We report oil the fabrication of efficient annealing-free polymer solar cells via simple brush painting considered as a promising method for the mass production of organic devices based on the high-speed roll-to-roll system. Higher device efficiency could be obtained compared to the spin-coated devices, resulting from the improved organization of polymer chains and better balanced carrier transport induced by more effective application of shear stress to the polymer chains during the brushing process. In addition, fully brush painted solar cells, including the brush-painted PEDOT:PSS and photoactive layer, presented a high power conversion efficiency of 3.6% without ally annealing treatment and processing additives. (C) 2009 Elsevier B.V. All rights reserved.