Columnar Macrocyclic Molecule Tailored Grain Cage to Stabilize Inorganic Perovskite Solar Cells with Suppressed Halide Segregation

Abstract

Solidifying the soft lattice of all-inorganic mixed-halide perovskites is of great importance to restrain the notorious halide segregation under persistent light illumination. Herein, a multifunctional columnar macrocyclic molecule additive, namely cucurbituril into perovskite precursor to enhance the crystallization and reduce the defect density in the final perovskite film is introduced. Based on the theoretical calculation and simulation, the cucurbituril molecule with a strong double-ended negatively-charged cavity surrounded by terminated oxygen atoms not only coordinates with dangling Pb²⁺ ions to form host-guest complexation but also induces an electric dipole field at perovskite grain boundary to effectively repel the iodide ion migration from the inside grain to the defective boundary, significantly suppressing the halide segregation and improving the device performance. As a result, the carbon-based, all-inorganic CsPbI₂Br solar cell achieves an enhanced efficiency of 15.59% with great tolerance to environmental stresses. These findings provide new insights into the development of a novel passivation strategy with macrocyclic molecules for making high-efficiency and stable perovskite solar cells.