Influences of dye pH on the efficiency of dye-sensitized solar cells using natural dye extracted from Clitoria ternatea

ANGELICA SHALENE T ESTERA, JOEY F MARTINEZ, DOREEN MARIE S SORONGON, and ARIS LARRODER, Ph. D.
Philippine Science High School – Western Visayas Campus, Brgy. Bito-on, Jaro, Iloilo City 5000, Department of Science and Technology – Science Education Institute, Philippines

Abstract
The efficiency of dye-sensitized solar cell (DSSC) is dependent on the nature, optimization and compatibility of its components. A strong adsorption of the dye unto the titanium dioxide (TiO₂) is essential for the efficient electron injection into the TiO² semiconductor. Clitoria ternatea (CT) has a relatively high thermal stability, absorbance level, and anthocyanin content; however, it contains longer aromatic groups which affect the binding of dye molecules into the TiO₂ surface resulting to relatively low efficiency. This study was conducted to determine the influences of CT dye at different pH level, specifically, pH 1.0, 4.0, and 5.8 as dye sensitizer on the efficiency of DSSCs. Results show that CT extracts at pH 5.8 (control) has the highest absorbance followed by pH 4.0, and pH 1.0. However, when the dyes were sensitized in the TiO₂, pH 4.0 has the highest amount of dye adsorbed and energy conversion efficiency of 0.05%.

Keywords: DSSC, Clitoria ternatea, photovoltaic, adsorption, pH