Growth of ZnO nanowires and their applications for CdS quantum dots sensitized solar cells

ZnO nanowires grown on ITO conductive glass substrates by chemical bath deposition (CBD) method were used as photoanodes to assemble the CdS quantum dots sensitized solar cells (QDSSCs). The growth mechanism of ZnO nanowires and the photovoltaic performance of CdS QDSSCs were investigated. The results show that the c-axis oriented seed layer and the growth process both contribute to the preferential alignment of ZnO nanowires along the [0001] direction. The average length and diameter of nanowires increase with increasing growth time, and the maximum aspect ratio is 20.56 at 9 h. CdS quantum dots deposited on ZnO nanowires enhance the absorbance and extend the absorption range to the visible region. ZnO nanowires with higher aspect ratio effectively increase the energy conversion efficiency (η) of CdS QDSSCs, and the best η is 0.401% with an aspect ratio of 20.56. In such a solar cell, the short-circuit current density is significantly improved due to more electron-hole pairs and strong light trapping effect of ZnO nanowires.