Figure 4.
a) Schematic illustration of two neighboring grain structures in which the methyl ammonium groups are shown as one sphere for clarity, and the PbI6 4− octahedra are shown in red, crosslinked by butylphosphonic acid 4‐ABPACl hydrogen‐bonding interactions (O–H···I and N–H···I) of the iodide from the iodoplumbate complex with–PO(OH)2 and –NH3+ end groups of the 4‐ABPACl species. b) Surface and c) cross‐sectional SEM images of pristine (control) and 4‐ABPA‐anchored (CH3NH3PbI3–ABPA) perovskite films deposited on mesoscopic TiO2/FTO substrates by one‐step spin‐coating of the corresponding perovskite precursor solutions without or with 4‐ABPACl additive. a–c) Adapted with permission.73 Copyright 2015, Nature Publishing Group.