Custom‐Tailored Surface Morphology for Efficient Quasi‑2D Perovskite Light‑Emitting Diodes

Abstract Quasi‐2D perovskite light‐emitting diodes (Pero‐LEDs) are promising for next‐generation lightings and displays, yet their performance remains constrained by unbalanced carrier injection and non‐radiative recombination. In this study, a precise step‐wise antisolvent processing technique is presented to engineer custom‐tailored hillock‐shaped morphologies in quasi‐2D perovskite films. The controlled hillock‐shaped quasi‑2D perovskite films not only enhance electron injection efficiency by increasing the contact area between the emitting layer and electron transport layer, but also simultaneously improve crystallization quality and reduce defect density. As a result, the optimized devices achieve a maximum external quantum efficiency (EQE max ) of 26.25% and a threefold increase in luminance compared to control devices. This work provides a straightforward and scalable approach for morphology control, paving the way for high‐performance perovskite optoelectronic devices.