Homoepitaxial Seed‐Mediated Growth for High‐Efficiency FAPbI 3 Perovskite Solar Cells

Seed‐mediated growth has emerged as a pivotal strategy for fabricating high‐efficiency perovskite solar cells (PSCs), particularly when perovskite nanocrystals (PNCs) with identical structural configurations are utilized as the seeds. Although homogenous seed‐mediated growth is recognized as a feasible and effective strategy, research on high‐quality PNCs serving as seeds remains limited, largely constrained by the inherent poor stability of iodine‐based perovskite PNCs. To address this challenge, we incorporate cyclohexylamine (CA) molecules to enhance the stability and optical properties of FAPbI 3 and CsPbI 3 PNCs, thereby enabling their utilization as alternative seed candidates for fabricating FAPbI 3 perovskite films. The PNCs sharing the same composition (FAPbI 3 PNCs) facilitate fully lattice‐matched homogeneous growth, thereby promoting the fabrication of high‐quality perovskite films featuring larger grain sizes, reduced defect densities, and more favorable energy level alignment. Consequently, the power conversion efficiency (PCE) of the resultant PSCs is boosted from 22.35% to 25.55%. Furthermore, the stability of the fabricated PSCs has been elevated, retaining 92.4% of their initial efficiency after 3 months of storage in an ambient atmosphere. This strategy not only facilitates the fabrication of high‐quality perovskite films but also provides a promising alternative for designing high‐performance seed‐induced growth systems in the field of perovskite photovoltaics.