Semi-Monolithic Integration of All-Chalcopyrite Multijunction Solar Conversion Devices via Thin-Film Bonding and Exfoliation

Kai Outlaw-Spruell, Joshua Crunk, Wilman Septina, Christopher Muzzillo, Kai Zhu, Nicolas Gaillard

Research output: Contribution to journalArticlepeer-review

2 Scopus Citations


We report on a semi-monolithic integration method to circumvent processing incompatibility between materials of dissimilar classes and combine them into multijunction devices for photovoltaic and photoelectrochemical applications. Proof-of-concept all-chalcopyrite tandems were obtained by consecutive transfer of fully integrated unpatterned 1.85 eV CuGa3Se5and 1.13 eV CuInGaSe2PV stacks from their Mo/soda lime glass substrates onto a new single host substrate. This transfer approach consists of two key steps: (1) bonding of the solar stack (face down) onto a handle (e.g., SnO2:F, FTO) using a transparent conductive composite and (2) delamination of the solar stack at the chalcopyrite/Mo interface by employing a wedge-based exfoliation technique. Upon transfer onto FTO, a CuGa3Se5champion device demonstrated near-coincident photocurrent density-voltage characteristic with a baseline measurement. Then, the exfoliated CuGa3Se5single-junction stack transferred onto FTO served as the new host onto which a second fully processed CuInGaSe2stack was bonded (face down) onto and liberated from its Mo/SLG substrate, leading to a complete transfer of both sub-cells onto one FTO substrate. A champion semi-monolithic tandem device exhibited a power conversion efficiency of 5.04% with an open-circuit voltage, a short-circuit current density, and a fill factor of 1.24 V, 7.19 mA/cm2, and 56.7%, respectively. This first-time demonstration of a fully operational semi-monolithic device provides a new avenue to combine thermally, mechanically, and/or chemically incompatible thin-film material classes into tandem photovoltaic and photoelectrochemical devices while maintaining state-of-the-art sub-cell processing.

Original languageAmerican English
Pages (from-to)54607-54615
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number49
StatePublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.

NREL Publication Number

  • NREL/JA-5K00-83220


  • chalcopyrite
  • Cu(In,Ga)Se
  • CuGaSe
  • multijunction devices
  • photoelectrochemical water splitting
  • photovoltaics
  • transparent conductive composites


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