Preparation and photoelectric characteristics of CdS/TiO₂ compound nanoarray

TiO₂ nanorod arrays film was prepared on FTO by a simple hydrothermal synthesizing method. The formation of CdS quantum dots (QDs) sensitized TiO₂ nanorods was carried out by sequential chemical bath deposition (S-CBD) technique. The morphologies, phase structure, and optical absorption properties of the as-prepared materials were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and UV-vis spectrometer. The results indicate that the length of TiO₂ nanorods array is up to 2.9 μm and the diameters of CdS quantum dots range from 5 nm to 9 nm. With the increase of the sedimentary layers, the thickness of the CdS QDs increases, accompanied by the red shift of the absorption edge. By analyzing the photocurrent-voltage characteristics from I-V curve, it can be found that the photocurrent and photoelectric conversion efficiency both increase first and then decrease. A photocurrent of 2.49 mA·cm^-2, an open circuit photovoltage of 1.10 V, and a conversion efficiency of 1.91% are obtained under an illumination of 100 mW/cm², when the CdS QDs deposites on TiO₂ nanorod arrays film for about 7 cycles.