This study investigated the influence of sputtering power and selenization on the thickness of the MoSe2, as it relates to the performance of Cu(In,Ga)Se-2 (CIGS) thin film solar cells with a structure of glass/Mo/CIGS/CdS/i-ZnO/ZnO: Al/Al. When the sputtering power exceeded 200 W (power density of 4.4 W/mm(2)) or the selenization temperature exceeded 773 K, the MoSe2 layer underwent a significant increase in thickness. The use of higher sputtering power to deposit the Mo contact resulted in superior Mo crystals and facilitated the formation of MoSe2 layers with hexagonal close-packed crystal structure during the selenization process. The thickness of the MoSe2 layer did not increase with soaking time during selenization. The highest device efficiency was obtained when the thickness of the MoSe2 layer was 240 nm. (C) 2014 Elsevier B. V. All rights reserved.