An oligothiophene bearing 1-hydroxy-1-oxodithieno[2,3-b:3',2'-d]phosphole (TP) as a novel anchoring group has been synthesized for dye-sensitized solar cells (DSSC). Attenuated total reflectance-Fourier transform infrared and X-ray photoelectron spectroscopy measurements disclosed the bidentate binding of the phosphinic acid unit to a TiO2 surface. A TP-sensitized TiO2 cell yielded a maximum incident photon-to-current efficiency of 66% and a power conversion efficiency of 1.8%, indicating that 1-hydroxy-1-oxodithienophosphole is a potential unit as a new type of anchoring groups for DSSC.