Bilateral Embedded Anchoring via Tailored Polymer Brush for Large‐Area Air‐processed Blue Light‐Emitting Diodes

Abstract Perovskite light‐emitting diodes (PeLEDs) that can be air‐processed promises the development of displaying optoelectronic device, while is challenged by technical difficulty on both the active layer and hole transport layer (HTL) caused by the unavoidable humidity interference. Here, we propose and validate that, planting the polymer brush with tailored functional groups in inorganic HTL, provides unique bilateral embedded anchoring that is capable of simultaneously addressing the n phases crystallization rates in the active layer as well as the deteriorated particulate surface defects in HTL. Exemplified by zwitterionic polyethyleneimine‐sulfonate (PEIS) in present study, its implanting in NiO x HTL offers abundant nuclei sites of amino and sulfonate groups that balance the growth rate of different n phases in quasi‐2D perovskite films. Moreover, the PEIS effectively nailed the interfacial contact between perovskite and NiO x , and reduced the particulate surface defects in HTL, leading to the enhanced PLQY and stability of large‐area blue perovskite film in ambient air. By virtue of these merits, present work achieves the first demonstration of the air‐processed blue PeLEDs in large emitting area of 1.0 cm 2 with peak external quantum efficiency (EQE) of 2.09 %, which is comparable to the similar pure‐bromide blue PeLEDs fabricated in glovebox.