This Progress Report highlights recent developments in dye-sensitized solar cells composed of both liquid electrolytes and solid-state hole transport materials. The authors discuss and review the present understanding of and recent developments in the operational processes, such as charge generation, transport, recombination, and E charge collection. Also, the merits and challenges of alternative device approaches are discussed, including extremely thin absorber cells, devices containing inorganic p-type hole-transporters and non-TiO2 mesoporous metal-oxide electrodes employed in dye-sensitized solar cells.