Silicon-based photoelectrodes for solar fuel production have attracted great interest over the past decade, with the major challenge being silicon’s vulnerability to corrosion. A metal–insulator–semiconductor architecture, in which an insulator film serves as a protection layer, can prevent corrosion but must also allow low-resistance carrier transport, generally leading to a trade-off between stability and efficiency. In this work, we propose and demonstrate a general method to decouple the two roles of the insulator by employing localized dielectric breakdown. This approach allows the insulator to be thick, which enhances stability, while enabling low-resistance carrier transport as required for efficiency. This method can be applied to various oxides, such as SiO₂ and Al₃O₂. In addition, it is suitable for silicon, III–V compounds, and other optical absorbers for both photocathodes and photoanodes. Finally, the thick metal-oxide layer can serve as a thin-film antireflection coating, which increases light absorption efficiency.

Nature Materials (2016) doi:10.1038/nmat4801
Received 30 September 2015 Accepted 01 August 2016 Published online 07 November 2016

http://www.nature.com/nmat/journal/vaop/ncurrent/full/nmat4801.html