Carrier Regulation and Interface Catalysis Synergy Enhance the Water Splitting Efficiency of Perovskite Photoelectrodes

Perovskite-based photoelectrodes have a high light absorption coefficient, long carrier diffusion length, and adjustable band gap, making them a hotspot in the field of green hydrogen production. By optimizing the behavior of photogenerated carriers and the kinetics of interfacial reactions, we form a complementary mechanism, which can significantly enhance the overall performance. Using rubidium fluoride (RbF) to enhance electron mobility and carrier lifetime and octylammonium iodide (OAI) to suppress carrier recombination at the hole transport layer (HTL)/perovskite (PVK) interface and on the hydrophobic perovskite surface can improve the intrinsic recombination losses. The average photogenerated carrier lifetime has been increased from 126 to 238 ns. Moreover, the effective passivation of defects in target perovskite solar cells (PSCs) leads to a reduction in defect density. Depositing a NiFe catalyst to promote the transfer of charges to the electrolyte can improve the interface's reaction losses. During the oxygen evolution reaction, the overpotential is 220 mV at a current density of 10 mA cm^-2. Subsequent encapsulation and integration of the catalyst with the PSCs enable dual strategies for carrier management and interfacial catalysis, synergistically enhancing the water-splitting performance. Finally, a system with parallel illumination of perovskite photoanodes and photocathodes achieves an unassisted solar-to-hydrogen (STH) efficiency of 13.7%. This work provides an important strategy for controlling the photogenerated carrier loss in photoelectrodes that can effectively enhance the STH efficiency of the photoelectrodes.