TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: In the method a ternary core or a ternary first shell is respectively used, and the molecular ratio of metal precursors in the core reaction mixture of step (a) is (1-2):(1-2), where the anion precursor is in excess. The reaction mixture of step (c) is cooled before the step (d). The core size and shell thickness respectively are varied by way of adjusting concentration and concentration ratios of precursor materials, ligand types and solvents and process parameters including temperature, temperature ramps, order and dynamics of addition of precursors. The shell growth is allowed to proceed until the outer shell shows a thickness of 0.3-4 nm of pure shell material. The zinc sulfide shell is prepared with a thickness of 0.3-4 nm of pure shell material and is obtained by repeating steps for zinc sulfide shell preparation. The method is conducted in a microreactor system comprising elements including micromixers for mixing steps, residence microreactors for reaction steps or a micro heat exchanger for cooling step, where micromixers and residence reactors also comprise micro heat exchangers and elements are connected with each other so the reaction mixture flows continuously from one to the next element. Preferred Components: The semiconducting core-shell nanoparticle comprises a zinc sulfide shell having a thickness of 0.3-4 nm of pure shell material. EXAMPLE - Copper(I) iodide (26.6 mg), indium(III) acetate (40 mg), 1-octadecene (19.7 ml) and dodecanethiol (0.3 ml) were added in a 3-neck round bottomed flask, degassed for 5 minutes and purged with nitrogen. The solution was rapidly heated up to 220 degrees C under nitrogen for 45 minutes to get the copper indium sulfide core particles with a quantum yield of 11%. Then zinc acetate (1207 mg), 1-octadecene (83 ml), dodecanethiol (16 ml), oleylamine (11 ml) and tri-n-octylphosphine (11 ml) were added into a 3-neck round bottomed flask, degassed for 30 minutes and purged with nitrogen. The solution was heated up to 100 degrees C under nitrogen for 30 minutes and cooled to dissolve chemicals until a transparent shell precursor solution was formed. Then shell precursor solution (30 ml) was added to the core solution and stirred, degassed, purged with nitrogen. The solution was continued to heat to 230 degrees C and held for 75 minutes and cooled to obtain the copper indium sulfide/zinc sulfide core/shell particles having a quantum yield was 81%.