Mechanism of Solvent Engineering for Controlling the Room-Temperature Crystallization Kinetics of MAPbI₃ Perovskite Polycrystals

The realization of room-temperature preparation of the perovskite solar cells without a thermal annealing step could simplify the fabrication process and reduce the energy consumption. N,N-Dimethylacetamide (DMAc) is a promising candidate to replace N,N-dimethylformamide (DMF) as a perovskite precursor solvent with the advantage of room-temperature processability, while the influencing mechanism of DMAc and DMF solvents on controlling nucleation and crystallization kinetics has received limited attention. In light of this, we investigate the morphological structure and spectral properties of the perovskite films and verify the successful fabrication of high-quality alpha-phase perovskites from DMAc at room temperature. Further infrared and Raman spectroscopy reveals that the weakened interaction between DMAc and solutes helps perovskites to rapidly nucleate and crystallize from the solvent, promoting complete phase transformation to form a perovskite film. In situ UV-vis spectroscopy demonstrates the solvent effect on the crystallization kinetic process during film drying at room temperature. This work provides valuable insights into the preparation of high-quality perovskite films at room temperature, thereby driving the production of cost-effective perovskite devices.