Designing Perovskite/Silicon Tandem‐Based Single Photoelectrode Modules for Practical Solar Hydrogen Production

Abstract Thanks to decades of persistent research, photoelectrochemical (PEC) water splitting has surpassed the early commercialization benchmark by achieving solar‐to‐hydrogen (STH) conversion efficiencies over 10%. However, commercial viability of PEC technology now demands the STH efficiencies exceeding 20%, alongside long‐term operational stability and scalability to practical panel sizes. While multi light‐absorber PEC systems can achieve the required photovoltage and photocurrent, their structural complexity and elevated fabrication costs remain barriers to widespread adoption. This perspective article evaluates the potential of single photoelectrode (S4)‐based PEC systems as a simplified, cost‐effective alternative to traditional double photoelectrode (D4) designs. These systems benefit from recent breakthroughs in efficient, low‐cost multi‐junction solar cells, particularly all‐perovskite and perovskite(PSK)/silicon(Si) tandems. It is briefly reviewed the latest advances in S4‐based PEC water splitting and presents a conceptual design for a PSK/Si tandem photoelectrode modules capable of achieving high STH efficiency, durability, and scalability. A strategy is also proposed for scaling from lab‐scale devices to commercial‐sized modules and panels, with an emphasis on maintaining high STH performance. This perspective article outlines a promising path toward sustainable and economically viable solar hydrogen production to contribute to sustainable energy transition of the world.