Conjugated Alkylamine by Two-Step Surface Ligand Engineering in CsPbBr3 Perovskite Nanocrystals for Efficient Light-Emitting Diodes

Graphical Efficient green light-emitting diodes were fabricated by using CsPbBr 3 nanocrystals with excellent carrier transportation properties, owing to the introduction of conjugated alkyl-amine through two-step surface ligand engineering. LEDs exhibit a high luminance of 26,475 cd m −2 , a high CE of 23.53 cd A −1 by incorporation conjugation molecular ligand into the all-inorganic perovskite nanocrystals. Long alkyl-chain capped ligands are prerequisites for preserving high photoluminescence quantum yield (PLQY) in perovskite nanocrystals (NCs). Unfortunately, the insulating feature of surface ligands potentially hinders carrier transport in light-emitting diode (LED) devices, which will degenerate the LED performance. To overcome this shortcoming, we introduce a conjugated molecule, 3-phenyl-2-propen-1-amine (PPA), into CsPbBr 3 NCs through a two-step surface ligand engineering process. Owing to excellent electrical conductivity of PPA, PPA-capped CsPbBr 3 NCs LEDs exhibit a maximum current efficiency of 23.53 cd A −1 , and a maximum luminance of 26,475 cd m −2 at the wavelength of 517 nm. This work offers a new strategy to improve the quality of CsPbBr 3 NCs and LEDs by introducing conjugation molecular ligands into the all-inorganic perovskite nanocrystals.