Multi-environment phase stabilization by lattice reinforcement for efficient perovskite solar cells

Formamidine (FA)-rich perovskite solar cells (PSCs) display high competitiveness for commercial applications due to their excellent thermal stability and wide spectral absorption. However, an undesired phase transition is induced in FA-rich PSCs through an excessively distorted crystal lattice, which is considerably controlled by residual stress. In this work, by constructing a series of lattice-reinforced structures, the differential interaction between the organic spacer cations and inorganic octahedra is verified. Furthermore, by exploring the transition processes of α-phase to -β-phase and δ-phase, the importance of the relationship between the residual stress release and lattice reinforcement is revealed. Finally, the phenmethylammonium-treated device exhibits an outstanding photoelectric conversion efficiency (PCE) of 22.90% with a suppressed multipath phase transition, and can maintain 90% of its initial performance after being placed in the air for 1000 h. Additionally, a PCE of 17.10% is achieved on a mini-module with a 25-cm2 substrate, verifying its feasible upscaling fabrication.