Chemical and electronic structure of the heavily intermixed (Cd,Zn)S:Ga/CuSbS2 interface

Claudia Hartmann, Riley Brandt, Lauryn Baranowski, Leonard Kohler, Evelyn Handick, Roberto Felix, Regan Wilks, Andriy Zakutayev, Tonio Buonassisi, Marcus Bar

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The interface formation and chemical and electronic structure of the (Cd,Zn)S:Ga/CuSbS2 thin-film solar cell heterojunction were studied using hard X-ray photoelectron spectroscopy (HAXPES) of the bare absorber and a buffer/absorber sample set for which the buffer thickness was varied between 1 and 50 nm. We find a heavily intermixed interface, involving Cu, Zn, and Cd as well as significant Ga and Cu profiles in the buffer. The valence band (VB) offset at the buffer/absorber interface was derived as (−1.3 ± 0.1) eV, which must be considered an upper bound as the Cu diffused into the buffer might form a Cu-derived VB maximum located closer to the Fermi level. The estimated conduction band minimum was ‘cliff’-like; a situation made more severe considering the Cu-deficiency found for the CuSbS2 surface. The complex interface structure’s effect on the performance of (Cd,Zn)S:Ga/CuSbS2-based solar cells and its limitation is discussed together with possible mitigation strategies.

Original languageAmerican English
Pages (from-to)130-145
Number of pages16
JournalFaraday Discussions
StatePublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 The Royal Society of Chemistry.

NREL Publication Number

  • NREL/JA-5K00-83090


  • absorber
  • buffer
  • interface


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