The influence of compression on the lattice stability of α-FAPbI 3 revealed by numerical simulation

Compressive strain enables stable FA-based perovskites by suppressing the phase transition process. The ambient stability of α-FAPbI 3 perovskite remains one of the biggest barriers to its commercialization, despite many attempts to enhance its lifetime. Due to the difficulties in experimentally investigating the transition kinetics, numerical simulation was performed. Surprising results were uncovered that the unstable α phase could be maintained in ambient conditions under compression, caused by the reduced Gibbs free energy of this phase. By analysing the transition rate, the detailed kinetic parameters have also been obtained, enabling us to construct a more complete phase map as a function of temperature and stress, offering a possible path towards stable high PCE perovskite solar devices, which opens an unprecedented avenue in perovskite solar cell research, and will hopefully be of intrinsic interest to the broad materials research community as well.