Operando insights into stability of perovskite-based solar water splitting devices

Perovskite-based solar water splitting systems are promising candidates for addressing environmental challenges, exceeding the commercialization efficiency of solar-to-hydrogen (STH) at >10%. However, the operational stability remains suboptimal due to insufficient in situ/operando insights into charge carrier dynamics. Here, we investigate the role of charge accumulation on operational stability through operando catalytic modulation via near-infrared (NIR) toggling on a photothermal catalyst. Electrochemical analyses under operando NIR toggling demonstrate enhanced hydrogen evolution reaction kinetics and reduced charge recombination. In situ analyses confirm that reduced charge accumulation suppresses ion migration in the perovskite layer, thereby enhancing operational stability. The NIR-irradiated cathode delivers a photocurrent density of 25.48 mA cm–2, maintaining 90% of its initial photocurrent density at 0 VRHE for 310 h. A parallelly-illuminated coplanar system with NIR-irradiated perovskite-based water splitting cathode operates without bias, achieving a STH efficiency of 15.18%, retaining 70% of their initial performance for 115 h. The origin of device failure in fully encapsulated perovskite-based solar water splitting devices remains poorly understood. Here, the authors report an operando catalytic activity modulation strategy utilizing a photothermal catalyst with NIR laser toggling to monitor charge accumulation dynamics.