Supramolecular Interactions of Flexible 2D Perovskite in Microstrain Releasing and Optoelectronic Properties Recovery

Abstract The conductivity of 2D perovskite is mainly dominated by halide metal octahedron skeletons. However, in contrast to 3D perovskite structures, the layered inorganic skeletons are easily compressed or stretched by large organic cations, causing serious microstrain with impaired optoelectronic responses. Here, fluorination modulated supramolecular interactions in 2D fluorophenethylammonium lead iodide (FPEA₂PbI₄) perovskites are reported. In the double layered organic spacer, interlayer supramolecular interactions between electronegative F atoms and electron‐rich benzene rings dominate the lattice microstrain of 2D (p‐FPEA)₂PbI₄ perovskite, which can be released by interlayer interactions pulling during compressively bending the flexible devices. This strong electrostatic interaction can maximally release the compression to the inorganic octahedron skeleton during compressive bending, leading to a maximum degree of released microstrain with improved stability. The 60% microstrain can be released by compressive bending, and the corresponding photocurrent response is recovered by about three times in (p‐FPEA)₂PbI₄ perovskite film. In contrast, intralayer supramolecular interactions dominate microstrain of 2D (o‐FPEA)₂PbI₄ perovskites, which prevents the microstrain release during compressive bending. The strong electrostatic interaction design in the organic spacer of 2D perovskite takes an important role in releasing the microstrain and re‐bursting the device performance of flexible perovskite devices.