Fig. 1. (Color online) (a) Deprotonation of MA⁺ and FA⁺. Reproduced with permission^[14], Copyright 2021, American Chemical Society. (b) The addition-elimination reaction of MA and FAI in perovskite precursor solution. Reproduced with permission^[13], Copyright 2020, Elsevier. (c) The amine-cation reactions between MA and FA⁺ and between FA and MA⁺. Gibbs free energy profiles for MA−FA⁺ reaction (d) and FA−MA⁺ reaction (e). Reproduced with permission^[14], Copyright 2022, American Chemical Society.

Fig. 2. (Color online) (a) Photos for solutions with and without DHP. Reproduced with permission^[16], Copyright 2022, Wiley. (b) Mechanism for S₈ to stabilize precursor solution. Reproduced with permission^[18], Copyright 2019, Wiley. (c) Photos for films from precursor solution with and without ITIC-Th. Reproduced with permission^[19], Copyright 2018, Wiley. (d) Schiff-base reaction between organic amine and aldehyde. Reproduced with permission^[14], Copyright 2021, American Chemical Society. (e) Schematic for BHC reducing I₂/I₃^– to I^– during the ageing of solution. Reproduced with permission^[15], Copyright 2021, Science (AAAS). (f) Mechanism for 3-HBA to inhibit the degradation of perovskite precursor solution. Reproduced with permission^[22], Copyright 2022, Wiley.