This study investigates the anisotropic carrier transport properties in Cu₂O thin films, focusing on the [111] orientation. The researchers developed a new method to grow single-crystal Cu₂O samples with three crystal orientations using ambient liquid-phase epitaxy. Broadband femtosecond transient reflection spectroscopy was used to quantify the anisotropic optoelectronic properties, revealing that carrier mobility along the [111] direction is significantly higher than in other orientations. Based on these findings, they fabricated polycrystalline Cu₂O photocathodes with an extremely pure (111) orientation and (111) terminating facets using a simple and low-cost method. These devices achieved a current density of 7 mA cm⁻² at 0.5 V versus the reversible hydrogen electrode under air mass 1.5 G illumination, representing a 75% improvement over state-of-the-art electrodeposited devices. The study also highlights the importance of bulk carrier recombination and surface effects in optimizing the performance and stability of Cu₂O photoelectrodes.This study investigates the anisotropic carrier transport properties in Cu₂O thin films, focusing on the [111] orientation. The researchers developed a new method to grow single-crystal Cu₂O samples with three crystal orientations using ambient liquid-phase epitaxy. Broadband femtosecond transient reflection spectroscopy was used to quantify the anisotropic optoelectronic properties, revealing that carrier mobility along the [111] direction is significantly higher than in other orientations. Based on these findings, they fabricated polycrystalline Cu₂O photocathodes with an extremely pure (111) orientation and (111) terminating facets using a simple and low-cost method. These devices achieved a current density of 7 mA cm⁻² at 0.5 V versus the reversible hydrogen electrode under air mass 1.5 G illumination, representing a 75% improvement over state-of-the-art electrodeposited devices. The study also highlights the importance of bulk carrier recombination and surface effects in optimizing the performance and stability of Cu₂O photoelectrodes.