Asymmetrical squaraine sensitizers with varying π-bridges and anchoring groups for dye sensitized solar cells

Abstract

The work detailed in this thesis focuses on three separate projects. The first explored the effect of introducing conjugated π-bridges equipped with different solubilizing groups, and anchoring groups on the overall performance of asymmetrical squaraines; namely by enhancing their high energy absorption, reducing dye aggregation as well as electron recombination from the mesoporous TiO2 into the acceptors in the electrolyte. The second project looked into the effect of molecular iodine, a species that can be generated locally near the TiO2 surface, on enhancing unwanted electron recombination from TiO2 into the electrolyte. The synthesis of a squaraine-based dye containing a long, fluorinated alkyl chain, which have low binding affinity to iodine, positioned near the TiO2 surface can create a pseudo blocking layer which prevents acceptors in the electrolyte, namely molecular iodine, from capturing an injected electron from TiO2. The third project consisted of the incorporation of large, out-of-plane cyclic groups in the indole region of a donor- π-acceptor dye with the goal of studying the modification’s effect on dye spacing, aggregation, and possible excited state quenching.