Preparation of Double Dye-Layer Structure of Dye-Sensitized Solar Cells from Cocktail Solutions for Harvesting Light in Wide Range of Wavelengths

Dye-sensitized solar cells (DSCs) consisting of a double dye-layer structure of Ru dye (Z907) and organic dye (NK3705) were prepared by dipping porous titania substrates into dye mixture solutions. Dye structures such as NK3705 were crucial for realizing the double layer structure. A porous titania layer adsorbed NK3705 predominantly in the dye mixture. The adsorbed NK3705 was then replaced by Z907 from the top to the bottom of the porous titania surface as a function of dipping time. The DSCs based on the double dye-layer structure were able to harvest light in a wide range of wavelengths.