Using Raman spectroscopy in addition to electrochemical impedance spectroscopy, we have clarified the deteriorated components of dye-sensitized solar cells (DSCs) module after the longest durability test in the world under outdoor working condition for similar to 2.5 years. It was confirmed that the N719 dye-adsorbed TiO(2) electrode and carbon counter electrode were almost stable; therefore, the photocurrent (Jsc) was maintained during the outdoor working. The photovoltages (Voc) and the filling factors (FF) slightly decreased due to the increase of the Nernst diffusion impedance of triiodide (I(3)(-)), resulting from the change of the components in the electrolyte. (C) 2008 Elsevier B.V. All rights reserved.