Realizing solar-to-hydrogen (STH) efficiencies close to 20% using low-cost semiconductors remains a major step toward accomplishing the practical viability of photoelectrochemical (PEC) hydrogen generation technologies. Dual-absorber tandem cells combining inexpensive semiconductors are a promising strategy to achieve high STH efficiencies at a reasonable cost. Here, a perovskite photovoltaic biased silicon (Si) photoelectrode is demonstrated for highly efficient stand-alone solar water splitting. A p+nn+ -Si/Ti/Pt photocathode is shown to present a remarkable photon-to-current efficiency of 14.1% under biased condition and stability over three days under continuous illumination. Upon pairing with a semitransparent mixed perovskite solar cell of an appropriate bandgap with state-of-the-art performance, an unprecedented 17.6% STH efficiency is achieved for self-driven solar water splitting. Modeling and analysis of the dual-absorber PEC system reveal that further work into replacing the noble-metal catalyst materials with earth-abundant elements and improvement of perovskite fill factor will pave the way for the realization of a low-cost high-efficiency PEC system.
KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: S.K.K. and H.S. contributed equally to this work. The ﬁnancial support from the Australian government through the Australian Research Council (ARC) and Australian Renewable Energy Agency (ARENA) is gratefully acknowledged. Access to the facilities of the Australian National Fabrication Facility (ANFF) is also gratefully acknowledged.