RbPbI 3 Seed Embedding in PbI 2 Substrate Tailors the Facet Orientation and Crystallization Kinetics of Perovskites.

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.