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 Pb2+ 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/m2. This work provides new insights into the role of multifunctional additives to enhance the electroluminescent performance of PeLEDs.