Zhang, DanCho, Han-HeeYum, Jun-HoMensi, MounirSivula, Kevin2022-09-262022-09-262022-09-262022-09-0810.1002/aenm.202202363https://infoscience.epfl.ch/handle/20.500.14299/190986WOS:000851234900001Photoelectrochemical cells employing organic semiconductors (OS) are promising for solar-to-fuel conversion via water splitting. However, despite encouraging advances with the half reactions, complete overall water splitting remains a challenge. Herein, a robust organic photocathode operating in near-neutral pH electrolyte by careful selections of a semiconducting polymer bulk heterojunction (BHJ) blend and organic charge-selective layer is realized. The optimized photocathode produces a photocurrent density of >4 mA cm(-2) at 0 V vs the reversible hydrogen electrode (V-RHE) for solar water reduction with noticeable operational stability (retaining approximate to 90% of the initial performance over 6 h) at pH 9. Combining the optimized BHJ photocathode with a benchmark BHJ photoanode leads to the demonstration of a large-area (2.4 cm(2)) organic photoelectrochemical tandem cell for complete solar water splitting, with a predicted solar-to-hydrogen (STH) conversion efficiency of 0.8%. Under unassisted two-electrode operation (1 Sun illumination) a stabilized photocurrent of 0.6 mA and an STH of 0.3% are observed together with near unity Faradaic efficiency of H-2 and O-2 production.Chemistry, PhysicalEnergy & FuelsMaterials Science, MultidisciplinaryPhysics, AppliedPhysics, Condensed MatterChemistryEnergy & FuelsMaterials SciencePhysicsorganic semiconductorsphotoanodesphotocathodessolar water splittinghydrogen-productionphosphonic-acidsanchoring groupsoxideoxidationtio2text::journal::journal article::research article