Strain Engineering of Metal Halide Perovskites on Coupling Anisotropic Behaviors

The power conversion efficiencies (PCEs) of the solar cells containing metal halide perovskites (MHPs) have rapidly increased and exceeded 25% during the past decade. The photovoltaic properties of these devices are extensively investigated in terms of their microstructures, environmental characteristics, and carrier dynamics, and the MHP structural evolution under high pressure is evaluated. In addition, the energy level structure, electron/hole dynamics, and optical/electronic properties of MHPs with anisotropic crystal structures are examined. However, the correlation between the structural anisotropy and material properties of these perovskites is rarely considered in the literature studies on their high‐pressure behavior. In this progress report, the optical/electronic properties of MHPs with anisotropic structures under thermal, mechanically imposed, and in‐service strains/stresses that have been previously neglected by researchers are summarized. Structural evolution of metal halide perovskites (MHPs) subjected to stress/strain induces the variation of optical and electronic properties. The in‐service performance and film stability of MHPs are deteriorated. By reviewing the evolution of structural related mechanical and opto‐electronic properties, strain engineering of MHPs coupling anisotropy to improve the performance of MHPs‐based devices is proposed.