<p>This study focuses on analyzing the effect of lanthanum doping in Fe₂O₃ on the performance of photoelectrochemical (PEC) cells. Fe₂O₃ and lanthanum-doped Fe₂O₃ were synthesized using the hydrothermal method, where the La doping levels in Fe₂O₃ were 2.5%, 5.0%, and 7.5%. The structures, surface morphology, and elemental composition of Fe₂O₃ and La-doped Fe₂O₃ were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDS) techniques. UV–visible spectrum analysis revealed that the addition of La atoms had a slight influence on the energy bandgap. The PEC electrode performance was studied by chopped-light voltammetry (CLV). The CLV analysis revealed that Fe₂O₃ doped with 2.5% La had the highest photocurrent density of 0.225&#xa0;mA/cm², which is greater than three times that of the unimproved electrode. In this study, UV–visible absorption, photoluminescence spectroscopy (PL), and electrochemical impedance spectroscopy (EIS) were investigated to examine the physical relevance of the La improvement. As a result, it was found that the increase in charge carrier density is the most significant factor affecting the PEC performance. Therefore, doping Fe₂O₃ with 2.5% La increases charge carrier density and significantly improves PEC performance.</p>