Figure 2.

(a) ¹H NMR spectrum of the reaction product of a BnAm and FAI mixture in DMSO-d₆. (b) ¹³C{¹H} NMR spectrum of the BnAm and FAI reaction mixture in DMSO-d₆. (c) HSQC spectrum of the solution. (d) Schematic of reaction between FAI and BnAm, yielding the Z-BnFA⁺ and E-BnFA⁺ isomers. (e) ToF-SIMS molecular distribution of perovskite film with 0.6 mol % of BnAm additive. See the molecular distribution of a control perovskite film in Figure S28. Note that the Pb–NH₃ fragment is absent in the control film.