Preparation of a TiO₂-based dye-sensitized solar cell comprising anthocyanin from mangosteen pericarp (Garcinia mangostana, L.) as the sensitizer: Co-pigmentation effect on sensitizer and solar cell efficiency

A dye-sensitized solar cell (DSSC) is a device that converts solar energy into electric energy. In this study, TiO₂, nanotubes (TiO₂-NTs) sensitized with anthocyanin extracted from mangosteen pericarp (Garcinia mangostana L.) were used as part of a working electrode, whereas fluoride-doped tin oxide-platinum (FTO-Pt) was used as counter electrode. TiO₂-NTs were grown on a titanium plate via a two-step anodization method. Pt from an H₂PtCl₆ solution was deposited on an FTO surface prepared by spray pyrolysis. The anthocyanin extract was co-pigmented with benzoic acid to increase the stability of the DSSC and its visible light absorbance. The TiO₂ prepared by anodization was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and diffuse reflectance UV-Vis spectroscopy. Photocurrent evaluation using linear sweep voltammetry and multi pulse amperometry indicated that TiO₂-NTs were activated by UV light. Sensitization with anthocyanin-benzoic acid increased TiO₂-NT's response to visible light. The anthocyanin extract absorbed light in the visible region (400-600 nm), and as a result of its co-pigmentation with benzoic acid, absorbance increased. The efficiency of various DSSCs was evaluated, and data indicated that with sensitizers like anthocyanin alone or anthocyanin co-pigmented with benzoic acid at different ratios (1:0.5; 1:0.8; and 1:1 (v/w)) efficiency values were 0.2273 %, 0.2297 %, 0.2884 %, and 0.3709 %, respectively. The results indicate that the addition of benzoic acid to anthocyanin can improve DSSC performance.