Optimization of the dye-sensitized solar cell with anthocyanin as photosensitizer

• Fabrication conditions to optimize DSSCs based on anthocyanin were searched.
• The efficiency is boosted to over 1.4%, almost triple the previously reported values.
• The copigments associated with anthocyanin contribute greatly to the performance.

Dye-sensitized solar cells (DSSC) were fabricated using anthocyanin extracted from red cabbage (Brassica oleracea var. capitata f. rubra), and the conditions that could maximize their performance were explored. The best light-to-electricity conversion efficiency (η) was obtained when the pH and the concentration of the anthocyanin extract were at 8.0 and 3 mM, respectively, and when the immersion time for fabricating sensitized TiO2 film was 15 min. Fabricating the DSSC in the presence of a coadsorbent, deoxycholic acid, at a molar ratio of dye:coadsorbent of 1:40 was also found to be able to improve the η significantly. The highest η reached was over 1.4%, which is almost three times higher than previously reported conversion efficiencies. In addition, the copigments associated with anthocyanin were found to contribute significantly to the performance of DSSC, and further purification of the anthocyanin extract led to a lower η.