A theoretical study of perovskites related to CH3NH3PbX3 (X = F, Cl, Br, I)

Abstract

The bond dissociation energies of MAPI (CH₃NH₃PbI₃) and related perovskites (with F, Cl, Br instead of I and with bases other than methylamine) have been calculated using a simplified model consisting of a corner of the perovskite (PbX₃⁻) and the methyl ammonium (CH₃NH₃⁺) and other protonated bases. The values obtained show that besides the size (related to the tolerance factor), the energy of the interaction should be considered. Using relativistic corrections (ADF), the ¹H, ¹³C, ¹⁵N and ²⁰⁷Pb absolute shieldings were calculated and transformed into chemical shifts by empirical equations established here. The ¹³C and ¹⁵N light nuclei were well reproduced by the “corner” model but the ²⁰⁷Pb chemical shifts need a large correction factor owing to the fact that lead in the perovskites is surrounded by six iodine atoms instead of the “corner's” three atoms.