Self-Seeding Growth for Perovskite Solar Cells with Enhanced Stability

Hybrid organic-inorganic lead halide perovskite solar cells have shown a remarkable rise in power conversion efficiency over a short period of time; however, long-term stability remains a key challenge hindering the practical application of these cells. Here, we report an approach to sequentially apply a typical one-step solution formulation-self-seeding growth (SSG)-to realize highquality perovskite thin films with reduced defect density, fewer apparent grain boundaries, improved charge-carrier transport and lifetime, and enhanced hydrophobicity for enhanced stability. Using FA-MA-Cs-based perovskite, SSG devices showed improved efficiency from 17.76% (control) to 20.30% (SSG), with an unencapsulated device retaining > 80% of its initial efficiency over 4,680-h storage in an ambient environment with high relative humidities. The SSG devices also exhibited much improved thermal and operational stabilities. In addition, SSG can be applied to different substrates and perovskite compositions, which makes it a viable method for preparing high-quality perovskite thin films for device applications.