TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Properties: The electrolyte layer of dye sensitizing solar cell consists of mixed solvent of hydrophobic ionic liquid which contains 1% or more of aprotic polar solvent. The aprotic polar solvent has boiling point of 100degreesC or more. Preferred Compounds: The conductive polymer used in dye sensitizing solar cell contains 3,4-ethylene dioxythiophene or its derivative(s). The hydrophobic ionic liquid contains bis(fluoro sulfonyl) imide of formula (1), or bis(trifluoromethane sulfonyl) imide of formula (2) as anion. EXAMPLE - Transparent electro-conductive film which consists of tin oxide doped with fluorine was formed on a transparent base which consists of glass by vacuum deposition. Then, a porous titanium-oxide semiconductor film having thickness of 15 microns was formed on the transparent electro-conductive using TSP-18NR (RTM: titanium-oxide paste having particle size of 20 nm) and TSP-400C (RTM: titanium-oxide paste having particle size of 400 nm). Then, the formed porous titanium-oxide semiconductor film was immersed in ethanol solution containing 0.4 mmol/L of N719dye (RTM: bis(4-carboxy-4'-tetrabutyl ammonium carboxy-2-2'-bipyridine) diiso thiocyanate ruthenium complex), and air-dried to obtained semiconductor electrode. Then, 1-ethyl-3-methyl imidazolium-bis(trifluoromethanesulfonyl) imide, propylene carbonate having boiling point of 242degreesC, iodine (0.2 mol/L), 1-methyl-3-propyl imidazolium iodine (2 mol/L), and 4-t-butyl pyridine (0.5 mol/L) were mixed to obtain electrolyte liquid of electrolyte layer. Then, poly (3,4-ethylene dioxythiophene) and poly (hydroxymethyl 3,4-ethylene dioxythiophene) were coated on glass to form counter electrode. Then, transparent electro-conductive film, porous titanium-oxide semiconductor film, semiconductor electrode, electrolyte layer and counter electrode were assembled to form photovoltaic cell. The obtained photovoltaic cell had excellent photoelectric-conversion-efficiency and durability.