Sekar, ArvindhMoreno-Naranjo, Juan ManuelLiu, YongpengYum, Jun-HoDarwich, Barbara PrimeraHan-Hee ChoGuijarro, NestorYao, LiangSivula, Kevin2022-03-142022-03-142022-03-142022-02-0710.1021/acsami.1c21440https://infoscience.epfl.ch/handle/20.500.14299/186250WOS:000758053600001The use of a bulk heterojunction of organic semiconductors to drive photoelectrochemical water splitting is an emerging trend; however, the optimum energy levels of the donor and acceptor have not been established for photoanode operation with respect to electrolyte pH. Herein, we prepare a set of donor polymers and non-fullerene acceptors with varying energy levels to probe the effect of photogenerated electron injection into a SnO(2)(-)based substrate under sacrificial photo-oxidation conditions. Photocurrent density (for sacrificial oxidation) up to 4.1 mA cm(-2) was observed at 1.23 V vs reversible hydrogen electrode in optimized photoanodes. Moreover, we establish that a lower lying donor polymer leads to improved performance due to both improved exciton separation and better charge collection. Similarly, lower-lying acceptors also give photoanodes with higher photocurrent density but with a later photocurrent onset potential and a narrower range of pH for good operation due to the Nernstian behavior of the SnO2, which leads to a smaller driving force for electron injection at high pH.Nanoscience & NanotechnologyMaterials Science, MultidisciplinaryScience & Technology - Other TopicsMaterials Sciencephotoelectrochemistrythiophenedicarboximidebenzodithiophenepolymerrylene diimidenon-fullerene acceptorspolymer solar-cellswater oxidationside-chainsperformancetext::journal::journal article::research article