Simple Hydrothermal Method for One-Dimensional Synthesis of Al-Doped ZnO for an Organic Dye-Based DSSC Application

Zinc oxide (ZnO) nanorods are promising photoanode materials for dye-sensitized solar cells (DSSCs) due to their high electron mobility, favorable aspect ratio, and tunable optoelectronic properties. In this study, vertically aligned ZnO nanorods were hydrothermally grown on fluorine-doped tin oxide (FTO) substrates and doped with Al³⁺ (1–7 at%) to optimize charge transport. X-ray diffraction (XRD) analysis confirmed successful Al³⁺ incorporation, evidenced by a slight peak shift, while retaining the hexagonal wurtzite structure. The nanorods exhibited controlled morphologies, with diameters ranging from 78 to 141 nm and aspect ratios varying between 13% and 37%. Optical characterization revealed that sensitization with D205 dye extended light absorption into the visible spectrum, significantly improving photon harvesting. Among the tested dopant concentrations, the 1% Al³⁺-doped ZnO (AZO-1%) photoanode demonstrated optimal performance, achieving a short-circuit current density (JSC) of 25.7 mA/cm² and a power conversion efficiency (PCE) of 4.15%. These results highlight the synergistic effects of Al³⁺ doping and nanostructural engineering in enhancing DSSC performance through improved charge collection and reduced recombination.