A new class of organic-inorganic single and double hybrid perovskites with a diammonium-halide-diammonium spacer layer

Hybrid organic-inorganic perovskites (HOIPs) can be molecularly engineered to exhibit diverse functionalities such as chirality, ferroelectricity and photovoltaics. To date, research on layered HOIPs has mostly focused on Ruddlesden-Popper (RP) or Dion-Jacobson (DJ) type structural motifs. From the viewpoint of synthetic chemistry, it is interesting to explore structural motifs beyond these well-studied classes using rational synthetic routes. Here we report the synthesis of a new family of layered HOIPs named diammonium-halide-diammonium (DHD) perovskites. A DHD perovskite is distinguished by its organic 'spacer' layer consisting of diammonium-halide-diammonium. Based on the DHD perovskite family, we have successfully synthesized the elusive iodide-based lead-free double perovskite systems. We present the key chemical and structural design considerations for Cu+/Bi3+ and Ag+/Bi3+ DHD double perovskite systems, using 3-aminopyrrolidinium (3AP) and ethylenediammonium (ED) as the organic A-site cation. Finally, ferroelectricity can be achieved by introducing chiral 3-aminopyrroline cations into the crystal structure, which demonstrates the structure flexibility and potential applications of this new class of perovskites. Hybrid organic-inorganic perovskites (HOIPs) can be molecularly engineered to exhibit diverse functionalities such as chirality, ferroelectricity and photovoltaics.

Automated summary

Hybrid organic-inorganic perovskites (HOIPs) have diverse functionalities such as chirality, ferroelectricity, and photovoltaics. This study focuses on a new family of layered HOIPs called diammonium-halide-diammonium (DHD) perovskites, which have an organic 'spacer' layer. The synthesis of lead-free double perovskite systems using DHD perovskites is also presented, with a discussion on the chemical and structural design considerations.