Titanium dioxide (TiO2) nanostructures are widely employed in photoconversion processes. In particular titanium dioxide nanotubes (TNTs) have shown promise in many applications including solar cells. While there are methods for making TNT films the preparation of high surface area small diameter (<10nm) TNT films is a challenge. We have now prepared TNT films by pulsed laser deposition (PLD) of P25 and P90 TiO2TiO2 nanoparticles onto stainless steel foils followed by a hydrothermal treatment. The best results were obtained when the TiO2TiO2 films were deposited at 500°C. Subsequent hydrothermal treatment at 150°C results in a dense mat of TNTs that are ˜10 nm in diameter with a pore size of ˜5 nm. The TNTs were further functionalized with quantum dots including PbS with controlled particle size and location to access a greater portion of the solar spectrum. The titanium oxide nanotube/ quantum dot films were characterized by SEM, TEM, XRD UV-Vis and Raman spectroscopy. Preliminary results for the formation and characterization of solar cells using the TNT films will be described.

Cost benefit analysis (CBA) and energy profit ratio (EPR) indicate that third generation PV should be high-throughput ones with higher efficiency than CdTe PV. The polymer photovoltaics (OPV) such as PCBM/P3HT, and the dye-sensitized solar cells (DSC), i.e. TiO2/dyes/iodide-iodine-electrolytes will be reviewed as printable PV to cope in near future with environmentally benign PV demand. The recent progress of OPV and DSC will be discussed in terms of diffusion length, and our recent studies on iodine-free DSC. The OPV-DSC-hybridized PV exemplified by solid-state Dye/TiO2/P3HT will become hopeful as printed thin-film solar cells, in particular when the conversion efficiency is further enhanced more than 10%.