Earth-abundant iron oxysulfide (FeSxOy) for bandgap optimization

X. Han, B. Zhou, Meng Tao

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations


Transition metal sulfides with small bandgap are attractive for solar cell applications since most transition metals are abundant and many can be deposited in solution. Pyrite FeS2, with a bandgap of 0.95 eV, is one of the most desirable for solar cell applications. The problem with FeS2 is that its bandgap is ∼0.45 eV smaller than the optimum bandgap for maximum efficiency, which should be ∼1.4 eV. In this paper, we propose the concept of metal oxysulfide as the approach to a low-cost Earth-abundant semiconductor with a direct bandgap of ∼1.4 eV for terawatt-scale solar cells. This is because the bandgap of Fe2O3 is 2.2 eV. By introducing O into FeS2, the bandgap should increase. In our experiments, we use oxidation of electrodeposited FeSx for this purpose. FeSx films were electrodeposited on FTO-coated glass. Post-deposition annealing was carried out in vacuum to make FeSx films denser and more stable in air. SEM and EDX confirm that the as-grown FeSx film is amorphous and the S/Fe ratio in the film is slightly above 1. Oxidation of the FeS x films was performed either in a tube furnace under air or electrochemically in an electrolyte. After oxidation, the bandgap in the resultant FeSxOy is ∼1.3 eV by electrochemical oxidation and ∼1.1 eV by thermal oxidation. Further optimization is expected to produce a FeSxOy with a ∼1.4 eV bandgap.

Original languageEnglish (US)
Title of host publicationProgram - 38th IEEE Photovoltaic Specialists Conference, PVSC 2012
Number of pages5
StatePublished - Nov 26 2012
Event38th IEEE Photovoltaic Specialists Conference, PVSC 2012 - Austin, TX, United States
Duration: Jun 3 2012Jun 8 2012

Publication series

NameConference Record of the IEEE Photovoltaic Specialists Conference
ISSN (Print)0160-8371


Other38th IEEE Photovoltaic Specialists Conference, PVSC 2012
Country/TerritoryUnited States
CityAustin, TX


  • bandgap
  • iron sulfide
  • light absorber
  • oxysulfide

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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