Conformal Imidazolium 1D Perovskite Capping Layer Stabilized 3D Perovskite Films for Efficient Solar Modules

Although the perovskite solar cells have been developed rapidly, the industrialization of perovskite photovoltaics is still facing challenges, especially considering their stability issues. Here, the new type of benzimidazolium salt, N,N′‐dialkylbenzimidazolium iodide, is proposed and functionalized to convert the three‐dimensional (3D) FACs‐perovskite films into one‐dimensional (1D) capping layer topped 1D/3D structure either in individual device or module levels. This conformal interface modulation demonstrates that not only can effectively stabilize FACs‐based perovskite films by inhibiting the lateral and vertical iodide diffusions in devices or modules, ensuring an excellent operation and environmental stability, but also provides an excellent charge transporting channel through the well‐designed 1D crystal structure. Consequently, efficient device performance with power conversion efficiency up to 24.3% is readily achieved. And the large‐area perovskite solar modules with high efficiency (19.6% for the active areas of 18 cm(2)) and long‐term stability (about 500 h in AM 1.5G illumination or about 1000 h under double‐85 conditions) are also successfully verified.