Band alignment and electrocatalytic activity at the <italic>p</italic>-<italic>n</italic> La0.88Sr0.12FeO3/SrTiO3(001) heterojunction.

Ferrite perovskites have exhibited promising <italic>p</italic>-type conductivity and oxygen evolution reaction (OER) activity. In this work, we investigate heteroepitaxial <italic>p-n</italic> junctions formed by La0.88Sr0.12FeO3 and <italic>n</italic>-SrTiO3(001). Sr substitution for La in LaFeO3 is shown to be effective for introducing p-type conductivity, lowering the optical bandgap, and enhancing electrocatalytic OER. A staggered, type-II band alignment with a large built-in potential within the LSFO forms due to the polar interface. This electronic structure facilitates charge transfer across the <italic>p-n</italic> junction and accounts for the strongly thickness-dependent extent of OER we observe. [ABSTRACT FROM AUTHOR]