Optimization of single-crystal rutile TiO2 nanorod arrays based dye-sensitized solar cells and their electron transport properties

TiCl4 solution growth has been introduced to modify the single-crystal rutile TiO2 nanorod arrays (TNRs) used as photoanodes of dye-sensitized solar cells (DSSCs). After modification, a large number of rutile TiO2 nanoparticles have been synthesized on the surface of TNRs. The surface area and dye adsorption of these modified TNRs increase obviously, and their photovoltaic performance improves significantly. The maximum energy conversion efficiency of 4.14 +/- 0.07% has been obtained when the concentration of TiCl4 solution is 0.2 M and the growth time is 36 h. To obtain similar energy conversion efficiencies the single-crystal TNRs based DSSCs need far less amount of dye than P25 TiO2 nanoparticles based DSSCs. Contrary to previous publications, the electron transport rate of bare and modified single-crystal rutile TNRs with one-dimensional nanostructures is slower than that of P25 TiO2 nanoparticles film. But the increase of the electron recombination lifetime of the bare and modified single-crystal rutile TNRs compensates for the slower electron transport rate, and makes them have similar charge-collection efficiencies to that of P25 TiO2 nanoparticles based DSSCs. (C) 2013 Elsevier B.V. All rights reserved.