Impact of Interface Energetic Alignment and Mobile Ions on Charge Carrier Accumulation and Extraction in p-i-n Perovskite Solar Cells

Weidong Xu, Lucy J.F. Hart, Benjamin Moss, Pietro Caprioglio, Thomas J. Macdonald, Francesco Furlan, Julianna Panidi, Robert D.J. Oliver, Richard A. Pacalaj, Martin Heeney, Nicola Gasparini, Henry J. Snaith, Piers R.F. Barnes*, James R. Durrant*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Understanding the kinetic competition between charge extraction and recombination, and how this is impacted by mobile ions, remains a key challenge in perovskite solar cells (PSCs). Here, this issue is addressed by combining operando photoluminescence (PL) measurements, which allow the measurement of real-time PL spectra during current–voltage (J–V) scans under 1-sun equivalent illumination, with the results of drift-diffusion simulations. This operando PL analysis allows direct comparison between the internal performance (recombination currents and quasi-Fermi-level-splitting (QFLS)) and the external performance (J–V) of a PSC during operation. Analyses of four PSCs with different electron transport materials (ETMs) quantify how a deeper ETM LUMO induces greater interfacial recombination, while a shallower LUMO impedes charge extraction. Furthermore, it is found that a low ETM mobility leads to charge accumulation in the perovskite under short-circuit conditions. However, thisalone cannot explain the remarkably high short-circuit QFLS of over 1 eV which is observed in all devices. Instead, drift-diffusion simulations allow this effect to be assigned to the presence of mobile ions which screen the internal electric field at short-circuit and lead to a reduction in the short-circuit current density by over 2 mA cm−2 in the best device.

Original languageEnglish (US)
Article number2301102
JournalAdvanced Energy Materials
Volume13
Issue number36
DOIs
StatePublished - Sep 22 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors. Advanced Energy Materials published by Wiley-VCH GmbH.

Keywords

  • charge accumulation
  • charge extraction
  • drift-diffusion simulation
  • ion migration
  • operando photoluminescence spectroscopy
  • perovskite solar cells
  • quasi-Fermi level splitting

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • General Materials Science

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