Chelating-Assisted Green Synthesis of TiO ₂ Nanoparticles from Mangosteen Pericarp for Defect Control and DSSC Performance

This work aims to examine the properties of titanium dioxide nanoparticles (TiO₂ NPs) synthesized through a sustainable, chelating-assisted green process using mangosteen (<i>Garcinia mangostana</i> L.) pericarp extracts for use as a semiconductor layer in dye-sensitized solar cells (DSSCs). X-ray diffraction (XRD) characterization revealed that the TiO₂ NPs have a tetragonal crystalline structure and are pure anatase. The optical characteristics examined using ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) showed a reduced bandgap energy, from 3.22 to 3.20 eV, with the use of mangosteen pericarp extract. The same trend is observed with the use of chelating agent concentration, decreasing from 3.20 to 3.10 eV at 30%, then increasing slightly to 3.14 eV at 50%. The TiO₂ NPs were further used as a semiconductor layer in a DSSC device sensitized with the commercial dye N719 and a natural dye derived from Malabar spinach (<i>Basella rubra</i> L.) fruit extract. The highest efficiency of 2.34% was achieved with a DSSC device fabricated from green-synthesized TiO₂ NPs using mangosteen pericarp extracted with 50% acetylacetone (AcAc) and sensitized with N719, slightly lower than that of commercial TiO₂ P25 (2.65%). The efficiencies of the same materials sensitized with natural dyes from Malabar spinach fruit extract are 0.69% and 1.01%, respectively. These results demonstrate the potential of using mangosteen pericarp waste and natural dyes for the sustainable, cost-effective fabrication of DSSCs.