NOVELTY - Poly(2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene) (MDMO-PPV) capped lead sulfide quantum dot is prepared by dissolving MDMO-PPV into toluene; making the obtained solution into an orange transparent solution; dissolving lead acetate powder into the solution; dissolving thioacetamide into dimethylsulfoxide; under a violent magnetic blending condition, slowly dripping the solution containing thioacetamide into the solution containing lead acetate; then generating more dark red flocculent precipitate in the solution; and then processing the precipitate.    USE - Method for preparing poly(2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene) (MDMO-PPV) capped a lead sulfide (PbS) quantum dot (claimed). The MDMO-PPV capped PbS quantum dot is used for preparing an MDMO-PPV capped PbS nanometer-sized rod material used for preparing a complex heterojunction solar battery.    ADVANTAGE - The method obtains the MDMO-PPV capped PbS quantum dot with a photoelectric application prospect. It has a simple operation and low cost.    DETAILED DESCRIPTION - Preparation of poly(2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene) (MDMO-PPV) capped lead sulfide (PbS) quantum dot, includes:    (A) dissolving the MDMO-PPV into toluene to form an orange translucent solution;    (B) under a magnetic blending condition, dissolving dimethylsulfoxide (3 ml) into the solution to make the solution into an orange transparent solution;    (C) adding lead acetate powder into the orange transparent solution to dissolve the powder under a supersonic condition;    (D) dissolving thioacetamide (12 mg) into dimethylsulfoxide (3 ml) on the magnetic blending condition;    (E) under a violent magnetic blending condition, slowly dripping the solution containing thioacetamide into the solution containing lead acetate;    (F) after 10-30 minutes, adding anhydrous ethanol into the reaction liquid to end the reaction to generate more dark red flocculent precipitate in the solution; and    (G) separating the flocculent precipitate using a centrifuge, washing with anhydrous ethanol, and drying at room temperature to obtain the MDMO-PPV capped PbS quantum dot.    INDEPENDENT CLAIMS are included for: (1) a method of preparing an MDMO-PPV capped PbS nanometer-sized rod material, including the first six steps of the method of preparing the (MDMO-PPV) capped lead sulfide (PbS) quantum dot; transferring the dark red flocculent precipitate to a high-pressure tank with a Teflon(RTM: PTFE) container, sealing the tank, putting the tank into a roasting box, reacting for 20-30 hours at 150-180 degrees C and, after ending the reaction, cooling to room temperature; and adding anhydrous ethanol (60 ml) into the reacted solution to generate more dark red flocculent precipitate, separating the flocculent precipitate using the centrifuge, washing with anhydrous ethanol, and drying at room temperature to obtain the MDMO-PPV capped PbS nanometer-sized rod material; and (2) a method of preparing a complex heterojunction solar battery formed by compounding the MDMO-PPV capped PbS nanometer-sized rod material and the MDMO-PPV, including the steps of the method for preparing the MDMO-PPV capped PbS nanometer-sized rod material; washing a glass respectively with a cleaning agent, deionized water, acetone, isoacetone under supersonic and roasting conditions; dissolving dimethylsulfoxide into poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and, at 60 degrees C, treating for 30-60 minutes by supersonic to fully dissolve it; applying the PEDOT:PPS solution to dry an indium tin oxide (ITO) glass to form a PEDOT:PPS thin layer with a thickness of 70-80 nm; transferring the glass with PEDOT:PPS into the roasting box after annealing, and putting it into a glove box full of nitrogen; dissolving the MDMO-PPV capped PbS nanometer-sized rod material into the MDMO-PPV chlorobenzene solution to treat by supersonic to make it disperse uniformly; transferring the MDMO-PPV solution with PbS nanometer-sized rod into the glove box and applying it on the glass with PEDOT:PPS; annealing the ITO glass under the protection of nitrogen; and transferring the annealed sample into a vacuum evaporating platform and, on a highly vacuum condition, evaporating an aluminum electrode, where the obtained sample is the inorganic-organic complex heterojunction solar battery.