Optimization of current density of dye-sensitized solar cells by Cd substitution in the electron transport layer

This study addresses the growing need for energy worldwide and highlights the necessity of switching to sustainable options like dye-sensitized solar cells (DSSCs), which are well known for their affordability, ease of use, and competitive efficiency. Utilizing the sol–gel method, we synthesized diverse samples, including pristine TiO₂, Cd-doped TiO₂, and their heterostructures (TiO₂@Cd–TiO₂, Cd–TiO₂@TiO₂). A comprehensive evaluation encompassed structural, morphological, optical properties, and photovoltaic behavior through techniques like XRD, SEM, and UV–visible spectroscopy. Structural analysis highlighted the development of the anatase phase in all samples. The particles exhibited spherical grains, and heterostructures displayed dispersed particles with large sizes, enhancing electronic transport and dye absorption for efficient DSSCs. Cd–TiO₂@TiO₂ exhibits the shortest bandgap (3.24 eV). Notably, Cd–TiO₂@TiO₂ demonstrated favorable photovoltaic characteristics, including J_sc (8.65 ± 0.2 mA -cm²), V_oc (0.78 ± 0.2 V), FF (0.718 ± 0.1), and efficiency (4.848 ± 0.5). Electrochemical impedance spectroscopy (EIS) of TiO₂@Cd–TiO₂ and Cd–TiO₂@TiO₂ DSSCs unveiled distinct semicircles, indicating reduced charge transfer resistance and enhanced efficiency compared to TiO₂-only DSSCs. This research contributes vital insights for advancing sustainable and efficient solar cell technologies.