Vertically aligned, reasonably dense, about 500 nm long TiO2 nanotubes (NTs) are prepared on transparent conducting fluorine-doped tin oxide (FTO) surfaces by a wet chemical procedure. The dye-sensitized solar cells (DSCs) fabricated using such active electrodes and N719 dye with usual I-/I-3(-) electrolyte yield 2.46% solar-to-electricity conversion efficiency (eta) without the TiCl4 treatment and 3.40% with the TiCl4 treatment, both at 1000 W m(-2) simulated AM 1.5 irradiation. These values are higher and impressive for shorter NT arrays of similar to 500 nm length. The successive introduction of TiO2 nanoparticles (NPs) by spraying into the NTs to form NT-NP composite films results in a linear increase of dye coverage. The variation of eta as a result of NT-NP composite structure (with TiCl4 treatment) shows a gradual increase up to 8.53% at 1:2.2 NT:NP mass ratio, beyond which it slowly decreases. (C) 2012 Elsevier Ltd. All rights reserved.