<p>The interactions between the molecular constituents in dye-sensitized solar cells were studied with UV-VIS and IR spectroscopy, Raman scattering, conductivity and electron accumulation measurements.</p><p>From stability studies of the dye, bis(tetrabutylammonium)cis-bis(thiocyanato) bis(2,2’-bipyridine-4-carboxylic acid, 4’-carboxylate) ruthenium(II), in the complete solar cell, the thiocyanate ion ligand was found to be lost from the dye. A method was developed to study mechanisms in a sealed dye-sensitized solar cell using resonance Raman scattering (RRS). RRS studies of a complete dye-sensitized solar cell including iodine and lithium iodide in the electrolyte indicate that triiodide exchange the SCN<sup>-</sup> ligand of the dye. It was proposed that an ion pair Li<sup>+</sup>…I<sub>3</sub><sup>-</sup> formation occurred, which, by a reduced electrostatic repulsion between I<sub>3</sub><sup>-</sup> and SCN<sup>-</sup> facilitated the exchange of these anions at Ru(II) of the dye. The additive 1-methylbenzimidazole suppressed the SCN<sup>-</sup>/I<sub>3</sub><sup>-</sup> ligand exchange by forming a complex with Li<sup>+</sup>.</p><p>In order to study charge transport in nanostructured TiO<sub>2</sub> films permeated with electrolyte, a technique was developed for determining activation energies of conduction, electron accumulation and effective mobility. Two regions were distinguished from the relation between conductivity and electron concentration. In the first region (~1-20 electrons per TiO<sub>2</sub> particle), which resembles best the region where the nanostructured dye-sensitized solar cell operates, the results can be fitted to some extent with a trapping/detrapping or a hopping model for charge transport, but not with a conduction band model. For the second region (> 20 electrons per TiO<sub>2</sub> particle), charge transport by electrons in the conduction band seems to be the most applicable model.</p><p>Through this work many effects from the interplay between the solar cell components were observed. These observations emphasize the importance of well-balanced interactions in dye-sensitized solar cells.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-3752 |
| Date | January 2003 |
| Creators | Greijer Agrell, Helena |
| Publisher | Uppsala University, Department of Physical Chemistry, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X ; 901 |
Page generated in 0.0116 seconds