A new semiconductor electrode for sensitized liquid junction photovoltaic solar cells is demonstrated. By making use of chemical vapor deposition, a graphite substrate is covered with a nanostructured thin film consisting of whiskers of boron phosphide which are sensitized by amorphous boron subphosphide (BxP). To obtain the two different morphologies of boron phosphide, the partial pressure of the boron precursor is changed during chemical vapor deposition synthesis. The optical properties of amorphous BxP thin films on quartz substrates were investigated and it is found that the absorption edge is dependent on the boron content. Photocurrent action spectra of sensitized nanostructured films show a mobility edge of 1.5 eV, which is well below the absorption edge of 2.0 eV of crystalline boron phosphide.