CdS/CdSe Quantum dots Co-sensitized TiO2 Nanowire/Nanotube Solar Cells with Enhanced Efficiency

Translucent TiO2 nanowires/nanotubes (TiO2 NW/NT) film would be a promising candidate in constructing photoelectrochemical solar cells for its advantages in sensitizer loading, charge separation, electronic transport and light harvesting. In this report, translucent TiO2 NW/NT film was prepared by a two-step anodization method. The formation mechanisms of nanowires originated from nanotubes were explored. The hydrogen ions generated by electrolysis of water were driven by electric field to form ions flow, which altered the interfacial stress of nanotubes, resulting in vertically or spirally splitting the mouth of nanotubes to form nanowires. The CdS, CdSe and CdS/CdSe quantum dots (QDs) sensitized TiO2 NW/NT solar cells were constructed. Among them, The TiO2 NW/NT solar cells co-sensitized with CdS/CdSe QDs showed higher efficiencies than ones sensitized with CdS or CdSe QDs. By varying successive ionic layer adsorption and reaction (SILAR) cycles of CdS/CdSe, it was found that CdS(9)/CdSe(6)/TiO2 NW/NT device reached to a maximum power conversion efficiency of 2.41%, which was 78.5% higher than that of the CdS(9)/CdSe(6)/TiO2 NT solar cell. The excellent photoelectrochemical properties of our solar cell suggest that the translucent TiO2 NW/NT films co-sensitized with CdS and CdSe QDs have potential application in photovoltaic cells.