Organic Photoelectrochemical Cells Beyond Performance: Interface and Catalyst Engineering for Durability

ABSTRACT The transition toward carbon‐neutral energy systems has intensified interest in technologies that directly convert solar energy into chemical fuels and value‐added products. Among these, photoelectrochemical (PEC) systems integrate light absorption, photovoltage, and photocurrent generation, and electrochemical catalysis within a single device architecture. Beyond conventional inorganic semiconductors, organic photoelectrochemical cells (OPECs) based on π‐conjugated semiconductors are gaining attention by exploiting features difficult to achieve in inorganic counterparts. This review highlights recent advances in OPECs, focusing on water splitting systems for hydrogen and oxygen evolution. We first summarize fundamental operating principles, key device architectures, and performance metrics, followed by recent progress in p‐ and n‐type organic photoelectrodes. Interfacial engineering and catalyst integration strategies are discussed in terms of their compatibility with organic substrates and impact on charge‐transfer kinetics. Stability challenges under aqueous operation and emerging mitigation strategies are also examined. Finally, tandem configurations, bias‐free operation, and extensions beyond water splitting, including CO 2 reduction and selective organic transformations, are addressed. Key scientific and engineering challenges are identified to guide the transition of OPECs from laboratory demonstrations to scalable solar fuel technologies.