The photoexcited electrons transfer dynamics of the CdS quantum dots (QDs) deposited in TiO2 nanowire array films are studied using surface photovoltage (SPV) and transient photovoltage (TPV) techniques. By comparing the SPV results with different thicknesses of QDs layers, we can separate the dynamic characteristics of photoexcited electrons injection and trapping. It is found that the TPV signals of photoexcited electrons trapped in the CdS QDs occur at timescales of about 2 x 10(-8) s, which is faster than that of the photoexcited electrons injected from CdS into TiO2. More than 90 nm of the thickness of the CdS QDs layer will seriously affect the photoexcited electrons transfer and injection. (C) 2014 AIP Publishing LLC.

Single crystal TiO2 nanorod arrays grown on FTO substrate were prepared by hydrothermal method. The morphology, structure and photoelectric property were investigated with scanning electron microscope (SEM), X-ray diffraction spectrum (XRD), ultraviolet-visible absorption spectrum (UV-Vis) and surface photovoltage spectrum(SPS), respectively. In the contraction of different arrays with different substrates we found that the FTO substrate had a decisive effect on the growth of nanorod arrays. The lattices of TiO2 seed layer and SnO2: F matched very well, which helped the epitaxial growth and the orientation of nanorod arrays. According to the field induced surface photovoltage spectroscopy, there was a band upward bending in TiO2 nanorods at the interface of TiO2 and FTO. Introducing seed layer into the process of growth can help the orientation of array, decrease the interface state greatly and provide the potential to increase the collection efficiency of carrier.

The thin copper films were deposited by magnet sputtering on fluorine-doped tin oxide (FTO) coated glass. The CuO nanowires array film can be obtained through the heat oxidation process. The morphology and microstructure of the copper film and the CuO nanowires film was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM), respectively. The CO and H 2 S sensing characteristics of the CuO nanowires array film were also investigated. The results show that CuO nanowires array film exhibited highest response to CO gas at 250°C. The response was significantly enhanced when the CO gas concentration was increased. There is a sensing response at low gas concentration for H 2 S at room temperature. While for the higher temperature, the resistance of the CuO nanowires array film decreased rapidly, which is different from the CO gas. The abnormal resistance change for the H 2 S was also illustrated in this article.

Well-aligned CdS/TiO2 nanotube array composite film was fabricated on the indium-doped tin oxide(ITO) substrate by templating ZnO nanorod array film.The effects of CdS deposition time on the morphology,crystal structure,photo-electric properties of TiO2/CdS composite film were investigated via scanning electron microscopy(SEM),X-ray diffraction(XRD),ultraviolet-visible absorption spectrum(UV-Vis) and surface photovoltage spectrum(SPS).The results showed that the absorbance of composite film extended to the visible region compared with the pristine TiO2 nanotube arrays.The SPS also showed a new response region relative to the absorption spectrum.This result indicated a remarkable photo-electric conversion efficiency improvement in the visible region.We also found that the SPS response intensity of composite film decreased gradually in the visible region with the increase of CdS deposition time.We interpreted and discussed this phenomenon using distinct photo-induced charge generation and transfer mechanisms detailedly.Despite this,we also discussed the influence of surface-to-volume ratio on the final photo-electric properties for the CdS/TiO2 nanotube array composite film.