  In recent years, organic-inorganic hybrid perovskites have attracted wide
attention due to their excellent optoelectronic properties in the application
of optoelectronic devices. In the manufacturing process of perovskite solar
cells, perovskite films inevitably have residual stress caused by
non-stoichiometry components and the external load. However, their effects on
the structural stability and photovoltaic performance of perovskite solar cells
are still not clear. In this work, we investigated the effects of external
strain on the structural stability and optoelectronic properties of tetragonal
MAPbI3 by using the first-principles calculations. We found that the migration
barrier of I- ion increases in the presence of compressive strain and decreases
with tensile strain, indicating that the compressive strain can enhance the
structural stability of halide perovskites. In addition, the light absorption
and electronic properties of MAPbI3 under compressive strain are also improved.
The variations of the band gap under triaxial and biaxial strains are
consistent within a certain range of strain, resulting from the fact that the
band edge positions are mainly influenced by the Pb-I bond in the equatorial
plane. Our results provide useful guidance for realizing the commercial
applications of MAPbI3-based perovskite solar cells.
