We investigated flexible Ag nanowire (NW) network electrodes fabricated by simple brush-painting for cost-efficient FOSCs. By direct brush-painting Ag NWs on a PET substrate, we achieved Ag NW network electrodes with a low sheet resistance of 38.7 Omega/square and a high diffusive transmittance of 87.62% as well as superior mechanical flexibility. The electrical, optical, and mechanical properties of the brush-painted Ag NW electrodes were investigated as a function of the number of repeated brush-painting cycles. Identical performances of the FOSC with the brush painted Ag NW network electrode to those of the FOSC with a conventional ITO electrode demonstrate that the brush-painted Ag NW electrode is a promising alternative to ITO films for cost-efficient FOSCs. Furthermore, simple brush-painting is a low-cost and simple coating process to fabricate solution-based simple transparent electrodes. (C) 2012 Elsevier B.V. All rights reserved.