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Suppressing X‐Migrations and Enhancing the Phase Stability of Cubic FAPbX 3 (X = Br, I)
Author(s) -
Oranskaia Aleksandra,
Schwingenschlögl Udo
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201901411
Subject(s) - formamidinium , perovskite (structure) , materials science , hydrogen bond , halogen bond , perovskite solar cell , phase (matter) , steric effects , halogen , dopant , champion , crystallography , doping , stereochemistry , organic chemistry , chemistry , molecule , alkyl , optoelectronics , political science , law
Chemical bonding of formamidinium (FA) with the inorganic perovskite skeleton of FAPbX 3 (X = Br, I) is studied with emphasis on the differences to methylammonium: stronger hydrogen bonding, the presence of π‐anion bonding, and more sterically hindered motion inside the perovskite inorganic cage. Organic cation dopants fitting in the perovskite cubic cell and being capable of hydrogen and halogen bonding with overall doubled bonding strength as compared to FA are proposed. They are shown to suppress not only X‐migrations but also the undesirable α–δ phase transition of FAPbI 3 . In addition, a possible atomistic explanation of the champion solar cell efficiency achieved experimentally is developed.