Efficiency and high-temperature response of dye-sensitized solar cells using natural dyes extracted from Calotropis

The United Arab Emirates (UAE) enjoys abundant solar radiation with high ambient temperature. A high operating temperature for photovoltaics is therefore expected in this region. The applications of the third generation dye-sensitized solar cells (DSSCs) are currently hindered by the high production costs associated with the synthetic ruthenium-based dyes. Furthermore, the performance of most DSSCs considerably drops at elevated cell temperature which is disadvantageous to applications in the region. Natural dyes extracted from the native desert plants in the UAE offers a potentially attractive alternative: not only are the dye production costs much lower, but also the fact that native plants are well adapted against high temperature may lead to enhanced temperature response when using the corresponding photosensitizers in DSSCs. Here, DSSCs utilizing a natural dye extracted from the leaves of Calotropis have been manufactured and studied. Calotropis is a genus of widespread native plant in the UAE. The Optical characterizations revealed that the Calotropis dye shows better visible absorption compared to a chlorophyll-based reference dye from spinach leaves. Indeed, when incorporated into DSSCs, the cell made from the Calotropis sensitizer offered higher efficiency at room temperature. At elevated temperatures, remarkably, the Calotropis cell also demonstrated improved temperature response compared to the reference spinach cell. Consequently, this study shows that natural sensitizers from the native desert plants may offer a cost-effective approach to photovoltaic applications against the unique challenges of hot climate and harsh conditions highly relevant to the Gulf region.