NOVELTY - A polymer electrolyte comprises mixture (A), organic solvent (B), oxidation-reduction electric pair comprising iodine/potassium iodide in molar ratio of 1:5-1:10, plasticizer and crosslinker. The mixture (A) comprises polyoxyethylene and vinylidene fluoride hexafluoropropylene copolymer in weight ratio of 1:4-4:1. The total weight of the mixture (A) in the polymer electrolyte is 2-10 wt.% with respect to the weight of organic solvent (B). The organic solvent (B) comprises propylene carbonate and ethylene glycol dimethyl ether in volume ratio of 1:8-8:1.    USE - Polymer electrolyte is used for dye-sensitized nanocrystalline solar cell (claimed).    ADVANTAGE - The polymer electrolyte has excellent ionic conductivity due to the presence of plasticizer and crosslinker. The dye-sensitized nanocrystalline solar cell obtained using the polymer electrolyte has excellent photoelectric conversion efficiency, reduced dark reaction ratio, and improved open circuit voltage and short circuit.    DETAILED DESCRIPTION - A polymer electrolyte comprises mixture (A), organic solvent (B), oxidation-reduction electric pair comprising iodine/potassium iodide in molar ratio of 1:5-1:10, plasticizer and crosslinker. The mixture (A) comprises polyoxyethylene and vinylidene fluoride hexafluoropropylene copolymer in weight ratio of 1:4-4:1. The total weight of the mixture (A) in the polymer electrolyte is 2-10 wt.% with respect to the weight of organic solvent (B). The organic solvent (B) comprises propylene carbonate and ethylene glycol dimethyl ether in volume ratio of 1:8-8:1. The molar ratio of potassium of the oxidation-reduction electric pair and oxygen of the polyoxyethylene is 0.6-0.8. The content of plasticizer and crosslinker is 10-30 wt.% and 25-125 wt.%, respectively with respect to the total weight of the mixture (A). The crosslinker is aprotic solvent solution having concentration of 0.05-0.10 g/ml thiourea. An INDEPENDENT CLAIM is included for preparation of polymer electrolyte.