Ligand‐Exchange of Low‐Temperature Synthesized CsPbBr₃ Perovskite toward High‐Efficiency Light‐Emitting Diodes

CsPbX 3 perovskite nanocrystals (NCs) are promising light‐emitting materials that have gained significant attention over the past few years. The synthesis of CsPbX 3 NCs is usually performed in an inert environment under high temperature conditions; however, this requirement hinders commercial development. Low‐temperature preparation of CsPbX 3 NCs with rationally designed surface ligands is crucial to the performance and stability of CsPbX 3 light‐emitting diodes (LEDs). In this work, short‐chain ligand‐anchored CsPbBr 3 NCs in ambient conditions at room temperature are synthesized and a ligand‐exchange strategy is employed, using longer‐chain acid/amine ligand pairs, resulting in the dramatic improvement of performance and stability of CsPbBr 3 NCs LEDs. It is found that CsPbBr 3 NCs anchored by oleic acid and oleylamine complex ligands result in the best LED performance, with the maximum luminance of 5033 Cd m −2 , current efficiency of 18.6 Cd A −1 , external quantum efficiency of 5.4%, turn‐on voltage of 3.2 V, and the best thermal stability under ambient conditions.