Traps in the spotlight: How traps affect the charge carrier dynamics in Cs2AgBiBr6 perovskite

Valentina M. Caselli, Jos Thieme, Huygen J. Jöbsis, Sohan A. Phadke, Jiashang Zhao, Eline M. Hutter, Tom J. Savenije*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)
21 Downloads (Pure)

Abstract

Suitable optoelectronic properties of lead halide perovskites make these materials interesting semiconductors for many applications. Toxic lead can be substituted by combining monovalent and trivalent cations, such as in Cs2AgBiBr6. However, efficiencies of Cs2AgBiBr6-based photovoltaics are still modest. To elucidate the loss mechanisms, in this report, we investigate charge dynamics in Cs2AgBiBr6 films by double-pulse excitation time-resolved microwave conductivity (DPE-TRMC). By exciting the sample with two laser pulses with identical wavelengths, we found a clear photoconductance enhancement induced by the second pulse even 30 μs after the first laser pulse. Modeling the DPE-TRMC results, complemented by photoluminescence and transient absorption, we reveal the presence of deep emissive electron traps, while shallow hole trapping is responsible for the long-lived transient absorption signals. These long-lived carriers offer interesting possibilities for X-ray detectors or photocatalysis. The DPE-TRMC methodology offers unique insight into the times involved in charge trapping and depopulation in Cs2AgBiBr6.

Original languageEnglish
Article number101055
Number of pages16
JournalCell Reports Physical Science
Volume3
Issue number10
DOIs
Publication statusPublished - 2022

Keywords

  • charge carrier dynamics
  • double-pulse excitation
  • excitons
  • lead-free perovskites
  • photoluminescence
  • thin film
  • time-resolved microwave conductance
  • transient absorption
  • trap states

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