Performance evaluation of ruthenium complexes and organic sensitizers in ZnO-based dye-sensitized solar cells

Ruthenium (Ru) dyes are a well-known player in the field of dye-sensitized solar cells (DSSCs) due to their high efficiency and excellent stability. Their properties and complexes have been studied for almost three decades. Although these sensitizers show better performances, their high cost makes these third-generation solar devices less economical. Organic dyes have recently been explored as an alternative to Ru-based dyes due to their easy and low-cost synthesis. A comparative performance evaluation of Ru complexes and dicyanoisophorone and rhodanine organic dyes in ZnO-based DSSCs is here reported. All the Ru complexes showed better performance in comparison to organic dyes except R-4. Among the Ru sensitizers, R-3 exhibited the highest efficiency of 1.21% followed by R-2, which is attributed to the presence of several anchoring groups such as carboxyl, nitro and amine. However, the presence of more nitrogen-based groups has drastically reduced the performance as observed for R-4, which is the least performing dye among the Ru-based ones. On the contrary, organic sensitizers S-06 and P-4 revealed to be less efficient with respect to R-3 owing to the presence of only one anchoring group and weak photoanode/dye interaction.