A method of preparing Cu(In,Ga)SSe2 Cu(In,Ga) (S,Se)2 (CIGSS) absorber layers uses coated semiconductor nanoparticle and nanowire networks. The nanoparticles and nanowires containing one or more elements from group IB and/or IIIA and/or VIA are prepared from metal salts such as metal chloride and acetate at room temperature without inert gas protection. A uniform and non-aggregation CIGS precursor layer is fabricated with the formation of nanoparticle and nanowire networks utilizing ultrasonic spaying technique. High quality CIGSS film is obtained by cleaning the residue salts and carbon agents at an increased temperature and selenizing the pretreated precursor layer.