Novel fatty acid-ionic liquids for photovoltaic thermal management

The growing global energy demand, combined with the limitations of fossil fuels, highlights the need for renewable energy technologies with improved efficiency and stability. Among renewables, solar photovoltaic cells are widely used, but their performance declines at elevated temperatures, making effective thermal management essential. In this study, we explore fatty acid-ionic liquids as novel phase change materials for passive cooling of photovoltaic cells. A series of new fatty acid-ionic liquids was synthesized by pairing the 1-methyl-3-octadecylimidazolium cation with fatty acid anions such as octanoate, nonanoate, decanoate, and dodecanoate via a metathesis reaction. Structural confirmation was achieved using spectroscopic analyses while thermal properties were characterized through thermal analyses. The fatty acid-ionic liquids exhibited melting points between 43 °C to 60 °C, within the operational range of photovoltaic modules, and demonstrated high enthalpies of fusion (154.5–245.1 J/g) and good thermal stability up to 150 °C. The fine tuning observed in thermal properties of the fatty acid-ionic liquids results from the increase in their anion alkyl chain length. A miniature solar cell test system was custom-built, incorporating photovoltaic cells, cuvettes, thermocouples, and a solar simulator, and the performance of the fatty acid-ionic liquids was evaluated. The results indicate that fatty acid-ionic liquids can potentially overcome problems of many traditional phase change materials and be fine-tuned for moderating photovoltaic cell temperatures, thus improving their efficiency and extending operational lifespan.