Quantifying the Thermodynamics of Ligand Binding to CsPbBr₃ Quantum Dots

Area of Science:

• Materials Science
• Nanotechnology
• Quantum Chemistry

Background:

• Cesium lead halide perovskites are promising quantum dots (QDs) with properties sensitive to surface chemistry.
• The thermodynamics of ligand binding on these QDs remain largely unstudied.

Purpose of the Study:

• To quantify the thermodynamics of ligand exchange on CsPbBr3 quantum dots.
• To understand how different ligands interact with the QD surface and affect their properties.

Main Methods:

• Utilized 1H NMR spectroscopy to measure ligand exchange thermodynamics.
• Investigated interactions of oleic acid, oleylamine, 10-undecenoic acid, 10-undecenylphosphonic acid, and undec-10-en-1-amine with CsPbBr3 QDs.

Main Results:

• Native ligands (oleic acid, oleylamine) exhibit dynamic interaction with surface densities of 1.2-1.7 nm⁻².
• 10-Undecenoic acid and undec-10-en-1-amine undergo exergonic ligand exchange with equilibrium constants (Keq) of 1.97 and 2.52, respectively.
• 10-Undecenylphosphonic acid shows irreversible ligand exchange; increased photoluminescence correlates with stronger binding ligands.

Conclusions:

• Ligand exchange occurs on CsPbBr3 QDs without nanocrystal etching.
• Understanding ligand binding thermodynamics is key to tuning QD properties for various applications.