We have investigated the effect of In diffusion on the electronic structure of a polyethylenedioxythiophenepoly (styrenesulfonate) layer deposited on InSn(x)O(1-x) substrate by photoelectron spectroscopy. We observe additional states near the highest occupied molecular orbital of the polymer layer that are generated by In releases from the substrate. Also, we observe that In diffusion continues into an overlayer of a mixture of poly (3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester. On the basis of the results of the numerical line shape analysis of In 3d(5/2) core level emission, we rule out the presence of metallic In clusters within the organic layers and suggest instead that In/sulfur compounds are present within the organic layers. (C) 2011 Elsevier B.V. All rights reserved.