Síntese, caracterização e aplicação dos óxidos de CeO2, TiO2, ZrO2 e SnO2 em células solares sensibilizadas por corante (CSSC)

Abstract

Dye-sensitized solar cells (DSSCs), which belong to the third generation of photovoltaic technologies, have attracted considerable attention due to their low production cost compared with conventional photovoltaic technologies. These devices consist of a photoanode, a counter electrode, and an electrolyte, with titanium dioxide (TiO₂) being the most widely used semiconductor material. The present study aimed to synthesize, characterize, and evaluate CeO₂, SnO₂, and ZrO₂ semiconductor oxides as alternative photoanode materials to TiO₂ in DSSCs. The semiconductor oxides were synthesized using the Pechini method and characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, open-circuit potential measurements, and electrochemical impedance spectroscopy (EIS). The DSSCs were assembled in a sandwich configuration using a graphene counter electrode, an active area of 0.2 cm², and an electrolyte containing the I₃⁻/I⁻ redox couple. The synthesized oxides exhibited high crystallinity, although with irregular morphology. The estimated band gap energies were 2.8 eV, 3.0 eV, 3.1 eV, and 4.8 eV for CeO₂, TiO₂, SnO₂, and ZrO₂, respectively. All fabricated DSSCs exhibited photosensitivity, generating electrical potential under light irradiation. Among the evaluated materials, the TiO₂-based cell exhibited the lowest charge-transfer resistance (Rct = 57.8 kΩ), indicating superior electrochemical performance compared with the other investigated oxides. These results demonstrate the potential of the synthesized semiconductor oxides for photovoltaic applications and contribute to the development of alternative photoanode materials for dye-sensitized solar cells.