P-type and pn-type dye-sensitized solar cells

In view of the scientific issues lying behind (1) the p-type dye-sensitized solar cells (DSCs) (the limited dye loading on the NiO film and serious charge recombination between the reduced dyes and the holes generated in the NiO) and (2) pn-type DSCs (mismatching of photoanode and photocathode), we review the recent progress of the electrodes, dyes, and electrolytes for these types of solar cells. The feasible solution of these issues is discussed and, at last, the future development of these types of solar cells is prospected.