Abstract
Highly ordered nanoporous and nanotubular TiO2 geometries can be anodically grown on Ti substrates in fluoride containing ethylene glycol electrolytes using different water contents. Here we fabricate 1 pm thick layers consisting of arrayed tubes or pores with an open diameter of 15 nm. We compare these small diameter structures to classical 100 nm diameter TiO2 nanotubes for their application in Gratzel-type solar cells. The results show clearly that a small diameter nanotube geometry significantly enhances the solar cell conversion efficiency. (C) 2011 Elsevier B.V. All rights reserved.