ARGONNE NATIONAL LABORATORY
CHEMICAL SCIENCES AND ENGINEERING
DIVISION SEMINAR
SPEAKER: Michael Walter
Portland State University
TITLE: Amino/Carboxyphenyl Porphyrin Syntheses and Applications in Polyaniline TiO2 Dye-Sensitized and Bulk Heterojunction Polyporphyrin/Fullerene Solar Cells
DATE: Monday Morning
October 1, 2007
TIME: 10:00 am
PLACE: Building 200, J-183
HOST: David Tiede
Abstract: Meso-substituted tetraphenylporphyrins containing both aminophenyl and carboxyphenyl substituents (TAxCyPPs) have been synthesized for use in solid-state (polyaniline) dye-sensitized TiO2 solar cells (DSSCs). Carboxyphenyl substituents anchor the porphyrin dye to the surface of the TiO2 while aminophenyl groups form covalent connections to a photoelectrochemically grown polyaniline hole conductor layer. DSSC devices constructed with TAxCyPPs have shown efficiencies of up to 1% under AM 1.5 simulated solar illumination. Mixed substituent porphyrins containing two or more aminophenyl groups can also be electrochemically polymerized to form thin conductive films with variable film surface nanomorphology. The electrochemical oxidation of the tetramino derivative (tetrakis-5,10,15,20-(4-aminophenyl)porphyrin, TAPP) leads to a conductive polymeric film (poly-TAPP) with a nanostructured fibrous morphology. The film morphology and growth rate are enhanced by the presence of pyridine in the electrochemical solvent and by the use of a constant potential delay at the oxidizing end of the cyclic voltammetry sweeps. By filling the nanoporous porphyrin film with an electron acceptor material such as TiO2 or fullerene derivative (PCBM), an inverse dye-sensitized solar cell device structure can be realized. Initial results of donor/acceptor photovoltaic devices constructed in this manner using poly-TAPP films and PCBM/TiO2 have shown reasonable photovoltaic activity.