Tilted‐Oriented 2D Perovskites for High‐Performance Solar Cells

Abstract Despite the high stability of 2D perovskites, high‐efficiency perovskite solar cells (PSCs) have predominantly been fabricated using pure 3D perovskites as the light‐absorbing layer. Introducing 2D perovskites into the 3D perovskite bulk typically leads to the formation of insulating spacer layers between conductive inorganic slabs, limiting the conductivity and charge transport of the 3D perovskite, thereby reducing device efficiency. This study demonstrates that these disadvantages associated with introducing 2D perovskites can be eliminated by tilting the 2D perovskite orientation. The thermodynamically stable tilted 2D perovskite orientation enhances the conductivity of 3D perovskites, improves film uniformity, and reduces defect concentration through grain boundary passivation. Additionally, the method used to induce this tilted 2D perovskite orientation does not influence the crystallization process of the highly optimized 3D perovskite. As a result, the best‐performing PSCs exhibit an efficiency of 26.6% (certified efficiency of 26.3%) under simulated solar illumination. Furthermore, encapsulated devices retain ≈90% of their initial efficiency even after 1100 h of operation under maximum power point tracking. These findings provide critical insights into overcoming the inherent limitations of conventional 2D perovskites, offering a pathway toward high‐efficiency and stable PSCs.