Photoelectrochemical (PEC) water splitting devices replace electrical contacts in a solid-state solar cell with a solid/liquid junction to improve the solar-to-H2conversion efficiency and reduce system cost. The wireless configuration can fully use the advantage of the PEC by removing all electrical contacts; however, the wired configuration with the electrical contact on its back side has been widely studied to facilitate device characterization. In this study, a wireless PEC water splitting device made of a commercially available III-V triple-junction solar cell protected by transparent TiO2 is demonstrated with high efficiency and stability. The wireless device produces both H2 and O2 products in a stoichiometric ratio in 13% of solar-to-H2 conversion efficiency over ∼12 h, and the total amount of H2 product during the lifetime of the device reaches 51 mL/cm2 , which is the highest value reported from wireless PEC devices to the best of our knowledge.
Bibliographical noteFunding Information:
The Center for Surface Physics and Catalysis is funded by the Villum Foundation V-SUSTAIN grant no. 9455 . We thank Micha Ben-Naim and Reuben J. Britto for sharing technical discussions on H2 lifetime.