In order for dye-sensitized solar cells (DSCs) to be competitive with current technology, overall efficiencies of these systems must be improved. In this regard, the photosensitizing dyes in DSCs play a critical role by absorbing photons from sunlight and transferring electrons for current generation. However, use of a second dye dissolved in the electrolyte, known as an energy relay dye (ERD), has been shown to further enhance solar conversion efficiency by increasing the range of absorption of the solar spectrum. Recently, a new class of materials known as a Group of Uniform Materials Based on Organic Salts (GUMBOS) were examined as ERDs. GUMBOS are solid phase, typically amorphous, organic salts composed of bulky organic ions with melting points from 25°C to 250°C. The properties of GUMBOS have been shown to be tunable through variations in the counter-ion, resulting in materials with tunable characteristics different from the parent compounds. We have previously shown that by use of counter-ions commonly employed in ionic liquids, we can improve the solubility of GUMBOS in the electrolyte, as well as provide better flexibility in optical properties. In the study described here, GUMBOS are synthesized using rhodamine-, cyanine-, and porphyrin-based dyes. Studies of the optical properties of these compounds using ultraviolet-visible absorbance spectroscopy and fluorescence spectroscopy were performed. Solar efficiencies were evaluated in the presence of multiple ERDs using N719 as the photosensitizing dye. DSCs in the presence of multiple GUMBOS-based ERDs were found to have increased solar efficiencies as compared to those with only one ERD present. This study gives further insight into the importance of the counter-ion used in GUMBOS synthesis and its relationships to a change in solar efficiency, as well as demonstrates that multiple ERDs can significantly improve photovoltaic performance.

Optimizing multiple energy relay GUMBOS dyes for dye-sensitized solar cells

255th National Meeting (2018)

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