In this work a water soluble derivative of polythiophene, namely (poly[3-(sodium-6 hexanoate)thiophene-2,5-diyl]) is used as photosensitizer and hole conductor instead of the liquid electrolyte, resulting in a solid state polythiophene-sensitized solar cell. The dense titania hole-blocking layer and the nanoporous TiO2 network are also prepared using a new water based method. The presented aqueous synthesis procedure for the photosensitizer, electron and hole conductor demonstrates the possibility to develop fully 'green' solid-state solar cells. (c) 2007 Elsevier B.V. All rights reserved.