Natural extracts from Rhus microphylla and Opuntia joconostle as mono and co-sensitizers for efficiency enhancement of nano-TiO2 based dye-sensitized solar cells

Abstract

In this work, six plants are presented to obtain different molecules with distinct properties to be used in dye-sensitized solar cells (DSSC). Cells have been assembled using Opuntia joconostle (xoconostle), Rhus microphylla (limilla), Tagetes erecta (marigold flower), Euphorbia pulcherrima (poinsettia flower), Bougainvillea spectabilis (bougainvillea) and Camellia sinensis (green tea) as individual and mixed pigments. In the case of xoconostle and limilla this is the first time that their extracts have been used as sensitizers in DSSC. Having these natural dyes, the co-sensitization technique was adopted to improve the photovoltaic performance of the solar cells. The best performance with the individual extracts was from the poinsettia flower having a conversion efficiency of 0.0022 % with Voc of 0.29 V, Jsc of 0.014 mA/cm2 and FF of 48.56, in the case of co-pigmentation, the best mixture was poinsettia flower with xoconostle and green tea (NXT) having a conversion efficiency of 0.0044 % with Voc of 0.34 V, Jsc of 0.035 mA/cm2 and FF of 44.50, using irradiation of 1000 W/m2 at 25°C. The purpose of mixed dyes is to absorb a wider interval of the electromagnetic spectra. Computational calculations based on the Density Functional Theory were used to calculate each molecule’s HOMO and LUMO levels.