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International Journal of Photoenergy
Volume 2006 (2006), Article ID 23703, 8 pages
http://dx.doi.org/10.1155/IJP/2006/23703

Positively charged polysilsesquioxane/iodide lonic liquid as a quasi solid-state redox electrolyte for dye-sensitized photo electrochemical cells: Infrared, 29Si NMR, and electrical studies

1National Institute of Chemistry, Hajdrihova 19, Ljubljana 1000, Slovenia
2Engineering Science Department, University of Patras, Patras 26500, Greece

Received 25 February 2005; Accepted 5 January 2006

Copyright © 2006 Vasko Jovanovski et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A new sol-gel precursor based on 1-methyl-3-[3-(trimethoxy-λ4-silyl)propyl]-1H-imidazolium iodide (MTMSPI+I) was synthesized and investigated as a potential novel quasi solid-state ionic liquid redox electrolyte for dye-synthesized photoelectrochemical (DSPEC) cells of the Graetzel type. MTMSPI+I was hydrolyzed with acidified water and the reaction products of the sol-gel condensation reactions assessed with the help of 29Si NMR and infrared spectroscopic techniques. Results of the time-dependent spectra analyses showed the formation of positively charged polyhedral cube-like silsesquioxane species that still contained a small amount of silanol end groups, which were removed after heating at 200°C. After cooling, the resulting material formed is a tough, yellowish, and transparent solid, which could be reheated again and used for assembling DSPEC cells. The addition of iodine increased the specific conductivity of the hydrolyzed and nonhydrolyzed MTMSPI+I, which we attributed to the formation of triiodide ions contributed to the conductivity via the Grotthus mechanism. DSPEC cells based on a titania-dye system with MTMSPI+I electrolyte containing iodine (0.1 M) reached an overall efficiency between 3.3–3.7%.