RESUMO
The use of new natural dyes derived from Leucophyllum frutescens and Ehretia microphylla as well as their combination in dye-sensitized solar cells (DSSCs) has been explored for the first time in the current work. The primary pigments that sensitize the semiconductor TiO2 films were found to be carotenoid, anthocyanin, and chlorophyll. Pigments from Leucophyllum frutescens and Ehretia microphylla were designated as LF and EM, and their mixture blended at volume percent of 50:50, 75:25, and 25:75 were labeled as LE1, LE2, and LE3, respectively. The absorption range, emission intensities, and the functional groups of the dyes and dye-loaded TiO2 photo-anode films were analyzed using ultraviolet-visible, photoluminescence and Fourier transform infrared spectroscopy. The surface morphology of bare and sensitized TiO2 films was identified through scanning electron microscopy (SEM). To evaluate the photovoltaic performance of the fabricated devices, the current-voltage characteristics, electrochemical impedance spectroscopy analysis and incident photon-to-current conversion efficiency measurements were performed. The study found that the co-sensitized cell LE2 outperformed both single and mixed dye-based cells, achieving a maximum conversion efficiency of 1.33% with a Voc of 516 mV and a Jsc of 2.55 mA cm-2. This synergetic effect of natural dyes proved the superior performance of DSSCs with co-sensitization.
