TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Component: The porous layer comprises metallic oxide particles having a mean particle diameter of less than or equal to100, preferably 10-40 nm. It comprises particles from conductive particles or light scattering particles. The first electrode comprises a conductive film (12) coated on the substrate.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The first conductive film is indium tin oxide, fluorine tin oxide, zinc oxide-gallium oxide, zinc oxide-aluminum oxide, or tin oxide-antimony oxide and a second conductive film from platinum or precious metals. The dye materials of the composite dye comprise metal complex from aluminum complexes, platinum complexes, palladium complexes, europium complexes, lead complexes, iridium complexes or rubidium complexes.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Material: The dye material of composite dye comprises Ru(2,2':6'-2"-terpyridine-4,4',4"-tricarboxylic acid (NCS)3. Preferred Component: The Ru(2,2':6'-2"-terpyridine-4,4',4"-tricarboxylic acid (NCS)3 in the composite dye is 10-80 mol.%. The composite dye comprises Ru(2,2':6'-2"-terpyridine-4,4',4"-tricarboxylic acid (NCS)3 and Ru(4,4'-dicarboxy-2,2'-bipyridine)2(CN)2. The dye material of the composite dye comprises an organic pigment from coumarin, porphyrin, xanthene, riboflavin or triphenylmethane.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The first conductive film is indium tin oxide, fluorine tin oxide, zinc oxide-gallium oxide, zinc oxide-aluminum oxide, or tin oxide-antimony oxide and a second conductive film from platinum or precious metals. The dye materials of the composite dye comprise metal complex from aluminum complexes, platinum complexes, palladium complexes, europium complexes, lead complexes, iridium complexes or rubidium complexes.    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The first electrode comprises a transparent substrate (12, 21) from polyethylene terephthalate, polyethylene, polyimide, or triacetate cellulose. The porous layer comprises a polymer from polyethylene glycol, polyethylene oxide, polyvinyl alcohol or polyvinyl pyrrolidone.