Optimizing Emission Stability in Blue Perovskite Light‐Emitting Diodes via Oxygen‐Plasma Treatment of NixOy Hole Transport Layer

Currently, wide‐color gamut perovskite light‐emitting diodes (PeLEDs) are commonly controlled through halide composition tuning. However, the formation of perovskite crystals involving different ion radii of halogens often results in structural fragility and ionic defects, leading to emission instability during operation. This study showcases a novel approach to achieving a homogeneous and low‐defect crystalline state by regulating the thermodynamic nucleation mechanism of sky‐blue perovskite, thereby enhancing emission stability. Utilizing oxygen‐plasma treatment, a highly uniform surface energy is ensured for the nickel oxide acting as a hole transport layer. This treatment not only induces homogeneous nucleation of the perovskite layer but also effectively suppresses crystal defects. Simultaneously, the uniform surface energy alleviates halide phase separation caused by Ostwald ripening. Upon optimizing the fabrication conditions for sky‐blue perovskite, the resulting PeLEDs, featuring an electroluminescent peak at 486 nm, attain a luminance of 1125.3 cd m−2 with exceptional electroluminescent stability and a T50 lifetime. Furthermore, gaining insights into the thermodynamic nucleation mechanism in mix‐halides and perovskites contributes to the advancement of research on sky‐blue PeLEDs and offers valuable perspectives for future development. This study demonstrates that the hole transport layer of NixOy is used in perovskite light‐emitting diodes (PeLEDs) with uniform surface energy and deep valence band through the oxygen‐plasma treatment that enhances the long‐acting device performance. Furthermore, the study highlights the crucial role of homogeneous nucleation and inhibiting Ostwald ripening in stabilizing the halide perovskite from a thermodynamic mechanism perspective.