Cu(In,Al)Se-2 (CIAS) thin films are expected as the absorber of high-efficiency solar cells similar Cu(In,Ga)Se-2 (CIGS).To realize high-efficiency CIAS solar cells, we attempted to deposit CIAS thin films using three stage evaporation process, which could realize the large crystal grain size and the V-shape band profiling. CIAS thin films with Al/(In+Al) composition ratios of 0.07-0.34 were prepared and the band gap energy was controlled from 1.10 to 1.38 eV. At low Al contents of Al/(In+Al)<= 0.21, a relatively large crystal grain size of 2 mu m was obtained, while that became small down to 0.5-1 mu m for Al/(In+Al)<= 0.27. As the band gap increases the voltage dependence of photocurrent increases, indicating a poor minority carrier collection. This behavior was similar to that of wide band gap CIGS solar cells (c) 2008 Elsevier B.V. All rights reserved.