Soft X-Ray Spectroscopy of a Complex Heterojunction in High-Efficiency Thin-Film Photovoltaics: Intermixing and Zn Speciation at the Zn(O,S)/Cu(In,Ga)Se2 Interface

Rebekah Garris, Lorelle Mansfield, Kannan Ramanathan, Michelle Mezher, Monika Blum, Dirk Hauschild, Kimberly Horsley, Douglas Duncan, Wanli Yang, Marcus Bar, Lothar Weinhardt, Clemens Heske

Research output: Contribution to journalArticlepeer-review

6 Scopus Citations

Abstract

The chemical structure of the Zn(O,S)/Cu(In,Ga)Se2 interface in high-efficiency photovoltaic devices is investigated using X-ray photoelectron and Auger electron spectroscopy, as well as soft X-ray emission spectroscopy. We find that the Ga/(Ga+In) ratio at the absorber surface does not change with the formation of the Zn(O,S)/Cu(In,Ga)Se2 interface. Furthermore, we find evidence for Zn in multiple bonding environments, including ZnS, ZnO, Zn(OH)2, and ZnSe. We also observe dehydrogenation of the Zn(O,S) buffer layer after Ar+ ion treatment. Similar to high-efficiency CdS/Cu(In,Ga)Se2 devices, intermixing occurs at the interface, with diffusion of Se into the buffer, and the formation of S - In and/or S - Ga bonds at or close to the interface.

Original languageAmerican English
Pages (from-to)33256-33263
Number of pages8
JournalACS Applied Materials and Interfaces
Volume8
Issue number48
DOIs
StatePublished - 7 Dec 2016

Bibliographical note

Publisher Copyright:
© 2016 American Chemical Society.

NREL Publication Number

  • NREL/JA-5K00-67637

Keywords

  • alternative buffer layers
  • chalcopyrite thin-film solar cell
  • chemical structure
  • X-ray emission spectroscopy
  • X-ray photoelectron spectroscopy
  • Zn(O,S)

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