Improving the Back Surface Field on an Amorphous Silicon Carbide Thin Film Photocathode for Solar Water Splitting

Paula Perez-Rodriguez, Drialys Cardenas-Morcoso, Ibadillah A. Digdaya, Andrea Mangel Raventos, Paul Procel, Olindo Isabella, Sixto Gimenez, Miro Zeman, Wilson A. Smith, Arno H.M. Smets

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)
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Abstract

Amorphous silicon carbide (a-SiC:H) is a promising material for photoelectrochemical water splitting owing to its relatively small band-gap energy and high chemical and optoelectrical stability. This work studies the interplay between charge-carrier separation and collection, and their injection into the electrolyte, when modifying the semiconductor/electrolyte interface. By introducing an n-doped nanocrystaline silicon oxide layer into a p-doped/intrinsic a-SiC:H photocathode, the photovoltage and photocurrent of the device can be significantly improved, reaching values higher than 0.8V. This results from enhancing the internal electric field of the photocathode, reducing the Shockley-Read-Hall recombination at the crucial interfaces because of better charge-carrier separation. In addition, the charge-carrier injection into the electrolyte is enhanced by introducing a TiO2 protective layer owing to better band alignment at the interface. Finally, the photocurrent was further enhanced by tuning the absorber layer thickness, arriving at a thickness of 150nm, after which the current saturates to 10mAcm-2 at 0V vs. the reversible hydrogen electrode in a 0.2m aqueous potassium hydrogen phthalate (KPH) electrolyte at pH4.

Original languageEnglish
Pages (from-to)1797-1804
Number of pages8
JournalChemSusChem
Volume11
Issue number11
DOIs
Publication statusPublished - 2018

Keywords

  • Charge carrier injection
  • Hydrogen
  • Silicon carbide
  • Titanium dioxide
  • Water splitting

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