Air‐Processed Blue Perovskite Light‐Emitting Diodes Enabled by Manipulation of Adsorbed‐Moisture‐Dominated Crystallization Kinetics

Abstract The fabrication of blue perovskite light‐emitting diodes (PeLEDs) in air conditions promises to liberate the manipulation procedures from the protection of inert atmosphere in the glovebox, which will remarkably promote the commercialization proceeding of perovskite‐based optoelectronic devices in display applications. However, achieving air‐processed blue PeLEDs in the interference of moisture meets great challenges in crystallization kinetics control. Herein, it is proposed that substrate‐adsorbed moisture dominates the perovskite crystallization kinetics during the fabrication in air, and the limited moisture from nonhygroscopic substrate inhibits the nucleation of the large‐ n phase and allows the growth of the small‐ n phase, thus yielding blue quasi‐2D perovskite films in a wide moisture range of 10–50% relative humidity. Then, air‐processed blue PeLEDs are successfully achieved for the first time, showing a brightness of 968 cd m −2 , external quantum efficiency of 2.54% at stable peak emission of 483 nm, as well as an outstanding operating stability of 546 s at a peak brightness of 45 cd m −2 , which are favorably competitive with PeLEDs fabricated in the glovebox. This work provides a guideline for air‐processed blue PeLEDs fabrication, which paves the way for air‐processed PeLEDs in further application of commercialization display.