diffraction and photoluminescence (PL) spectra. With the increasing annealing temperature, the intensity of the ZnO(0 0 2) diffraction peak increases, indicating that the crystalline quality of the film improves. The samples annealed at 800 and 1000 °C there appear the GeO and GeO2 diffraction peaks, and the intensity of the near ultra-violet emission at 395 nm increases greatly, while a weak yellow emission appears at 590 nm. The near ultra-violet emission could be attributed to the GeO color centers and exciton recombination. The yellow peak is probably related to Ge incorporated in the ZnO structure.