Conduction Band Tuning by Controlled Alloying of Fe into Cs2AgBiBr6 Double Perovskite Powders

Huygen J. Jöbsis, Kostas Fykouras, Joost W.C. Reinders, Jacco van Katwijk, Joren M. Dorresteijn, Tjom Arens, Ina Vollmer, Loreta A. Muscarella, Linn Leppert*, Eline M. Hutter*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)
31 Downloads (Pure)

Abstract

Halide double perovskite semiconductors such as Cs2AgBiBr6 are widely investigated as a more stable, less toxic alternative to lead-halide perovskites in light conversion applications including photovoltaics and photoredox catalysis. However, the relatively large and indirect bandgap of Cs2AgBiBr6 limits efficient sunlight absorption. Here, it is shown that controlled replacement of Bi3+ with Fe3+ via mechanochemical synthesis results in a remarkable tunable absorption onset between 2.1 and ≈1 eV. First-principles density functional theory (DFT) calculations suggest that this bandgap reduction originates primarily from a lowering of the conduction band upon the introduction of Fe3+, and predict a direct bandgap when >50% of Bi3+ is replaced with Fe3+. The tunability of the conduction band energy is found and reflected in the photoredox activity of these semiconductors. These findings open new avenues for enhancing the sunlight absorption of double perovskite semiconductors and for harnessing their full potential in sustainable energy applications.

Original languageEnglish
Article number2306106
JournalAdvanced functional materials
DOIs
Publication statusE-pub ahead of print/First online - 30 Aug 2023

Keywords

  • DFT calculations
  • double perovskites
  • electronic structures
  • mechanochemical synthesis
  • photocatalysis

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