TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: In the method (M1): the coating temperature is 150-290 degrees C, preferably 200-260 degrees C; and the reaction time is 1 minute to 4 hours, preferably 15 minutes to 2 hours. The method (M2) comprises washing the core/shell nanoparticles at least one time to remove the impurities. Preferred Components: The molar ratio of the alkanethiol is higher than of zinc salt, where the molar ratio of alkanethiol and zinc salt is 2-80:1. The alkanethiol is an alkanethiol with at least one of sulfhydryl functional groups, preferably 1-octanethiol, isooctanethiol, dodecanethiol, 1-tetradecanethiol, 1-hexadecanethiol, 1-octadecanethiol, 1,8-dioctylthiol or 1,6-dioctylthiol. The non-polar organic solvent is octadecene, dodecane, hexadecane, octadecane, Diphyl DT (RTM: Dimethyl diphenyloxides), Diphyl THT (RTM: Partly hydrogenated terphenyls), paraffin, diphenyl ether, dioctyl ether or dibenzyl ether. The organic solvent is methanol, ethanol, acetone, isopropyl alcohol or butanol. EXAMPLE - Zinc acetate (0.293 g) was mixed with dodecanethiol (3 ml) and octadecene (6 ml). The resultant mixture was then heated to 100 degrees C, and the temperature was maintained until the zinc salt was completely dissolved, to obtain the homogeneous solution as shell precursor solution. Then cuprous acetate (0.051 g), indium acetate (0.12 g) and dodecanethiol (1.03 ml) were mixed with octadecene (10.3 ml).The obtained mixture was then degassed and stirred for 30 minutes under a flow of nitrogen. The resultant mixture was then stirred at 240 degrees C for a predetermined stirring time, to obtain the solution of copper indium sulfide nanoparticles. Then the shell precursor solution was poured into the solution of copper indium sulfide nanoparticles, and the solution of copper indium sulfide/zinc sulfide core/shell nanoparticles was obtained after a predetermined reaction time, at 240 degrees C. The resultant solution was then cooled to room temperature to obtain the core/shell nanoparticles solution.