Impact of the Ligand Shell on Structural Changes and Decomposition of All-Inorganic Mixed-Halide Perovskite (CsPbX3) Nanocrystals under X-Ray Illumination

TL;DR

This study investigates how different surface ligands affect the structural stability and decomposition pathways of CsPbX3 nanocrystals under X-ray illumination, revealing ligand-dependent decay mechanisms and potential for improved scintillator applications.

Contribution

It demonstrates that ligand choice significantly influences the decomposition process and stability of CsPbX3 nanocrystals under X-ray exposure, introducing a new approach to enhance their durability.

Findings

Ligand type affects decomposition rate and pathway.

Metal porphyrin functionalization slows decay and alters decomposition.

Lattice contraction precedes nanocrystal decay under X-ray.

Abstract

We show that the decomposition of caesium lead halide perovskite nanocrystals under continuous X-ray illumination depends on the surface ligand. For oleic acid/oleylamine, we observe a fast decay accompanied by the formation of elemental lead and halogen. Upon surface functionalization with a metal porphyrin derivate, the decay is markedly slower and involves the disproportionation of lead to Pb0 and Pb3+. In both cases, the decomposition is preceded by a contraction of the atomic lattice, which appears to initiate the decay. We find that the metal porphyrin derivative induces a strong surface dipole on the nanocrystals, which we hold responsible for the altered and slower decomposition pathway. These results are important for application of lead halide perovskite nanocrystals in X-ray scintillators.