Oriented Growth for Efficient and Scalable Perovskite Solar Cells by Vapor–Solid Reaction

Abstract The precise control and understanding of crystal orientation in perovskite polycrystalline films are crucial for the development of efficient and stable devices. However, achieving this control remains a significant challenge. Herein, a PbI₂ oriented growth strategy is developed, combined with in situ vapor–solid reaction transformations, to achieve oriented growth of full‐vacuum perovskite films. Grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) analysis revealed the general pattern of PbI₂ oriented vapor growth and in situ vapor–solid reaction transformation in this two‐step process. The resulting preferred orientation has effectively reduced trap state density, optimizing the carrier dynamics. As a result, champion efficiencies of 22.11% (0.148 cm²), 20.60% (1 cm²), and 19.41% (5 × 5 cm² mini‐modules) are achieved, which are the highest value for perovskite based on vapor–solid reaction. Additionally, the oriented growth method is applicable to a variety of guide layers and is extended to 30 × 30 cm² film, demonstrating the universality and scalability of the method.