Electro-spray (e-spray) is emerging as an attractive printing method because of its simple apparatus and high productivity for the thin-film fabrication of conjugated polymer materials. We report here a study of the e-spray deposition conditions of highly conductive poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) films. The highest conductivity of 800 S/cm was achieved by independently optimizing the process parameters such as the solvent dilution ratio, the amount of additive, and the substrate temperature. Although the conductivity was largely governed by the morphologies of the deposited films, we found that in e-spray deposition, pure electrical scattering (irrespective of the specific morphology) also influenced the macroscopic conductivities. Using the optimized e-spraying conditions, we fabricated a top PEDOT:PSS electrode for a semitransparent inverted organic solar cells (OSCs) without any performance degradation in the underlying photoactive layer. (C) 2011 Elsevier B.V. All rights reserved.