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Title: 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)Se 2 interface

In this study, the chemical structure of the Zn(O,S)/Cu(In,Ga)Se 2 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)Se 2 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)Se 2 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.
Authors:
 [1] ;  [2] ;  [2] ;  [1] ;  [3] ;  [1] ;  [1] ;  [4] ;  [5] ;  [6] ;  [2] ;  [6]
  1. Univ. of Nevada, Las Vegas (UNLV), Las Vegas, NV (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany); Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  5. Univ. of Nevada, Las Vegas (UNLV), Las Vegas, NV (United States); Helmholtz-Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Brandenburgische Technische Univ. Cottbus-Senftenberg, Cottbus (Germany)
  6. Univ. of Nevada, Las Vegas (UNLV), Las Vegas, NV (United States); Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany); Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany)
Publication Date:
Report Number(s):
NREL/JA-5K00-67637
Journal ID: ISSN 1944-8244
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 8; Journal Issue: 48; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S); SunShot Foundational Program to Advance Cell Efficiency (F-PACE)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; alternative buffer layers; chalcopyrite thin-film solar cell; chemical structure; X-ray emission spectroscopy; X-ray photoelectron spectroscopy; Zn(O,S)
OSTI Identifier:
1337540