Ligand‐Exchange of Low‐Temperature Synthesized CsPbBr3 Perovskite toward High‐Efficiency Light‐Emitting Diodes. Issue 3 (7th January 2019) - Ye, Fanghao
Abstract: CsPbX3 perovskite nanocrystals (NCs) are promising light‐emitting materials that have gained significant attention over the past few years. The synthesis of CsPbX3 NCs is usually performed in an inert environment under high temperature conditions; however, this requirement hinders commercial development. Low‐temperature preparation of CsPbX3 NCs with rationally designed surface ligands is crucial to the performance and stability of CsPbX3 light‐emitting diodes (LEDs). In this work, short‐chain ligand‐anchored CsPbBr3 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 CsPbBr3 NCs LEDs. It is found that CsPbBr3 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. Abstract : Short‐chain ligand‐anchored CsPbBr3 nanocrystals (NCs) are synthesized in ambient conditions at room temperature using environmentally friendly solvents, and a ligand‐exchange process is performed to replace those short‐chain ligands with longer‐chain acid/amine ligand pairs, resulting in the dramatic improvement of performance and stability of CsPbBr3 NCs light‐emitting diodes.