NOVELTY - An ionic liquid electrolyte is a composition obtained by mixing ionic liquid of di(fluorosulfonyl)imide ion (1) and iodide ion, and iodine, or a composition obtained by mixing ionic liquid of di(fluorosulfonyl)imide ion and iodide ion, iodine and other ionic liquids, additive, curing agent and reagent. The ionic liquid comprising iodide ion is formed of iodide and organic cation. The cation of other ionic liquid is organic cation. The anion is halogen ion, polyhalide ion, nitrate ion, isothiocyanate ion, tetrafluoroborate ion, sulfonate ion or sulfate ion.    USE - Ionic liquid electrolyte is used for dye-sensitized solar cell.    ADVANTAGE - The ionic liquid electrolyte provides dye-sensitized solar cell having excellent photoelectric power conversion efficiency.    DETAILED DESCRIPTION - An ionic liquid electrolyte is a composition obtained by mixing ionic liquid of di(fluorosulfonyl)imide ion and iodide ion, and iodine, or a composition obtained by mixing ionic liquid of di(fluorosulfonyl)imide ion and iodide ion, iodine and other ionic liquids, additive, curing agent and reagent. The ionic liquid comprising iodide ion is formed of iodide anion and organic cation. The cation of other ionic liquid is organic cation. The anion is halogen ion, polyhalide ion, nitrate ion, isothiocyanate ion, tetrafluoroborate ion, amine-containing ion (-N(CN)2), cyano-containing ion (-C(CN3)), boron-containing ion (-B(CN)4), trifluoromethanesulfonate ion, trifluoroacetate ion, bistrifluoromethylsulfonyl imide ion, hexafluorophosphate ion, tris(trifluoromethylsulfonyl)methanide ion, sulfonate ion (RSO3-) or sulfate ion (RSO4-). The ionic liquid electrolyte contains additive, curing agent and reagent. The additive is chosen from guanidine salt, lithium salt, sodium salt, potassium salt, cesium salt, magnesium salt or compound without charge and having nitrogen atom comprising isolated electron pairs. The curing agent is nano-silicon dioxide, nano-titanium dioxide, nano-aluminium oxide, nano-magnesium oxide, carbon nanotube and its derivates, fullerene and its derivates or graphite and its derivates. The reagent is acetonitrile, valeronitrile, methoxylpropionitrile, furan or polymer such as polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-hexafluoropropylene-chlorotrifluoroethylene copolymer, polyamide, polypyrrole, polythiophene, polystyrene, polybutadiene rubber polyethylene oxide, polymethyl methacrylate, polyacrylonitrile or polythiophene and their derivates. The ratio of ionic liquid comprising di(fluorosulfonyl)imide ion and ionic liquid comprising iodide ion is 10:1-1:5. The ratio of iodide and ionic liquid electrolyte comprising iodide ion is 1:50-1:2. The ratio of other ionic liquid and ionic liquid comprising iodide ion is 20:1-1:2. The ratio of additive and ionic liquid comprising iodide ion is 1:100-1:10. The ratio of curing agent and ionic liquid comprising iodide ion is 20:1-1:20. The ratio of reagent and ionic liquid comprising iodide ion is 10:1-1:80. The di(fluorosulfonyl)imide ion is of formula: A+(N(SO2F)2)- (1).    A+=organic cation;and    R=H, or linear or branched alkyl.