Suppression of Undesired Losses in Organometal Halide Perovskite‐Based Photoanodes for Efficient Photoelectrochemical Water Splitting

Organometal halide perovskites (OHPs) have become potential candidates for high‐efficiency photoelectrodes for use in photoelectrochemical (PEC) water splitting. However, undesired losses, such as the non‐radiative recombination of photogenerated carriers and sluggish reaction kinetics of PEC water splitting, are the main limitations to achieving maximum efficiency for OHP‐based photoelectrodes. Herein, high‐efficiency OHP‐based photoanodes with a rational design that suppresses the undesired losses is reported. As a rational design for OHP‐based photoanodes, the defect‐passivated electron transport layers effectively suppress the undesired recombination of photogenerated carriers from the OHP layers. In addition, Fe‐doped Ni 3 S 2 with a high catalytic activity promotes the reaction kinetics of PEC water oxidation, thereby suppressing the undesired losses at the interface between the OHP photoanodes and electrolytes. The fabricated Fe‐doped Ni 3 S 2 /Ni foil/OHP photoanodes exhibit a remarkable applied bias photon‐to‐current efficiency of 12.79%, which is the highest of the previously reported OHP‐based photoanodes by suppressing undesired losses. The strategies for achieving high‐efficiency OHP‐based photoanodes provide insights into the rational design of photoelectrodes based on OHPs.