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Title: Synthesis of phthalocyanines for dye sensitized solar cells and stabilised pigment systems
Author: Rugen-Hankey, Sarah
Awarding Body: Swansea University
Current Institution: Swansea University
Date of Award: 2010
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This thesis reports the synthesis of novel phthalocyanine based photosensitizers for DSSC devices. Key precursors, halogenated phthalonitriles have been synthesised and characterised, which included a novel periodic acid method for forming 4,5-diiodophthalonitrile. Phthalonitrile derivatives with functionalities were synthesised from halogenated phthalonitriles via palladium cross coupling reactions. A novel fumaronitrile anchoring group was synthesised from commercially available methyl 4-(cyanomethyl)-benzoate along with the literature compound 4,5-bis(4-methoxycarbonylphenyl) phthalonitrile. Negishi coupling of 1,1'-dibromo- and ethynylerrocene compounds to halogenated phthalonitriles are also described and characterised along with the synthesis of the solubilising group nonoxyphthalonitrile. The effectiveness of the subphthalocyanine and statistical cyclotetramisation routes to phthalocyanine synthesis using the substituted phthalonitiles has been investigated in the preparation of substituted azapoiphyrines and unsymmetrical phthalocyanines. The dyes contained different donor (r-butyl and nonoxy) and acceptor (carboxylic acid) functional groups, especially designed for sensitisation in DSSC devices. Ring expansion reaction of the subphthalocyanines was very dependent on the substituent and reaction conditions and, in many cases, was not a selective process. Statistical cyclotetramisation of mixed substituted phthalonitriles formed pseudo statistical mixtures where it proved hard to separate the individual compounds from each other. Both the substituted azaporphyrines and unsymmetrical phthalocyanine dyes were used to sensitise naonparticular titiania and constructed into DSSC devices, in which IV and IPCE curves have been measured for each dye. DSSC photoactivity was observed for each unsymmetrical substituted dye. This thesis also describes the synthesis and characterisation of magnesium-aluminium layered double hydroxide clays which, in turn, were used in the preparation of phthalocyanine-suppoited and phthalocyanine-intercalated layered double hydroxides. These substituted clays were then used for the preparation of stabilised pigment systems and were incorporated into model paint formulations based on a PVC matrix. Degradation studies were earned out using the CO2 Flat Panel Reactor using UV irradiated panels coated with the paint formulations. The effect of clay particle morphology, clay particle size, clay-pigment preparation method and pigment loading concentration were all investigated with results showing that > 5 % pigment loading was required to reduce PVC degradation rates. Reflectance measurements were also used to monitor degradation of the panels.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Eng.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available