Multifunctional Additives With Dual Anions and Alkali Metal Cation for Efficient Perovskite Light‐Emitting Diodes

Quasi‐2D perovskites have exhibited significant potential in perovskite light‐emitting diodes (PeLEDs) because of their advantages of high color purity and high photoluminescent quantum yield. Currently, the performance of green PeLEDs is primarily limited by low‐ n phases and defects in perovskite films, which result in low carrier mobility and non‐radiative recombination. Herein, we propose a tri‐functional additive strategy to obtain high‐quality perovskite films by incorporating biocompatible salicylates (sodium salicylate (NaSA) and potassium salicylate (KSA)) into quasi‐2D perovskite. This strategy demonstrates that the salicylate can passivate Pb defects through the coordination of C═O with unsaturated Pb 2+ ions and suppress the low‐ n phase formation via the interaction of the ─OH group with PEA + ions. Moreover, alkali metal ions (Na + or K + ) regulate the crystallization process and promote the radiative recombination. With such tri‐functionalization, the quasi‐2D pure green PeLEDs with NaSA as additive achieved a maximum external quantum efficiency (EQE) of 22.06% with emission peak at 527 nm and a maximum luminance of 36785 cd/m 2 . This work provides new insights into the role of multifunctional additives to enhance the electroluminescent performance of PeLEDs.