Direct Measurements of Interfacial Photovoltage and Band Alignment in Perovskite Solar Cells Using Hard X-ray Photoelectron Spectroscopy

Sebastian Svanström, Alberto García Fernández, Tamara Sloboda, T. Jesper Jacobsson, Fuguo Zhang, Fredrik O.L. Johansson, Danilo Kühn, Denis Céolin, Jean Pascal Rueff, Licheng Sun, Kerttu Aitola, Håkan Rensmo*, Ute B. Cappel*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)
73 Downloads (Pure)

Abstract

A heterojunction is the key junction for charge extraction in many thin film solar cell technologies. However, the structure and band alignment of the heterojunction in the operating device are often difficult to predict from calculations and, due to the complexity and narrow thickness of the interface, are difficult to measure directly. In this study, we demonstrate a technique for direct measurement of the band alignment and interfacial electric field variations of a fully functional lead halide perovskite solar cell structure under operating conditions using hard X-ray photoelectron spectroscopy (HAXPES). We describe the design considerations required in both the solar cell devices and the measurement setup and show results for the perovskite, hole transport, and gold layers at the back contact of the solar cell. For the investigated design, the HAXPES measurements suggest that 70% of the photovoltage was generated at this back contact, distributed rather equally between the hole transport material/gold interface and the perovskite/hole transport material interface. In addition, we were also able to reconstruct the band alignment at the back contact at equilibrium in the dark and at open circuit under illumination.

Original languageEnglish
Pages (from-to)12485-12494
Number of pages10
JournalACS Applied Materials and Interfaces
Volume15
Issue number9
DOIs
Publication statusPublished - 8 Mar 2023
MoE publication typeA1 Journal article-refereed

Keywords

  • device design
  • experimental design
  • lead halide perovskite
  • operando measurements
  • photoelectron spectroscopy
  • photovoltaics
  • semiconductor physics
  • solar cell

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