Interface stoichiometry control to improve device voltage and modify band alignment in ZnO/Cu2O heterojunction solar cells

Samantha S. Wilson, Jeffrey P. Bosco, Yulia Tolstova, David O. Scanlon, Graeme W. Watson, Harry A. Atwater*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The interface stoichiometry of cuprous oxide (Cu2O) was controlled by adjusting the O2 and Zn partial pressures during ZnO sputter deposition and measured by high-resolution X-ray photoelectron spectroscopy of ultrathin (<3 nm) ZnO films on Cu2O. Open-circuit voltage measurements for ZnO/Cu2O heterojunctions under AM1.5 illumination were measured and it was found that a stoichiometric interface can achieve the voltage entitlement dictated by the band alignment, whereas the non-stoichiometric interface showed large open-circuit voltage deficits. These results highlight not only the need for stoichiometric interfaces in Cu2O devices, but also a reproducible experimental method for achieving stoichiometric interfaces that could be applied to any potential heterojunction partner. Additionally, valence-band offset measurements indicated changing the interface stoichiometry shifted the band alignment between Cu2O and ZnO, which accounts for the variation in previously reported band offset values.

Original languageEnglish
Pages (from-to)3606-3610
Number of pages5
JournalEnergy and Environmental Science
Volume7
Issue number11
DOIs
Publication statusPublished - 1 Nov 2014

Bibliographical note

Publisher Copyright:
© 2014 the Partner Organisations.

ASJC Scopus subject areas

  • Environmental Chemistry
  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Pollution

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