All-organic semiconductor tandem devices for scalable photoelectrochemical solar H2 production

초록

Photoelectrochemical (PEC) water splitting offers a direct route to solar hydrogen, but organic semiconductor-based photocathodes have been limited by insufficient photovoltage and interfacial instability. Here, we demonstrate monolithic all-organic semiconductor tandem photocathodes that address these coupled photovoltage and interfacial-stability constraints. A MoOx/2PACz hybrid interconnecting layer (ICL) replaces conventional PEDOT:PSS-based interconnects, suppressing interfacial recombination and enabling stable sequential deposition of front and back subcells. The resulting tandem photocathodes reach an onset potential of 1.67 V vs. RHE and a 7.9% solar-to-hydrogen (STH) efficiency under unbiased two-electrode operation, which, to our knowledge, is the highest reported for organic semiconductor-based photocathodes operating without external bias, while retaining 86% of their photocurrent over 10 h under three-electrode operation. Coupled with an earth-abundant NiFeCo OER catalyst and an ultralow-Pt CoSMoS-Pt HER catalyst, the system operates in a single alkaline electrolyte without an ion-exchange membrane. Large-area modules up to 320 cm2 demonstrate outdoor bias-free hydrogen production. Techno-economic analysis yields a levelized hydrogen cost of 9.26 $kg-1undercurrentconditions,withsensitivityanalysisprojecting4.26$ kg−1 under optimized STH efficiency and production scale. © 2026 Elsevier B.V.

키워드