Enhanced photostability of anthocyanin dye for increased efficiency in natural dye sensitized solar cells

To improve the performance of anthocyanin based dye sensitized solar cells (DSSC), it is essential to passivate the photocatalytic activity (PCA) induced by photoelectrode that activates dye degradation. In the present work, red color astaxanthin pigments extracted from green color Haematococcus Pluvialis is used as a cosensitizer with anthocyanins extracted from rose petals to scavenge the free radicals (antioxidant) generated as a result of PCA, thereby minimizing photodegradation of anthocyanins by 60 %. Herein we have hydrothermally prepared rutile TiO2 nanostructures that appear as distorted TiO2 nanospheres (NS) and the cosensitizer ratio is optimized for maximum astaxanthin efficacy. The least molecular interaction of astaxanthin with anthocyanins as measured from fluorescence life time studies suggest that astaxanthin encircle anthocyanins as a shield against photodegradation. The structure of DSSC with Fluorine doped Tin Oxide/TiO2 NS/algal buffer layer/cosensitized dye (Rose:Astaxanthin - 70 :30)/iodine-iodide/Pt/glass shows a higher efficiency of 2.82 %. Relatively higher efficiency of 3.31 % was also observed for DSSC with 3% Ca doped TiO2 nanorods as photoelectrode using cosensitized dye as sensitizer due to the passivation of PCA by the astaxanthins and the photoelectrode by itself.

Automated summary

The study demonstrates the use of a co-sensitizer to prevent photodegradation of anthocyanins caused by photocatalytic activity, with an optimized co-sensitizer ratio maximizing the efficacy of astaxanthin. This leads to an improvement in the efficiency of dye-sensitized solar cells.