Lead‐Free Halide Double Perovskite Cs2AgBiBr6 with Decreased Bandgap

Fuxiang Ji, Johan Klarbring, Feng Wang, Weihua Ning*, Linqin Wang, Chunyang Yin, José Silvestre, Mendoza Figueroa, Christian Kolle Christensen, Martin Etter, Thomas Ederth, Licheng Sun, Sergei Simak, Igor Abrikosov, Feng Gao*

*Corresponding author for this work

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Environmentally friendly halide double perovskites with improved stability are regarded as a promising alternative to lead halide perovskites. The benchmark double perovskite, Cs 2 AgBiBr 6 , shows attractive optical and electronic features, making it promising for high-efficiency optoelectronic devices. However, the large band gap limits its further applications, especially for photovoltaics. Herein, we develop a novel crystal-engineering strategy to significantly decrease the band gap by approximately 0.26 eV, reaching the smallest reported band gap of 1.72 eV for Cs 2 AgBiBr 6 under ambient conditions. The band-gap narrowing is confirmed by both absorption and photoluminescence measurements. Our first-principles calculations indicate that enhanced Ag-Bi disorder has a large impact on the band structure and decreases the band gap, providing a possible explanation of the observed band-gap narrowing effect. This work provides new insights for achieving lead-free double perovskites with suitable band gaps for optoelectronic applications.

Original languageEnglish
JournalAngewandte Chemie International Edition
Issue number35
Pages (from-to)15191-15194
Publication statusPublished - 24. Aug 2020
Externally publishedYes


  • Ag–Bi disorder
  • Cs AgBiBr
  • band-gap engineering
  • crystal engineering
  • lead-free double perovskites


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