Open AccessAn n-Si/n-Fe2O3 Heterojunction Tandem Photoanode for Solar Water Splitting
Author(s) -
Roel van de Krol,
Yongqi Liang
Publication year - 2013
Publication title -
chimia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.387
H-Index - 55
eISSN - 2673-2424
pISSN - 0009-4293
DOI - 10.2533/chimia.2013.168
Subject(s) - tandem , heterojunction , optoelectronics , materials science , water splitting , silicon , oxide , nanotechnology , chemistry , photocatalysis , composite material , catalysis , biochemistry , metallurgy
Few metal oxide photoanodes are able to reduce protons to hydrogen because their conduction band minimum is located at too positive potentials. This can be remedied by biasing the photoanode with a photovoltaic cell placed behind the photoanode. The disadvantage of such a tandem device is the rather complicated structure. Here, we demonstrate a very simple monolithic heterojunction tandem photoanode based on n-Si and n-type ?-Fe2O3. Detailed characterization of this system in a basic planar configuration reveals that the silicon generates a photovoltage of ?0.3 V, and that the heterojunction functions as a D4 tandem device in which the absorption of two photons leads to one high-energy electron in the external circuit. No Fermi level pinning occurs at the Si/Fe2O3 interface, and the tandem photoanode is thermodynamically able to split water without the need for an external bias potential. This suggests that the n-Si/n-Fe2O3 heterojunction photoanode is a promising system for solar water splitting.