TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The first composite particles and the second composite particles have a core-shell structure in which each seed particle is coated with the outer layer respectively. The first composite particles have a dentrite structure in which indium selenide is partially grown on a surface of the copper selenide seed particle, and the second composite particles have a dentrite structure in which copper selenide is partially grown on a surface of the indium selenide seed particle. Each outer layer of the first composite particles and the second composite particles is formed by adding each seed particle into a precursor solution for outer layer and then reacting it. The first composite particles are formed by adding copper selenide seed particles into a precursor solution for outer layer in which indium nitrate and selenous acid are dissolved in an organic solvent, and then reacting them. The copper selenide seed particles are formed using at least one of copper selenium (CuSe) and/or Cu2Se. The second composite particles are formed by adding indium selenide seed particles into a precursor solution for outer layer in which copper nitrate and selenous acid are dissolved in an organic solvent and then reacting them. Preferred Particle: In the composite particle, the outer layer is coupled to the surface of the seed particle in a core-cell structure or in a dentrite structure.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The organic solution is at least one or a mixture of at least two of diethylene glycol, 1,4-butanediol, polyethylene glycol, propylene glycol and polypropylene glycol. The paste is made by mixing the first or second composite particles with ethyl cellulose, polypropylene carbonate or polypropylene glycol acting as binders in a solvent selected from water, alcohol and glycol. EXAMPLE - Indium-selenium (In-Se) particles (2 g) were mixed as seed particles in 250 ml of a diethylene glycol solvent together with 2 g of copper nitrate and 2 g of selenous acid as reactant precursors. The reaction solution was heated to 170degrees C and reacted for about 3 hours to produce composite particles. Powder of the product mixture was mixed with terpineol as a solvent and polypropylene carbonate as a binder, and then made into paste. The paste was coated on a substrate, and then Rapid Thermal Annealing (RTA) was conducted at 480degrees C for 5 minutes in N2 atmosphere to make copper-indium-selenium (CuInSe) (CIS).