Controlling Nucleation Kinetics Via Co‐Solvent Strategy for High‐Quality Perovskite Films and Large‐Area Light‐Emitting Diodes

Perovskite light‐emitting diodes (PeLEDs), particularly blue‐emitting PeLEDs, achieve remarkable progress and demonstrate immense potential for next‐generation displays and lighting. However, stability limitations and challenges in fabricating large‐area, high‐quality perovskite films remain critical barriers to commercialization. Inspired by rapid evaporation techniques, a novel solvent engineering strategy is developed. A co‐solvent system of dimethyl sulfoxide (DMSO) and 2‐methoxyethanol (2‐Me), synergized with flash evaporation, dramatically accelerates solvent removal and promotes rapid heterogeneous nucleation—precisely controlling perovskite nucleation kinetics. As a result, the prepared high‐efficiency sky‐blue PeLED achieves an external quantum efficiency (EQE) of 20.5% at 0.1 cm 2 . Consequently, large‐area, high‐quality perovskite films are successfully prepared via blade‐coating, and a notable EQE of 9.4% is also achieved at 2 cm 2 . Most impressively, uniform electroluminescence from an extra‐large (16 cm 2 ) PeLED is demonstrated. This solvent engineering strategy eliminates the need for toxic anti‐solvents and enables a simplified large‐area processing technique, representing a significant step toward the industrialization of high‐performance PeLEDs.