While convenient solution-based procedures have been realized for the
synthesis of colloidal perovskite nanocrystals, the impact of surfactant ligands on the
shape, size, and surface properties still remains poorly understood, which calls for a
more detailed structure−morphology study. Herein we have systematically varied the
hydrocarbon chain composition of carboxylic acids and amines to investigate the
surface chemistry and the independent impact of acid and amine on the size and shape
of perovskite nanocrystals. Solution phase studies on purified nanocrystal samples by
1H NMR and IR spectroscopies have confirmed the presence of both carboxylate and
alkylammonium ligands on surfaces, with the alkylammonium ligand being much more
mobile and susceptible to detachment from the nanocrystal surfaces during polar
solvent washes. Moreover, the chain length variation of carboxylic acids and amines,
ranging from 18 carbons down to two carbons, has shown independent correlation to
the size and shape of nanocrystals in addition to the temperature effect. We have
additionally demonstrated that employing a more soluble cesium acetate precursor in place of the universally used Cs2CO3
results in enhanced processability without sacrificing optical properties, thus offering a more versatile recipe for perovskite
nanocrystal synthesis that allows the use of organic acids and amines bearing chains shorter than eight carbon atoms.
Overall our studies have shed light on the influence of ligand chemistry on crystal growth and stabilization of the
nanocrystals, which opens the door to functionalizable perovskite nanocrsytals through surface ligand manipulation.
Aizhao Pan,Bo He,Xiaoyun Fan,Zeke Liu,Jeffrey J.Urban,A.Paul Alivisatos,Ling He,and Yi Liu.