CIGS films were prepared on Mo-coated glass by sputtering and selenization processes. The metallic precursors were selenized under higher pressure in selenium vapor instead of H2Se. In order to improve the performance of CIGS thin film solar cells, the morphologies of CIGS thin films were studied carefully by various temperature profiles. The relationship between temperature decrease rate and fill factor (FF) of solar cells was investigated thoroughly. On the other hand the value of open circuit voltage (V-oc) was improved by increasing the gallium content near the surface of CIGS thin film. A glass/Mo/CIGS/CdS/ZnO cell was fabricated and the conversion efficiency of 9.4% was obtained without antireflective film. (c) 2005 Elsevier Ltd. All rights reserved.