Drawing Inspiration from Nature for Solar Energy Conversion
Treat, Nick Treat
MetadataShow full item record
Photophysical properties of betalain pigments from beets (Beta vulgaris L.), amaranth (Amaranthus cruentus) and pitahaya (Hylocerus polyrhizus) were studied in the context of dye-sensitized solar cells. Utilizing a nature-inspired approach to solar energy production, natural pigments were extracted, purified and studied to develop a greater understanding of the light harvesting systems. The highly efficient light harvesting of the betalains, which is due to their photoprotective role in the plants, far surpasses the metalorganic dyes commonly used in dye-sensitized solar cells. Evidence of two-electron oxidation, and ease and abundant supply make betalain pigments an ideal candidate for a renewable energy solution. A process for the extraction and purification of mixtures and pure betalains was developed based on exchange chromatography and high performance liquid chromatography. The ability to perform experiments on samples with single betalain components allowed for more precise quantification of the feasibility and performance of betalain-based devices. Differences in the behavior of the dyes were used to develop a map of the structure-function relationships within betalain pigments. Betanin was shown to aggregate on TiO¬2 where amaranthin is not. The aggregate formed by betanin greatly enhanced the performance and stability of the devices. The fluorescence quantum yields of betalains were shown to also depend on structure, despite the distance between the additional acyl groups and the chromophore.