Fig. 31.

Atomic substitution in 3D materials. a Schematic diagram showing the transformation of 2D mixed HFA_xMA_1-xPbI₃Cl into 3D FA_xMA_1-xPbI₃ (MA = methylammonium, FA = formamidinium). Reproduced with permission [203].

Copyright 2016, John Wiley and Sons. b Illustration showing the preparation of compositionally graded mixed-cation lead mix-halide perovskite absorbers. Reproduced with permission [204]. Copyright 2018, John Wiley and Sons. c, d Atomic structure and optical images of MAPbBr₃/MAPbI₃ heterostructures. Reproduced with permission [205]. Copyright 2016, American Chemical Society. e MA-mediation synthesis of FA_1−xMA_xPbI₃ mixed-organic-cation iodide perovskite from MA⁺-excess precursor solutions. X⁻ denotes an anion that does not conform with the structure. Reproduced with permission [206]. Copyright 2017, John Wiley and Sons