Core Levels, Band Alignments, and Valence-Band States in CuSbS2 for Solar Cell Applications

Andriy Zakutayev, Adam Welch, Francisco Willian De Souza Lucas, Thomas Whittles, Tim Veal, Christopher Savory, James Gibbon, Max Birkett, Richard Potter, David Scanlon, Vinod Dhanak

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73 Scopus Citations


The earth-abundant material CuSbS2 (CAS) has shown good optical properties as a photovoltaic solar absorber material, but has seen relatively poor solar cell performance. To investigate the reason for this anomaly, the core levels of the constituent elements, surface contaminants, ionization potential, and valence-band spectra are studied by X-ray photoemission spectroscopy. The ionization potential and electron affinity for this material (4.98 and 3.43 eV) are lower than those for other common absorbers, including CuInxGa(1-x)Se2 (CIGS). Experimentally corroborated density functional theory (DFT) calculations show that the valence band maximum is raised by the lone pair electrons from the antimony cations contributing additional states when compared with indium or gallium cations in CIGS. The resulting conduction band misalignment with CdS is a reason for the poor performance of cells incorporating a CAS/CdS heterojunction, supporting the idea that using a cell design analogous to CIGS is unhelpful. These findings underline the critical importance of considering the electronic structure when selecting cell architectures that optimize open-circuit voltages and cell efficiencies.

Original languageAmerican English
Pages (from-to)41916-41926
Number of pages11
JournalACS Applied Materials and Interfaces
Issue number48
StatePublished - 6 Dec 2017

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.

NREL Publication Number

  • NREL/JA-5K00-70595


  • band alignments
  • copper antimony sulfide
  • CuSbS
  • density of states
  • DFT
  • thin-film solar cells
  • XPS


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