Perovskite
films prepared with CH3NH2 molecules
under ambient conditions have led to rapid fabrication of perovskite
solar cells (PSCs), but there remains a lack of mechanistic studies
and inconsistencies with operability in their production. Here the
crystal structure of CH3NH2–CH3NH3PbI3 was analyzed to involve hydrogen bonds
(CH3NH2···CH3NH3+) and has guided the facile, reproducible preparation
of high-quality perovskite films under ambient conditions. Hydrogen
bonds within CH3NH2···CH3NH3+ dimers were found in the CH3NH2–CH3NH3PbI3 intermediates, accompanied by 1D-PbI3– chains (δ-phase). The weakly hydrogen-bonded CH3NH2 molecules were easily released from the CH3NH2–CH3NH3PbI3 intermediates, contributing to rapid, spontaneous phase transition
from 1D-PbI3– (δ-phase) to 3D-PbI3– (α-phase). Further introduction
of CH3NH3Cl into the CH3NH2–CH3NH3PbI3 intermediates
led to interruption of 1D-PbI3– transition
into 0D-Pb2I9‑xClx5–(0 < x < 6), adjusting the phase transition route toward 3D-PbI3–. On the basis of the above understanding,
CH3NH2 solution in ethanol and CH3NH3Cl were used for precursors and a best efficiency of
20.3% in PSCs was achieved. Large-scale modules (12 cm2 aperture area) fabricated by a dip-coating technology exhibited
an efficiency up to 16.0% and outstanding stability over 10 000
s under continuous output. The developed preparation method of perovskite
precursors and insightful research into the methylamine-dimer-induced
phase transition mechanism have enabled the production of high-quality
perovskite films with robust operability, showing great potential
for large-scale commercialization.