Surface Stabilization of Colloidal Perovskite Nanocrystals via Multi-amine Chelating Ligands

Developing pathways to stabilize the intrinsically dynamic surface of metal halide perovskite nanocrystals (PNCs), especially metastable lead iodide PNCs, is an important but challenging task. Herein, we have realized ultra-stable colloidal CsPbI3 PNCs based on a multi-amine chelating ligand, N′-(2-aminoethyl)-N′-hexadecylethane-1,2-diamine (AHDA). The protonated AHDA can anchor the PNC surface lattice with a high binding energy of 2.36 eV, much larger than the 1.47 eV achieved with the commonly used oleylammonium ligands. The chelation effect greatly inhibits dynamic desorption of surface ligands and enables stabilization of CsPbI3 PNCs under various ambient stimuli, such as repeated purification (up to 15 cycles), polar solvents, heat, and light. The stable yet easily accessible surface of the AHDA-capped CsPbI3 PNCs renders them a robust photocatalyst in a stereoselective C–C oxidative coupling reaction. Furthermore, we show that the AHDA ligand can also be used to synthesize PNCs of several other compositions, namely CsPbCl3, CsPbBr3, CsPbBrI2, and hybrid FAPbI3 (FA = formamidine), with remarkably stable emission characteristics.