Investigations on the effect of co-doping in enhancing the performance of nanostructured TiO2 based DSSC sensitized using extracts of Hibiscus Sabdariffa calyx

Abstract Calyx of Hibiscus Sabdariffa is found to possess ‘anthocyanin’ as major pigment and has been chosen as the natural dye for the present investigation. The calyx is found to contain both cyanidin and delphidin complexes usually in the form of glycosides and are bound to acyl functional groups. These functional groups contribute to the colour stability of the extract of Hibiscus Sabdariffa and are helpful in easy bonding with TiO2 molecules. In this study, undoped and doped TiO2 nanostructures have been synthesized by simple hydrothermal method. Structural studies reveal the presence of rutile phase and formation of secondary phase in case of doped samples. Morphological analysis revealed the formation of nanorods and nanoflowers depending on the dopant concentration. The photoelectric conversion efficiency of 6% sodium doped TiO2 based DSSC was 1.65 % and is 79 % higher than the undoped TiO2 based DSSC that exhibited an efficiency of 0.92 %. This efficiency value has been further found to improve by doping yeast and 6% sodium+6% yeast doped TiO2 based DSSC was found to exhibit an improved performance of 2.40 %. Even dye stability studies of doped TiO2 based DSSC revealed that the fabricated DSSCs are stable even after a period of 11 weeks.