Methylamine-Dimer-Induced Phase Transition toward MAPbI Films and High-Efficiency Perovskite Solar Modules.

Perovskite films prepared with CHNH 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 CHNH-CHNHPbI was analyzed to involve hydrogen bonds (CHNH···CHNH) and has guided the facile, reproducible preparation of high-quality perovskite films under ambient conditions. Hydrogen bonds within CHNH···CHNH dimers were found in the CHNH-CHNHPbI intermediates, accompanied by 1D-PbI chains (δ-phase). The weakly hydrogen-bonded CHNH molecules were easily released from the CHNH-CHNHPbI intermediates, contributing to rapid, spontaneous phase transition from 1D-PbI (δ-phase) to 3D-PbI (α-phase). Further introduction of CHNHCl into the CHNH-CHNHPbI intermediates led to interruption of 1D-PbI transition into 0D-PbICl(0 < < 6), adjusting the phase transition route toward 3D-PbI. On the basis of the above understanding, CHNH solution in ethanol and CHNHCl were used for precursors and a best efficiency of 20.3% in PSCs was achieved. Large-scale modules (12 cm 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.