Integrated Halide Perovskite Photoelectrodes for High-Efficiency and Durable Solar Water-Splitting

State-of-the-art photoelectrochemical cells (PECs) use single-crystalline III-V semiconductor-based tandem photovoltaics to drive bias-free water-splitting to generate green hydrogen. However, practical implementation of PECs based on these photo-absorbers has been shown to be cost prohibitive. We report the design and development of a conductive barrier (CAB) which translates >99% of the photoelectric power to chemical. We demonstrate the efficacy of the barrier using two bias free device designs. First involved a series photocathode-photoanode device which resulted in a solar-to-hydrogen efficiency (STH) of13.1% and 18 hours of continuous operation, limited by the n-i-p perovskite- stability. Second involved a silicon-perovskite tandem photoanode, which enabled a record 20.9% STH efficiency with >100 hours of operation under AM1.5 illumination.. We anticipate that these advances will enable the development of a solar-driven water-splitting technology to produce green H2 using low-cost absorbers and corrosion barriers.