It is challenging to achieve long‐term stability of perovskite solar cells due to the corrosion and diffusion of metal electrodes. Integration of compact barriers into devices has been recognized as an effective strategy to protect the perovskite absorber and electrode. However, the difficulty is to construct a thin layer of a few nanometers that can delay ion migration and impede chemical reactions simultaneously, in which the delicate microstructure design of a stable material plays an important role. Herein, ZrN_x barrier films with high amorphization are introduced in p–i–n perovskite solar cells. To quantify the amorphous–crystalline (a–c) density, pattern recognition techniques are employed. It is found the decreasing a–c interface in an amorphous film leads to dense atom arrangement and uniform distribution of chemical potential, which retards the interdiffusion at the interface between ions and metal atoms and protect the electrodes from corrosion. The resultant solar cells exhibit improved operational stability, which retains 88% of initial efficiency after continuous maximum power point tracking under 1‐Sun illumination at room temperature (25 °C) for 1500 h.