Tandem dye-sensitized solar cell (DSSC)-electrochromic (EC) devices were realized using two-faced transparent conducting oxide (TCO). To supply sufficient voltage to drive the EC devices, two series connected, semitransparent DSSCs were fabricated with 7nm-thick, dye-adsorbed TiO 2 and 4nm-thick Pt layers. The two series connected, semitransparent DSSCs that were used had an open circuit voltage and short circuit current density of about 1.35V and 3.96mAcm −2 , respectively, at 1-sun. The tandem DSSC-EC devices showed an optical density difference of 1.2 at 750nm and reasonable response times of about 60 and 45s during the coloring and bleaching processes, respectively, indicating that the two series-connected, semitransparent DSSCs could be used as the power sources in the tandem photovoltaic-powered EC devices.