Optimizing Interfaces Between Mixed‐Halide Perovskite Nanocrystals and Encapsulants Through Ligand Engineering for Stable White Light‐Emitting Diode Applications

ABSTRACT All inorganic mixed‐halide perovskite nanocrystals (PeNCs) have demonstrated great potential in display applications. However, poor stabilities of PeNCs under water, heat, and light strictly hinder their commercialization. Herein, by simultaneously employing a multifunctional ligand molecule, 8‐amino‐1‐naphthalenesulfonic acid (ANA), as well as SBA‐15 as the encapsulant, interactions at the interface of PeNCs/SBA‐15 were enhanced, which contributes to reduced defect density, suppressed recombination loss, and enhanced luminescence properties with a high photoluminescence quantum yield (PLQY) of over 90%. Moreover, target PeNCs exhibited much enhanced water, heat, and ultraviolet light stabilities compared to control samples. More importantly, white light‐emitting diode (WLED) devices based on these optimized PeNCs were fabricated, which demonstrated high color purity and a decent device half lifetime (T 50 ) of 320 h. This work highlights the significance of optimizing interfaces at PeNCs/encapsulant and is expected to promote future developments of stable PeNCs and LED devices.