Photovoltaic performance of semi-pure and crude dye extracts from the leaf of Lonchocarpus cyanescens as natural sensitizer for dye-sensitized solar cell (DSSC)

In this study, the natural dye was extracted from Lonchocarpus cyanescens (LC), and both the crude and semi-pure extracts were used as sensitizers for dye-sensitized solar cells (DSSCs). Characterization of the prepared dye was carried out using UV-vis absorption spectroscopy. Different DSSCs based on the extracted dye were fabricated. The light conversion efficiency of the DSSC from the purified extract was found to be 0.057%. This value is lower than the performance of the DSSC from the crude extract of Lonchocarpus cyanescens with 0.116% efficiency. An electrochemical study of the cells was carried out to validate the results using cyclic voltammetry and electrochemical impedance spectroscopy (EIS) for the first time. The difference in the performances of the 2 samples is attributed to the loss of co-absorbers that acted in synergy with absorbing species of crude extract during the process of purification. These absorbing species also act as adsorbing species to the TiO2 surface. In this study, we have established the relationship between the photovoltaic performance of semi-pure and crude extracts of Lonchocarpus cyanescens DSSCs and their charge transport properties.