A bright outlook on organic photoelectrochemical cells for water splitting

Abstract

Photoelectrochemcial (PEC) water splitting is increasingly attracting attention as a means to generate clean, renewable hydrogen fuel from solar energy. This Highlight article covers the key advances that have been made over recent years in organic photoelectrochemical (OPEC) cell research, and identifies a pathway forwards combining state-of-the-art materials and device engineering from both the organic photovoltaics and inorganic PEC water splitting communities. We discuss the advantages of using buried junction device architectures in OPEC photoelectrodes and identify the need for new materials for OPEC water splitting cells in order to improve their efficiency and operating stability. We present an overview on promising new absorbers and device architectures employed in the parallel field of organic photovoltaics with a critical view on requirements for OPEC water splitting. We also elaborate on progress made with organic multijunction cells that we see as promising photocathode designs for voltage-unassisted water splitting. Finally, we see the urgent need for benchmarking rules, in terms of performance and stability parameters, as this emerging field of OPEC water splitting progresses.