Tailoring crystallization kinetics for scalable and efficient large-area perovskite light-emitting diodes

Scalable fabrication of uniform perovskite films is a critical bottleneck for large-area perovskite light-emitting diodes (PeLEDs), hindered by coffee-ring formation and heterogeneous crystallization upon scaling. Here, we report a multimodal solvent-engineering strategy enabling highly uniform films via ambient blade coating combined with vacuum-assisted solvent evaporation. Incorporating N-methyl-2-pyrrolidone (NMP) and acetonitrile (ACN) into a dimethylformamide (DMF)-based system synergistically modulates evaporation dynamics: It suppresses macroscopic solute segregation through Marangoni flow-induced redistribution, while tuning precursor coordination to regulate nucleation/phase conversion and promote radiatively efficient film formation. Consequently, the ternary formulation yields films with improved uniformity, reduced trap densities, and enhanced radiative efficiency. Near-infrared (NIR) PeLEDs achieve peak external quantum efficiencies of 25.2% (10 mm²), 22.1% (60 mm²), and 19.0% (224 mm²). A functional vein-imaging prototype is also demonstrated using a 224-mm² device, highlighting the impact for large-area optoelectronic applications.