Enhancing the efficiency of CsPbBr3 perovskite nanocrystal light‑emitting diodes through dodecyl ligand capping

Post-synthetic ligand exchange with dodecyl-based molecules, such as dodecanethiol (DDT) and didodecyldimethylammonium bromide (DDAB), has proven effective for enhancing the photophysical properties of CsPbX 3 nanocrystals (NCs). However, systematic evaluations of their performance in light-emitting diodes (LEDs) remain limited. In this study, we synthesized DDT- and DDAB-capped CsPbBr 3 NCs via ligand exchange from oleic acid/oleylamine (OA/OAm)-capped CsPbBr 3 NCs. LED device evaluation revealed that the DDT-capped CsPbBr 3 NC-based device achieved superior performance, with a peak external quantum efficiency of 18.02% and a maximum luminance of 4868 cd m −2 , outperforming devices based on DDAB- and OA/OAm-capped CsPbBr 3 NCs. Comprehensive Fourier-transform infrared spectroscopy analysis confirmed the complete replacement of OA/OAm by DDT ligands which induced substantial modifications in its surface characteristics and film formation. Notably, the preferential orientation of the DDT-capped CsPbBr 3 NC film along the (100) crystal plane was identified as a key factor for the enhanced LED performance. These findings underscore the crucial role of ligand-directed surface anisotropy in governing charge transport and electroluminescence in perovskite NCs, providing important theoretical guidance for developing high-efficiency perovskite LEDs.