Date of Award
Chemistry and Biochemistry
Four D-π-A dyes based on a 3,4-thienothiophene Ï€-bridge were synthesized for use in dye-sensitized solar cells (DSCs). The pro-aromatic building block 3,4-thienothiophene has been reported to stabilize dye excited-state oxidation potentials. This lowering of excited-state energy levels permits for increased absorption into the near-infrared (NIR) region using relatively low molecular weight dyes. Strong donor functionality based on triaryl- and diarylamines are employed in the dye designs to raise both the ground and excited-state oxidation potentials to values capable of generating DSC devices with good open-circuit voltages. Solubility, aggregation, and TiO2 surface protection were addressed by examining an ethylhexyl alkyl chain in comparison to a basic ethyl chain on the thienothiophene bridge. Through this minor structural modification, a drastic increase in overall efficiency of up to 7.8% is observed. Again in an attempt to stabilize dye excited-state oxidation potentials through competing local aromaticity, a fifth dye was synthesized to incorporate a pro-aromatic indolizine-based donor moiety. Preliminary optical and electrochemical results with regards to the indolizine-based dye appear to be undesirable in terms of prospective cell performance. These preliminary results are believed to stem from the excessively strong electron withdrawing tricyanofuran acceptor unit seen in this dye.
Puneky, George A., "Pro-Aromatic Dye Components for Dye-Sensitized Solar Cells: Thienothiophene and Indolizine" (2015). Honors Theses. 347.