In this paper, the influence of reducing the thickness of the CIGSe absorber layer by bromine etching from 2.5 mu m to 0.5 mu m on electrical and optical solar cell properties is addressed. We observe a decrease in efficiency which is mainly caused by a reduced short circuit current, whereas the fill factor and the open circuit voltage are stable. Even without deliberate light trapping or anti-reflection coating, an efficiency of 10.3% is obtained for a 0.5 mu m thick CIGSe absorber. A smoothing of the absorber surface is observed during the etching, its influence on the cell parameters will be discussed. (C) 2011 Elsevier B.V. All rights reserved.