A new layered photocathode with porous NiO nanosheets: an effective candidate for p-type dye-sensitized solar cells.

Herein, with the purpose of improving the efficiency of p-type dye-sensitized solar cells (DSSCs), a new layered photocathode (LP) is fabricated from irregular overlapping wrinkled porous NiO nanosheets. The LP was sensitized by using a commonly used dye, coumarin 343(C343), and then assembled into p-type DSSCs through coupling with a platinum photoanode. Photoelectochemical characterization showed that the LP cell exhibited a clearly enhanced power-conversion efficiency (by a factor of 4) compared with a cell with a NiO-nanoparticle photocathode (NP). This excellent performance could be attributed to the overlapping layered structure, which favored hole transport, as confirmed by electrochemical impedance spectroscopy, and to the large surface area of the porous NiO nanosheets, which were favorable for dye adsorption.