Two‐Second‐Annealed 2D/3D Perovskite Films with Graded Energy Funnels and Toughened Heterointerfaces for Efficient and Durable Solar Cells

Abstract

AbstractThe 2D/3D perovskite heterostructures have been widely investigated to enhance the efficiency and stability of perovskite solar cells (PSCs). However, rational manipulation of phase distribution and energy level alignment in such 2D/3D perovskite hybrids are still of great challenge. Herein, we successfully achieved spontaneous phase alignment of 2D/3D perovskite heterostructures by concurrently introducing both 2D perovskite component and organic halide additive. The graded phase distribution of 2D perovskites with different n values and 3D perovskites induced favorable energy band alignment across the perovskite film and boosted the charge transfer at the relevant heterointerfaces. Moreover, the 2D perovskite component also acted as a “band‐aid” to simultaneously passivate the defects and release the residual tensile stress of perovskite films. Encouragingly, the blade‐coated PSCs based on only ≈2 s in‐situ fast annealed 2D/3D perovskite films with favorable energy funnels and toughened heterointerfaces achieved promising efficiencies of 22.5 %, accompanied by extended lifespan. To our knowledge, this is the highest reported efficiency for the PSCs fabricated with energy‐saved thermal treatment just within a few seconds, which also outperformed those state‐of‐the‐art annealing‐free analogues. Such a two‐second‐in‐situ‐annealing technique could save the energy cost by up to 99.6 % during device fabrication, which will grant its low‐coast implementation.