Layer-by-layer assembled perovskite/polymer photoelectrochemical devices with enhanced performance and stability

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Organic–inorganic hybrid perovskites (OIHPs) offer a promising pathway for the development of low-cost and efficient solar hydrogen production systems. Despite remarkable advancements, poor chemical stability of the OIHPs in aqueous environments limits their practical applications. Herein, we design a photoelectrochemical (PEC) device consisting of layer-by-layer assembled P(VDF-TrFE)/CH₃NH₃PbBr₃ (MAPbBr₃) hybrid films that simultaneously achieve efficient and stable solar water splitting. The multilayered PEC device shows long-term chemical stability for ∼7200 s in an aqueous electrolyte due to hydrophobic P(VDF-TrFE) encapsulation. In addition, leveraging the ferroelectric coupling effect, we achieved an extraordinary photocurrent tunability, from 30 μA/cm^-2 to 1.09 mA/cm^-2 (∼3500% modulation at 0.4 V vs Ag/AgCl), simply by switching the polarization direction in the ferroelectric layers. Comprehensive characterizations reveal that such PEC performance tuning originates from ion migration induced changes in the band alignment, which regulates the charge transfer efficiency at the photoelectrode/electrolyte interface. Our work demonstrates that coordinating functional semiconductors with ferroelectric polymers in a hybrid multilayer framework presents a versatile strategy for engineering high-performance composites and advances the design of next-generation solar hydrogen production systems.