NOVELTY - Producing lead (Pb(Pb))-chalcogenide nanoparticles involves: preparing and mixing Pb precursor and chalcogen element precursor, and carboxylic acid in hydrocarbon solution, to obtain mixture having predetermined Pb:chalcogen element ratio; injecting mixture into nucleation and growth solution containing surfactant, and heating to nucleate Pb-chalcogenide nanoparticles; cooling solution to growth temperature below nucleation temperature and holding for predetermined time, to achieve desired nanoparticle size; and cooling to below growth temperature to terminate nanoparticle growth.    USE - For producing Pb(Pb)-chalcogenide nanoparticles (claimed), useful for producing semiconductive materials for manufacturing solar cells, thermoelectric devices, telecommunication equipment, field effect transistors and biological imaging.    ADVANTAGE - The method provides an improved method for controlling the properties of a Pb-chalcogen material, by controlling the shape and size of nanoparticles of the material. The method controls the shape and size of the nanoparticles by selecting an appropriate surfactant, Pb:chalcogen element ratio, temperature of reaction, and time of reaction. The Pb:chalcogen ratio determines the shape of the Pb-chalcogenide nanoparticles (preferably the Pb:chalcogen element ratio is 1:5-5:1). The surfactant in the form of a phosphonic acid or an amine determines the shape of the Pb-chalcogenide nanoparticles. The use of phosphonic acid also controls the size of the Pb-chalcogenide nanoparticles, such that phosphonic acid having a longer hydrocarbon chain produces nanoparticles of a smaller size; when compared to nanoparticles produced using a phosphonic acid with a shorter hydrocarbon chain. The selection of a growth solvent from diphenyl ether (DPE) or trioctyl phosphine (TOP) controls tie shape of the Pb-chalcogenide nanoparticles. Also the controlling the size of the nanoparticles is achieved by selecting a predetermined growth temperature (preferably 100-200 degrees C) and/or growth time (preferably 2-10 minutes).    DETAILED DESCRIPTION - Method for producing Pb(Pb)-chalcogenide nanoparticles involves:    (A) preparing a Pb precursor containing a Pb compound and a carboxylic acid dissolved in a hydrocarbon solution of formula (R)n-X;    (B) preparing a chalcogen element precursor containing a chalcogen element dissolved in the hydrocarbon solution, where the amount of the chalcogen element dissolved in the hydrocarbon is such that the precursors are present at a predetermined Pb:chalcogen element ratio, when the Pb precursor is mixed with the chalcogen precursor;    (C) mixing the Pb precursor with the chalcogen element precursor to make a Pb-chalcogen mixture having the predetermined Pb:chalcogen element ratio;    (D) preparing a nucleation and growth solution containing a surfactant, and heating the nucleation and growth solution to a nucleation temperature to nucleate Pb-chalcogenide nanoparticles, when the Pb-chalcogen mixture is added;    (E) injecting the Pb-chalcogen element mixture into the nucleation and growth solution, so that the nucleation and growth solution causes Pb-chalcogenide nanoparticles to nucleate;    (F) cooling the Pb-chalcogenide nanoparticle solution to a growth temperature that is below the nucleation temperature;    (G) holding the Pb-chalcogenide nanoparticle solution at the growth temperature for a predetermined time period, such that a desired nanoparticle size is obtained; and    (H) cooling the Pb-chalcogenide nanoparticle solution to a temperature below the growth temperature, such that continued growth of the Pb-chalcogenide nanoparticles is terminated.    R=2-12C alkyl, or 6-12C aryl;    n=2, or 3;    X=O, or P.