Deciphering electron interplay at the Fullerene/Sputtered TiOxInterface: a barrier-free electron extraction for organic solar cells

Dylan Amelot, Mehrad Ahmadpour, Quim Ros, Hervé Cruguel, Nicolas Casaretto, Albano Cossaro, Luca Floreano, Morten Madsen, Nadine Witkowski*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Organic photovoltaics (OPVs) technology now offers power conversion efficiency (PCE) of over 18% and is one of the main emerging photovoltaic technologies. In such devices, titanium dioxide (TiOx) has been vastly used as an electron extraction layer, typically showing unwanted charge-extraction barriers and the need for light-soaking. In the present work, using advanced photoemission spectroscopies, we investigate the electronic interplay at the interface between low-temperature-sputtered TiOx and C70 acceptor fullerene molecules. We show that defect states in the band gap of TiOx are quenched by C70 while an interfacial state appears. This new interfacial state is expected to support the favorable energy band alignment observed, showing a perfect match of transport levels, and thus barrier-free extraction of charges, making low-temperature-sputtered TiOx a good candidate for the next generation of organic solar cells.

Original languageEnglish
JournalACS Applied Materials and Interfaces
Volume13
Issue number16
Pages (from-to)19460-19466
ISSN1944-8244
DOIs
Publication statusPublished - 28. Apr 2021

Bibliographical note

Publisher Copyright:
© 2021 American Chemical Society.

Keywords

  • fullerene
  • gap state
  • interface state
  • light-soaking
  • organic solar cell
  • resonant photoemission
  • titanium dioxide

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