Large-area integrated modules of flexible plastic type dye-sensitized solar cell (DSC) have been fabricated based on polyethylene naphthalate (PEN) film for practical applications such as ubiquitous power sources. From the view point of improving durability, composition of organic solvent-based electrolytes has been investigated. As a result, a plastic DSC module using Lil-free electrolyte maintained its energy conversion efficiency of 2% over 220 h under the accelerated condition of 55 degrees C and 95% relative humidity. (C) 2008 Elsevier B.V. All rights reserved.