Enhanced conversion efficiency enabled with natural dyes extracted from Mirabilis flower and Bixa seed revealing prospects of application of co-sensitized DSSC

In this report, we present the studies on co-sensitization effects of two natural dyes extracted from Mirabilis flower and Bixa seeds on TiO₂-based dye-sensitized solar cells (DSSC). The objective is to extend the spectral sensitivity and light-to-electrical energy conversion efficiency of the selected dyes. UV–visible absorption within the 480–580 nm and 400–500 nm range signify anthocyanin in Mirabilis flower and carotenoid in Bixa seed respectively. Bixa seed and Mirabilis flower extracted mixed natural dye exhibited absorption in 400–600 nm range. The study further established the co-sensitization through computational studies and electrochemical impedance spectroscopy (EIS) studies. With the use of Bixa seed and Mirabilis flower extracted dye, photovoltaic parameter short-circuit current density (J_sc) & conversion efficiency (η) were observed 0.20 mA/cm², 0.44 mA/cm² and 0.09 % 0.38 % respectively. The Bixa seed and Mirabilis flower extracts co-sensitized DSSC revealed enhanced J_sc 0.65 mA/cm² and η 0.40 %.