Dye solar cells without electrolyte or hole-transport layers: a feasibility study of a concept based on direct regeneration of the dye by metallic conductors

Flat structures consisting of dense dye-sensitized TiO2 films with various materials for dye regeneration (TiO2/dye/regeneration material) are compared. Au and PEDOT:PSS were tested as metal or metal-like regeneration materials and compared with reference compounds, such as the redox couple I-/I-3(-) in solution and p-type CuSCN. Under the exclusion of TiO2 bandgap excitation, the short-circuit photocurrent densities for the various structures differ by less than similar to 30%, suggesting comparable charge separation efficiencies. The good performance of a metallic regeneration material implies, that the frequently assumed requirement of p-type or 'hole conducting' properties for the regeneration material in solid state dye solar cells is questionable. Copyright (c) 2005 John Wiley & Sons, Ltd.