Mechanically stable mesoporous nanocrystalline titania thick films can be prepared at low temperature (100degreesC) by hydrothermal treatment of an aqueous mixed paste containing nanocrystalline TiO2 powder and Ti salts. The Ti monomers are converted into crystalline TiO2, which acts as a "glue" to chemically connect the TiO2 particles. Highly efficient flexible dye-sensitized solar cells prepared on a conductive plastic film substrate were realized using this method and a conversion efficiency of 2.3% at AM1.5 was achieved.