Coarsened TiO₂ nanoparticles generated from basic titanate precursors

TiO₂ is a favored electron acceptor for composite photovoltaic solar cells. The n-type semiconductor has a wide band gap and favorable alignment of the conduction band relative to the excited states of interfacial visible light "sensitizers". Mesoporous anatase yields architectures that greatly enhance interfacial areas between the oxide and sensitizers (dyes, inorganic semiconductors, or polymers). However, a compromise must be established between increased surface area for very small nanoparticles and reduced interfacial charge carrier recombination for larger nanoparticles. A low-temperature route for nanoparticulate alkylammonium titanate suspensions has been developed for the precursor materials. These precursors were then subjected to hydrothermal coarsening, converting the titanates to anatase (TiO₂) with larger dipyramidal nanoparticle morphologies. The materials were compared with sol-gel derived anatase nanoparticles. Powders of the materials were characterized by XRD, FTIR, SEM, and nitrogen absorption. Porous films were deposited on transparent conductive oxides to determine photocurrent onset potentials relative to SCE.