Seed‑ and Vacuum‑Assisted, Anti‑Solvent‑Free Crystallization for Uniform Perovskite Mini‑Modules

Scaling perovskite solar cells into efficient modules requires uniform, highly crystalline absorber layers, but conventional anti‑solvent processing is difficult to control and environmentally problematic at large area. Here, I present a seed‑ and vacuum‑assisted crystallization (S‑VAC) method that enables anti‑solvent‑free deposition of monolithic perovskite films on 15 × 15 cm substrates for inverted p‑i‑n mini‑modules. Oleylamine additives generate ~1.7 nm α‑phase nanocrystal seeds in the precursor via hydrogen bonding with formamidinium cations and steric stabilization of the alkyl chain. Low‑pressure vacuum drying converts these seeds into vertically aligned grains with strong (100) texture while ensuring homogeneous thickness without chlorinated anti‑solvents.

Time‑resolved GIWAXS, NMR, dynamic light scattering, TEM, and infrared photo‑induced force microscopy correlate oleylamine‑driven seed formation with enhanced FA vibrational ordering, improved lattice alignment, and suppressed halide phase segregation. Devices based on S‑VAC films deliver 23.2% power conversion efficiency (PCE) for 2.5 × 2.5 cm cells and a certified 19.1% PCE for 15 × 15 cm mini‑modules, establishing a high scalable performance index among anti‑solvent‑free perovskite modules. Encapsulated modules retain 94% of their initial efficiency after 500 h ISOS‑L‑1 testing and maintain stable output for over one year under outdoor ISOS‑O‑3 conditions. This student‑led work demonstrates that molecularly engineered seed‑assisted vacuum crystallization can simultaneously deliver efficiency, scalability, and durability for perovskite module manufacturing.