Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.651370
Title: Transition metal complexes as solar cell dyes
Author: Geary, Elaine A. M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2005
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Abstract:
Dye-Sensitised Solar Cells (DSSC) were first reported in the early 1990’s and function by the sensitisation of a semiconductor using a dye molecule such as organic and transition metal organometallic dyes. This thesis reports the synthesis and characterisation of transition metal dyes with applications as sensitisers in DSSC. Complexes of Ni, Pd and Pt were investigated for use in standard liquid electrolyte cells and Donor-Acceptor type solid-state solar cells. A family of [Pt(II)(diimine)(dithiolate)] complexes of general formula [Pt{X,X’(CO2R)2-bpy}(mnt)] (where X=3, 4 or 5; R=H or Et, bpy = 2,2’-bipyridyl and mnt = maleonitriledithiolate), have been synthesised, spectroscopically and electrochemically characterised and attached to a TiO2 substrate to be tested as solar cell sensitisers. A single crystal X-ray structure showing a large torsion angle between the bipyridyl rings was determined for [Pt{3,3’(CO2Et)2-2,2’-bpy}(mnt)].MeCN. The effect of changing the position of the bpy substituents from 3,3’ to 4,4’ and 5,5’ is discussed with reference to structural and electronic changes seen within the different members of the family of molecules. The UV/Vis/NIR and in-situ EPR spectroelectrochemical studies of the family and its related precursor molecules are discussed. All three complexes (where R=H) were tested as solar cell sensitisers with the 3,3’-disubstituted bpy complex giving an intermediate dye loading value but superior photovoltaic performance to those of the other two. The performance of this sensitiser is then compared with that of a well known Ru(polypyridyl) sensitiser. A family of unsymmetrical [Ni(II)(dithione)(dithiolate)] complexes of general formula, [Ni(R1R2pipdt)(dmit)], where R = Me, Bz and Pri, pipdt = 1,4-disbustituted-piperazine-3,2-dithione and dmit = 1,3-dithiole-2-thione-4,5-dithiolate, have been synthesised and characterised and investigated for use in solid-state solar cells. electrochemistry and UV/Visible spectroscopy results show that the reduction potential of a complex is related to the number of aromatic substituents on the pipdt ligand. The dibenzyl substituted complex shows the largest absorption wavelength in the NIR which is attributed to it having the smallest HOMO-LUMO gap of the complexes studied. In-situ EPR results show the reduction electron to be located on the R1R2pipdt ligand which confirms previous proposals that the LUMO is in part located on this part of the complex. Raman spectroscopy confirms the dmit ligand to be formally dianionic with the R1R2pipdt having a formally neutral charge.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.651370  DOI: Not available
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