TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The porous semiconductor layer contains nanoparticles of semiconductor(s) chosen from titanium oxide, zinc oxide, tin oxide, niobium oxide and molybdenum oxide, and having diameter of 10-30 nm. The thickness of porous semiconductor layer is 0.1-10 mu m. The counter electrode has thin film of platinum, and thin film of transparent conducting oxide chosen from tin-doped indium oxide and aluminum-doped zinc oxide.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The sensitizing dye includes organic dye (a) and organic dye (b) with different absorption largest wavelength. The organic dye (a) and organic dye (b) with different molecular size have alkyl side chain(s) in one molecule. The number of carbon atoms of alkyl side chain is 1-18. The organic dye (a) is of formula (I)-(III), preferably chosen from 29 compounds e.g. 2-((3-((5-carboxy-3,3-dimethyl-1-octyl-2,3-dihydro-1H-indol-2-ylidene)methyl)-4-(dicyanomethylidene)-2-oxidocyclobut-2-en-1-ylidene)methyl)-1,3,3-trimethyl-3H-indol-1-ium, 2-((3-((5-carboxy-3,3-dimethyl-1-octyl-2,3-dihydro-1H-indol-2-ylidene)methyl)-4-(dicyanomethylidene)-2-oxidocyclobut-2-en-1-ylidene)methyl)-1-ethyl-3,3-dimethyl-3H-indol-1-ium, 2-((3-((5-carboxy-3,3-dimethyl-1-octyl-2,3-dihydro-1H-indol-2-ylidene)methyl)-4-(dicyanomethylidene)-2-oxidocyclobut-2-en-1-ylidene)methyl)-3,3-dimethyl-1-octyl-3H-indol-1-ium, 2-((3-((5-carboxy-1,3,3-trimethyl-2,3-dihydro-1H-indol-2-ylidene)methyl)-4-(dicyanomethylidene)-2-oxidocyclobut-2-en-1-ylidene)methyl)-3,3-dimethyl-1-octyl-3H-indol-1-ium, and 2-((3-((5-carboxy-1-ethyl-3,3-dimethyl-2,3-dihydro-1H-indol-2-ylidene)methyl)-4-(dicyanomethylidene)-2-oxidocyclobut-2-en-1-ylidene)methyl)-3,3-dimethyl-1-octyl-3H-indol-1-ium. The organic dye (b) is chosen from 16 compounds e.g. (2E)-2-cyano-3-(5-((E)-2-(4-(diphenylamino)phenyl)ethenyl)thiophen-2-yl)prop-2-enoic acid, (2E)-3-(5-(2,2-bis(4-(diphenylamino)phenyl)ethenyl)thiophen-2-yl)-2-cyanoprop-2-enoic acid, (2E)-3-(5-((E)-2-(4-(bis(4-methylphenyl)amino)phenyl)ethenyl)thiophen-2-yl)-2-cyanoprop-2-enoic acid, (2E)-3-(5-((E)-2-(4-(bis(4-methylphenyl)amino)phenyl)ethenyl)thieno(3,2-b)thiophen-2-yl)-2-cyanoprop-2-enoic acid, and (2E)-2-cyano-3-(4-((E)-2-(4-(diphenylamino)phenyl)ethenyl)phenyl)prop-2-enoic acid.R1,R5=H or carboxy, where at least one of R1 and R5 is carboxy;R2,R4=1-180C (halo)alkyl;R3=O, malononitrile, cyanoacetic acid, cyanoacetic ester, barbituric acid or thiobarbituric acid;andR6,R7=phenyl or fluorenyl (optionally substituted by alkyl or alkoxyl).Preferred Properties: The value of performance index measured as product of visibility weighting integral transmittance and photoelectric conversion efficiency of transparent dye-sensitized solar cell is 150 or more. The maximum absorption wavelength of sensitizing dye (b) is 350-450 nm. The maximum absorption wavelength of sensitizing dye (a) is 650-1000 nm. The molecular size of organic dye (a) is more than molecular size of organic dye (b). The external quantum efficiency with respect to an ultraviolet light is more than external quantum efficiency with respect to an infrared-light. The external quantum efficiency with respect to ultraviolet light is 50% or more. The light transmittance of counter electrode in visible region of 380-780 nm is 70% or more. The haze rate in wavelength of 550 nm of component consisting of the electroconductive support component and porous semiconductor layer is 10% or less.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The counter electrode contains thiophene polymer, preferably polyethylene dioxythiophene. The carrier transport layer contains liquid electrolyte containing transparent oxidation reduction electrolyte. The carrier transport layer has a positive hole transport layer containing organic hole-transport material chosen from low-molecular arylamine derivative and polymer of arylamine, thiophene, benzothiadiazole and carbazole.