Upright-standing SnO2 nanowalls: Fabrication, dual-photosensitization and photovoltaic properties

We report on fabrication of upright-standing SnO2 nanowalls aligned on FTO substrates by a facile wet chemical method at low temperature. These nanowalls are dual-photosensitized with CdS quantum dots and Z907 dye molecules in order to construct panchromatic dye-sensitized solar cells. We demonstrate that thin CdS quantum dot layer not only acts as a blocking layer preventing recombination of charge carriers, but also contributes as a light absorber. A 158% improvement in power conversion efficiency is observed, which is attributed to improved light absorption, reduced recombination and improved charge collection in presence of CdS quantum dot interlayer.