Band Gap Temperature-Dependence and Exciton-Like State in Copper Antimony Sulphide, CuSbS2

Andriy Zakutayev, Adam Welch, Max Birkett, Christopher Savory, Mohana Rajpalke, Wojciech Linhart, Thomas Whittles, James Gibbon, Ivona Mitrovic, David Scanlon, Tim Veal

Research output: Contribution to journalArticlepeer-review

15 Scopus Citations


The temperature-dependence of the band gap of the proposed photovoltaic absorber copper antimony sulphide (CuSbS2) has been studied by Fourier-transform infrared spectroscopy. The direct gap rises from 1.608 to 1.694 eV between 300 and 4.2 K. Below 200 K an exciton-like feature develops above the absorption edge at 1.82 eV. First-principles calculations evaluate band structure, band symmetries, and dipole selection rules, suggesting distinctly enhanced absorption for certain excitonic optical transitions. Striking consistency is seen between predicted dielectric and absorption spectra and those determined by ellipsometry, which reveal rapidly strengthening absorption passing 105 cm-1 at 2.2 eV. These results suggest beneficial photovoltaic performance due to strong optical absorption arising from unusually strong electron-hole interactions in polycrystalline CuSbS2 material.

Original languageAmerican English
Article number084904
Number of pages9
JournalAPL Materials
Issue number8
StatePublished - 2018

Bibliographical note

Publisher Copyright:
© 2018 Author(s).

NREL Publication Number

  • NREL/JA-5K00-71226


  • absorption spectroscopy
  • band gap
  • band structure
  • dielectrics
  • electromagnetic transitions
  • excitons
  • optical absorption
  • solar energy


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