DYE-SENSITIZED SOLAR CELLS WITH EXTRACTS OF BLACK BEANS (PHASEOLUS VULGARIS) AND CURCUMIN (CURCUMA LONGA L.)

Abstract

This work sought to assess the viability of the use of an extract of black bean (Phaseolus vulgaris) in dye- sensitized solar cells (DSSC), comparing it with extracts of turmeric (Curcuma longa L.). Each DSSC was built with two plates of conductive glass. One plate was covered with TiO2, sinterized from a colloidal suspension, forming the anode; the other plate was covered with graphite, forming the cathode. Five extracts were prepared: an aqueous extract of black beans, three extracts of turmeric, with extraction time of 1 h, in methanol, ethanol and acetone, and an extract of turmeric in acetone, with extraction time of 24h. The essays with the extracts of turmeric were performed in a DSSC, bleaching the anode with a solution of sodium hypochlorite between them. Essays without dyes and with the extract of black bean were performed in another DSSC. A circuit was built to preliminarly assess the electrical performance of the cells. The highest power output was obtained with the methanolic extract of turmeric (62 μW). With the extract of black beans, the power output reached around 21 μW. The bleaching technique may have degraded the TiO2 layer. The results seem to indicate that the extracts of black beans and turmeric may be used to build this kind of photovoltaic cell.