Supplementary information:
Fig. S1 Solar light assisted photodegradation spectrum of (a) Malabar nightshade, (b) Cactus, (c) MB and
(d) Eosin dyes in the wavelength range of 300 nm to 800 nm
The absorption spectra in the wavelength range of 300 nm to 800 nm (UV-Visible domain) are shown
in Fig.S1. The absorption spectrum of Eosin and MB shows characteristic absorption peaks in the wavelength
range of 450-550 nm and 535-700 nm, respectively. The absorption spectrum of Cactus and Malabar nightshade
shows a wide absorption peak with absorption maximum at 536 nm for corresponds to betacyanin pigment [A].
No additional absorption peak is detected at lower wavelengths for dyes extracted from Cactus and Malabar
nightshade. It indicates that the betacyanin concentration is found to be high in these natural extracts. The
decreased absorption intensity with increase in irradiation time represents that the color of these natural dyes
gets bleached gradually. In addition, the occurred peak shift (hyperchromic effect) in Cactus and Malabar
nightshade may due to the protonation of betalain pigments in polar solvent (water) with increasing the time
prolongation [B].
Fig. S2 J-V characteristics of ZnO based DSSCs sensitized with N719 dye
The J-V curve of hexagonal ZnO based DSSC sensitized with N719 dye is shown in Fig. S2. It shows improved
PCE of ~ 1.53% than other natural and organic dye based devices due to increased FF (71.78%) by reduced
recombination dynamics, because of the presence of metal ions in ruthenium complex.
References
[A] G. Calogero, G. Di Marco, S. Cazzanti, S. Caramori, R. Argazzi, A. Di Carlo, C.A. Bignozzi, Efficient DyeSensitized Solar Cells Using Red Turnip and Purple Wild Sicilian Prickly Pear Fruits, International Journal of
Molecular Sciences 11(1) (2010) 254.
[B] S.K. Reshmi, K.M. Aravindhan, P. Suganyadevi, The effect of light, temperature, pH on stability of
betacyanin pigments in basella alba fruit, Asian J. Pharm. Clin. Res 4(3) (2012) 107-110.