Enhancing the chemical flexibility of hybrid perovskites by introducing divalent ligands

Abstract

Herein we report the synthesis and structures of [(CH₃)₂NH₂]Er(HCO₂)₂(C₂O₄) and [(NH₂)₃C]Er(HCO₂)₂(C₂O₄), in which the inclusion of divalent oxalate ligands allows for the exclusive incorporation of A⁺ and B³⁺ cations in an ABX₃ hybrid perovskite structure for the first time. We rationalise the observed thermal expansion of these materials, including negative thermal expansion, and find evidence for weak antiferromagnetic coupling in [(CH₃)₂NH₂]Er(HCO₂)₂(C₂O₄).