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 cm². 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 cm². Most impressively, uniform electroluminescence from an extra-large (16 cm²) 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.