Enhanced Performance of Perovskite LEDs Fabricated in Ambient Air Assisted by Solvent Engineering

Metal halide perovskite light-emitting diodes (PeLEDs) have undergone rapid advancement, exhibiting enormous potential for next-generation display and lighting technologies. However, most high-performance devices are currently fabricated in inert atmospheres, and achieving high-efficiency fabrication in high-humidity ambient air remains a formidable challenge due to severe moisture interference. Herein, we report a solvent engineering strategy to overcome the obstacle of moisture and oxygen interference with crystallization kinetics in ambient air. Our investigation reveals that leveraging the strong Lewis base coordination between the N-methyl-2-pyrrolidone (NMP) solvent and the precursor, along with its better wettability to underlying substrates, effectively regulated the crystallization during the film formation and resulted in compact perovskite films with highly preferred crystallographic orientation with decreased trap states in comparison with commonly adopted dimethyl sulfoxide (DMSO). Consequently, the green PeLEDs fabricated under fully ambient conditions achieved a peak luminance of 10,700 cd/m 2 and an external quantum efficiency (EQE) of 1.33% without antisolvent assistance. These metrics are approximately one order of magnitude higher than those of the DMSO control, significantly outperforming those based on conventional solvent systems. This work unravels the regulatory role of solvent properties in the perovskite crystallization process in air, providing new insights for low-cost and simplified device fabrication technologies.