Characterization of natural dyes on ZnO and TiO 2 thin films for applications in DSSC

In this work, we present a comparative study of two types of dye-sensitized solar cells (DSSCs) fabricated using natural dyes extracted from Achiote seeds, Brazil and Taray bark. The dyes were impregnated in ZnO and TiO 2 thin films. ZnO, TiO2, ZnO/dyes and TiO2/dyes structures were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), ultraviolet–visible spectroscopy (UV–Vis), infrared spectroscopy (IR spectroscopy) and current–voltage (I–V) techniques. IR analysis shows that the films impregnated with the dyes show anchoring to them and bands characteristic of COOH and OH functional groups. The results of UV–Vis spectroscopy show that the strongest absorption in the visible region is provided by dyes of the Achiote seeds, bark of Brazil and bark of Taray. The performance of the DSSCs device was evaluated to determine the influence of ZnO/dyes and TiO 2 /dyes photoanodes with platinum photocathodes. The manufactured DSSCs showed a conversion efficiency for TiO 2 of η = 3.65, 3.63 and 3.98% and for ZnO-based DSSCs of η = 3.09, 2.81 and 2.54% for Achiote seed, Brazilian bark and Taray bark, respectively.