Abstract:
In this study, a natural dye from the flowers of Mussaenda erythrophylla extracted separately
in ethanol and de-ionized water was employed as a photosensitizer in DSSCs. The quantitative
phytochemical analyses were performed on both extracts. The existence of flavonoids (anthocyanin)
and chlorophyll a pigments in the ethanol extract of the dye was confirmed by the UV–Visible
spectroscopy. The stability study performed on the said ethanol extract confirmed that the dye
extracted in ethanol was stable in the dark and did not degrade for nearly 50 days. The presence of
the dye molecules and uniform adsorption of them on the P25-TiO2 surface were confirmed by fourier
transform infrared spectroscopy and atomic force microscopy, respectively. Moreover, the influence
of dye concentration and pH on the optical properties of the dye was also studied. The natural dye
extracted in ethanol was employed in DSSCs, fabricated by utilizing the said dye sensitized P25-TiO2
photoanodes, I
−/I
−
3 electrolyte, and Pt counter electrode. Photovoltaic performances of the fabricated
devices were determined under simulated irradiation with the intensity of 100 mWcm–
2 using AM 1.5
filter. The device fabricated with the P25-TiO2 photoanode sensitized by the dye extracted in ethanol
at pH = 5 exhibited the best power conversion efficiency (PCE) of 0.41% with the JSC
of 0.98 mAcm–
2
which could be attributed to the optimum light absorption in the visible region of solar spectrum by
the chlorophyll a and anthocyanin molecules in the extracted natural dye.
