RbPbI3 Seed Embedding in PbI2 Substrate Tailors the Facet Orientation and Crystallization Kinetics of Perovskites

Abstract High power conversion efficiencies (PCEs) in perovskite solar cells (PSCs) have always been awe‐inspiring, but perovskite films scalability is an exacting precondition for PSCs commercial deployment, generally unachievable through the antisolvent technique. On the contrary, in the two‐step sequential method, the perovskite's uncontrolled crystallization and unnecessary PbI 2 residue impede the device's performance. These two issues motivated to empower the PbI 2 substrate with orthorhombic RbPbI 3 crystal seeds, which act as grown nuclei and develop orientated perovskites lattice stacks, improving the perovskite films morphologically and reducing the PbI 2 content in eventual perovskite films. Thence, achieving a PCE of 24.17% with suppressed voltage losses and an impressive life span of 1140 h in the open air.