An Organic Semiconductor Photoelectrochemical Tandem Cell for Solar Water Splitting

作者：Dan Zhang, Han-Hee Cho, Jun‐Ho Yum, M. Mensi, K. Sivula · 发表于：Advanced Energy Materials · 年份：2022 · DOI：10.1002/aenm.202202363 · 被引用次数：53

Photoelectrochemical 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 (VRHE) for solar water reduction with noticeable operational stability (retaining ≈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 cm2) 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 H2 and O2 production.