Illumination-Dependent Charge Carrier Dynamics and Photoelectrochemical Performance of LaFeO3

Lanthanum iron oxide (LaFeO3) exhibits strong ultraviolet (UV) absorption, making its photoelectrochemical (PEC) performance highly dependent on the spectral overlap between illumination and its absorption profile. In this work, the PEC behavior of LaFeO3 thin films was investigated under two illumination sources: a xenon arc lamp with broadband emission, including UV photons, and a light-emitting diode (LED) lamp with negligible UV contribution. The structural and optoelectronic properties of the films were tuned by varying the number of spin-coated layers, and charge carrier dynamics were analyzed to quantify recombination rates and carrier lifetimes. PEC measurements were further optimized using O₂-saturated electrolytes, considering the catalytic role of LaFeO3 in oxygen reduction. Under xenon arc lamp illumination with O2 purging, the photocurrent density initially reached ~0.58 mA cm⁻2 and stabilized at ~0.39 mA cm⁻2 after 3 h, significantly outperforming other illumination and environmental conditions. These results highlight the critical role of illumination spectra and electrolyte environment in modulating charge separation and transport, offering guidelines for enhancing the practical PEC performance of LaFeO3-based photoelectrodes.