Stable Ligand Coordination at the Surface of Colloidal CsPbBr₃ Nanocrystals

Abstract

Ruling over the surface chemistry of metal halide perovskite nanocrystals (NCs) is crucial to access reliable luminophores. Here, we provide an atomic-level description of the surface of colloidal CsPbBr3 NCs, achieving an effective passivation strategy that leads to near-unity photoluminescence quantum yield. To this end, we used two different types of CsPbBr3 NCs, which had been synthesized with an outer shell of either oleylammonium bromide ion pairs or Cs-oleate complexes. We perturbed the dynamic equilibria at the NCs’ surface with ligands from a comprehensive library, including amines (and their conjugated acids) with different basicities, chain lengths, and steric encumbrances. We demonstrate that control of both ligand binding affinity and ligand-to-NC molar ratio is essential to attain thermodynamically stable coordination of the NC surface. We thus present a reliable protocol for managing the surface chemistry of colloidal CsPbBr3 NCs and for selectively addressing their ligand-induced morphological (and structural) transformations.

Transforming colloidal Cs4PbBr6 nanocrystals with poly(maleic anhydride-alt-1-octadecene) into stable CsPbBr3 perovskite emitters through intermediate heterostructures

“…S6-S9 †). In analogy with the widely studied oleylammonium/oleate-capped CsPbBr 3 NCs, 25,[34][35][36] the ligands on the surface of Cs 4 PbBr 6 NCs are likely to exist in a dynamic equilibrium between neutral and protonated species (oleylamine and oleylammonium, respectively). Thus neutral oleylamine is always available in the NC solution.…”

Stable Ultraconcentrated and Ultradilute Colloids of CsPbX3 (X = Cl, Br) Nanocrystals Using Natural Lecithin as a Capping Ligand

“…11 The surface chemistry of perovskite NCs has been shown to be vastly different from conventional semiconductor NCs, chiefly due to their ionic bonding and low lattice energy within the lead halide NC core (structural lability) and at the inorganic–organic interface. 12 Most specific challenges are the susceptibility of the NC cores to water and many other solvents due to their finite solubility and the loose binding of the surface-capping ligands. 13 These have been the major obstacles for studying, processing, and applications of perovskite NCs.…”

Synthesis of Red Cesium Lead Bromoiodide Nanocrystals Chelating Phenylated Phosphine Ligands with Enhanced Stability

“…The TPP and DPMP ligands possess bulky phenyl groups, which bring larger steric hindrance and moisture resistance compared with long-chain ligands, oleic acid (OA), and oleylamine (OAm). 37 After 3 days storage, the pristine and TPP (0.5 mg)-treated CsPbBrI 2 thin films changed from red to green under UV light irradiation, while the DPMP (0.5 mg)-treated CsPbBrI 2 thin films changed to orange. The phenomenon of color change from red to green suggests that those thin films were relatively unstable, possibly due to the composition alteration from CsPbBrI 2 to CsPbBr 3 .…”