The performances of infrared-dye-sensitized solar cells fabricated using two novel cyanine dyes (light absorption edge: 900 nm) were investigated. The performance of the cell using NK6037 dye was superior to that using NK4432; hence, an intimate interaction between the dye and the TiO(2) photoelectrode via the functional group is essential for efficient electron injection. The efficiency reached 1.9% by optimizing the light-confining effect of the TiO(2) photoelectrode and TiO(2) film thickness, and reached 2.3% by adjusting the concentration of deoxycholic acid (DCA) in the dye solution. The roles of the dye and DCA were clarified by photochemical and electrochemical characterization. (C) 2008 Elsevier B.V. All rights reserved.