NOVELTY - A solution is prepared (300) using cadmium-containing solute(s), sulfur-containing solute(s), water, and chosen material(s). The solution is loaded (320) into a pyrolysis-deposition system including nozzle(s) and heater (s). A substrate is placed (330) in the system and heated (350). The solution is sprayed (370) towards the substrate and a cadmium-sulfide layer is formed from the sprayed solution on the substrate. The chosen material is non-polar, has at least higher volatility than water, and/or has at least lower heat capacity than water.    USE - Formation of cadmium-sulfide layer on substrates used for photovoltaic modules e.g. solar cells.    ADVANTAGE - The method improves the material utilization by 80-95%. The addition of alcohol helps control the locations of the gasification of solutes between the spray nozzle and substrate surface, reduces clogging of spray nozzles, increases the dielectric constant of pyrolysis solution, and improves the charging properties of droplets of sprayed pyrolysis solution.    DETAILED DESCRIPTION - A solution is prepared using cadmium-containing solute(s), sulfur-containing solute(s), water, and chosen material(s). The solution including the chosen material is loaded into a pyrolysis-deposition system including nozzle(s) and heater (s). A substrate is placed in the pyrolysis-deposition system, and the distance between substrate and nozzle(s) is adjusted (340). The substrate is heated by the heater(s). The solution is sprayed towards the substrate and a cadmium-sulfide layer is formed from the sprayed solution on the substrate. The chosen material is non-polar, has at least higher volatility than water, and/or has at least lower heat capacity than water. An INDEPENDENT CLAIM is included for system for forming calcium-sulfide layer on substrate.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart of the formation method of thin film on substrate using spray pyrolysis solution.    Preparation of pyrolysis solution (300)    Loading of pyrolysis solution into pyrolysis system (320)    Placing of substrate (330)    Distance adjustment (340)    Substrate heating (350)    Spraying process (370)