Octahedral perovskite materials with small radius metal center and uses thereof

Abstract

Ge-centered octahedral perovskites have heretofore not been achievable due to collapse of the perovskite structure into non-octahedral units due to a lack of B site support from the small-radius Ge atom, which breaks Goldschmidt's rules for constructing octahedral perovskites. To overcome this shortcoming, a strategy was developed to form a strong cage with the A sites in which the octahedron is forced to remain intact. Strong intermolecular interaction between the organic A site cations were used to stabilize the symmetric Ge octahedral perovskite beyond the Goldschmidt's rules. The molecules used based on Y-PMA (Y: F, Cl, Br, I) that facilitated strong halogen bonding to form the cage around the octahedral. Octahedral Ge perovskites exhibit a direct bandgap in contrast to the indirect bandgap of non-octahedral Ge perovskites are demonstrated. In addition, the octahedral Ge perovskite exhibited a dramatic increase in the carrier mobility. A photodetector made with the stabilized octahedral perovskite material exhibited a vastly better responsivity than non-octahedral Ge perovskites.