Single Crystals of Mixed-Cation Copper-Based Perovskite with Trimodal Bandgap Behavior

Amr Elattar, Wenhui Li, Hiroo Suzuki, Takashi Kambe, Takeshi Nishikawa, Aung Ko Ko Kyaw, Yasuhiko Hayashi

Research output: Contribution to journalArticlepeer-review


Two-dimensional (2D) hybrid perovskites with novel functionalities and structural diversity are a perfect platform for emerging optoelectronic devices such as photodetectors, light-emitting diodes, and solar cells. Here, we demonstrate that excess concentration of Cesium bromide (CsBr) is key to the formation of easily exfoliated 2D Cs2Cu(Cl/Br)4 perovskite crystal. Furthermore, by employing this trick to 2D perovskite MA2Cu(Cl/Br)4 (MA=methylammonium), we achieve a phase-pure easily exfoliated 2D mixed-cation (MA/Cs)2Cu(Cl/Br)4 perovskite crystal, which exhibits reduced bandgap (1.53 eV) with ferromagnetic behavior and photovoltaic property. The resultant mixed-cation structured device reveals enhanced efficiency compared to all MA and all Cs counterparts. These findings demonstrate the importance of cation-engineering in developing innovative materials with novel properties.

Original languageEnglish
Article numbere202104316
JournalChemistry - A European Journal
Issue number26
Publication statusPublished - May 6 2022


  • copper
  • exfoliation
  • mixed cation
  • perovskite
  • solar cells
  • two dimensional

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry


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