Degree Name

Master of Science (MS)

Semester of Degree Completion

2016

Thesis Director

Hongshan He

Abstract

It is predicted that more than 20 terawatts of carbon-free energy will be demanded by 2050 to maintain a sufficient energy supply for the increasing global population, and photovoltaics are predicted to contribute significantly to the global energy needs. Dye-sensitized solar cells (DSCs) are an emerging class of photovoltaics (PV) that has produced promising power conversion efficiencies at low costs. Currently, electron recombination, dye aggregation, weak adsorption, and inefficient absorbance are among of the largest contributors to low DSC efficiencies.

BODIPY dyes are one of the most promising classes of dyes emerging for DSC application. These low molecular weight fluorophores produce narrow absorption bandwidths with high extinction coefficients. These properties allow for efficient sunlight absorption and cost effect DSC construction. Furthermore, the absorbance and emission spectra are highly susceptible to substituents introduced to the BODIPY core.

In this study, five BODIPY dyes with a donor-(π-spacer)-acceptor arrangement have been designed to address the current challenges. Two dyes, HS10 and MH13, were successfully synthesized and studied. Both HS10 and MH13 combined a 4-ethynyl-N,N-dimethylaniline electron donor group and a cyano-3-(4-ethynylphenyl)-2-propenoic acid acceptor. MH13 which employed a 2,6-dihexyloxybenzene substituent at the meso position of the BODIPY core, produced a power conversion efficiency of 1.75%, significantly higher than the 0.77% efficiency of its mesityl-substituted analogue (HS10). The dye loading density for MH13 was more than triple that of HS10. The absorption coefficients were identical for both dyes, and MH13 produced a λmax that was red-shifted by only 3 nm relative to HS10.

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