For use in hybrid solar cells consisting of TiO2 and poly[2-methoxy, 5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEH-PPV), a TiO2 nanostructure which has periodic hexagonal hole arrays was fabricated using surface relief gratings on azobenzene-functionalized polymer films as a template in the sol-gel reaction of a Ti-precusor. The ordered bulk heterojunction solar cells, prepared with the TiO2 nanostructure and MEH-PPV, have a higher power conversion efficiency of 0.21% compared to bilayer and random bulk heterojunction solar cells fabricated with thin-dense TiO2 films and randomly networked TiO2 nanoparticles, respectively, under one sun with air mass 1.5 global illumination. (C) 2007 Elsevier B.V. All rights reserved.