2-Ethyl-1-hexanol based screen-printed titania thin films for dye-sensitized solar cells D.S. Tsoukleris a , I.M. Arabatzis a , E. Chatzivasiloglou a , A.I. Kontos a , V. Belessi a , M.C. Bernard b , P. Falaras a, * a Institute of Physical Chemistry, NCSR ‘‘Demokritos’’, 153 10 Aghia Paraskevi, Athens, Greece b UPR 15 du CNRS ‘‘Physique des Interfaces et E ´ lectrochimie’’, Universite ´ Pierre et Marie Curie, 75252 Paris Cedex 05, France Received 21 July 2004; received in revised form 3 November 2004; accepted 23 February 2005 Available online 30 March 2005 Communicated by: Associate Editor Sixto Malato-Rodrı ´guez Abstract Nanocrystalline titania thin films were prepared by screen printing in order to efficiently control and optimize the main step of the dye-sensitized solar cells (DSSCs) fabrication process. Different compositions of nanocrystalline tita- nium dioxide screen-printing pastes are described, based on 2-ethyl-1-hexanol solvent and commercial Degussa P25 TiO 2 . The rheological properties of the prepared pastes are presented as the crucial parameter of the deposition pro- cedure. The produced titania thin films are extensively characterized by means of spectroscopy (Raman, XRD) and microscopy (SEM, AFM). The performance (induced photon-to-current efficiency—IPCE% and overall energy conver- sion efficiency—g%) of the corresponding DSSCs is also reported. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: TiO 2 thin films; Screen printing; Dye-sensitized solar cells 1. Introduction During the last decade, extensive studies have been carried out on the preparation and characterization of large band gap, n-type, thin film semiconductors such as TiO 2 , due to their application in solar energy-conver- sion processes. Photosensitization of nanocrystalline wide band gap semiconductors has emerged as a prom- ising low-cost alternative to traditional photovoltaic technologies (OÕRegan and Gra ¨tzel, 1991; Gra ¨tzel, 2003; Hagfeldt and Gra ¨tzel, 1995; Smestad, 2002). In contrast to the all-solid conventional semiconductor solar cells, the dye-sensitized solar cell (DSSC) is a pho- toelectrochemical cell, in which the anode consists of a transparent conducting glass coated with a nanocrystal- line TiO 2 thin film, where electronic conduction is insured by an expanded network of nanosized intercon- nected particles (Kamat and Meisel, 1996). The thick- ness of the film varies from several hundred nanometers up to 8–10 lm. Ruthenium(II) complex dye molecules are chemisorbed through functional anchoring groups (carboxylic acid or phosphonic acid) on the surface of the semiconductor. The pores of the film are filled with an electrolyte containing a redox 0038-092X/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.solener.2005.02.017 * Corresponding author. Tel.: +30 210 6503644; fax: +30 210 6511766. E-mail address: papi@chem.demokritos.gr (P. Falaras). Solar Energy 79 (2005) 422–430 www.elsevier.com/locate/solener