Defect Passivation Strategies in Two‐Dimensional Organic–Inorganic Hybrid Perovskites for Enhanced Photoelectric Performance

Abstract The polycrystalline perovskite films treated with solutions inevitably are subjected to high‐density crystal defects, significantly affecting the performance and stability of perovskite‐based photodetectors. In this research, a reasonably designed organic small molecule using piperazine iodide (PI) as an additive is employed to modify the perovskite films. The results indicate that this designed molecule not only improves the crystallinity of the perovskite film but also effectively passivates defects by modifying the local electron density. Consequently, recombination of non‐radiation charges is inhibited, improving the optoelectronic performance and stability of the device. The modified flexible photoelectric device exhibits a responsivity of 3.07 mA W −1 under 405 nm laser illumination. Notably, it maintains a high responsivity even after 7000 bending cycles. Furthermore, generality of the strategy is verified by applying it to various types of two‐dimensional organic–inorganic hybrid perovskite. Additionally, another small molecular amine phthalimide (PTM) is selected as an additive to further verify the universality of this strategy, which reveals that it demonstrates the same passivation as PI. This strategy provides a novel idea for defect passivation of two‐dimensional organic–inorganic hybrid perovskite, signifying a practical application significance for developing flexible wearable devices with optimized performance, perovskite light‐emitting diodes, and solar cells.