Induced Chirality in Halide Perovskite Clusters through Surface Chemistry.

Area of Science:

• Materials Science
• Quantum Chemistry
• Nanotechnology

Background:

• Chiroptical properties are crucial for applications like spintronics and polarized photodetectors.
• Introducing chiroptical activity into semiconductors is difficult due to challenges in creating asymmetric crystal structures.
• Chirality transfer using chiral organic molecules as capping ligands on nanocrystals is a promising approach.

Purpose of the Study:

• To explore the mechanisms of chirality transfer in semiconductor nanocrystals capped with chiral ligands.
• To investigate the role of chiral diaminocyclohexane (DACH) enantiomers in inducing chiroptical activity in CsPbX3 clusters.
• To provide mechanistic insights for enhancing chiroptical functionality in nanomaterials.

Main Methods:

• Atomistic modeling using time-dependent density functional theory (TD-DFT) calculations.
• Simulation of chirality transfer in cesium lead halide (CsPbX3) clusters capped with DACH enantiomers.
• Analysis of optical transitions and coupling mechanisms.

Main Results:

• DACH enantiomers bound to CsPbX3 cluster surfaces induce chiral signatures in the perovskite's optical transitions.
• Chirality transfer is effectively rationalized by chiral molecular dipole-cluster transition dipole coupling.
• Anisotropy factors increase proportionally with surface ligand density, indicating a route to enhance chiroptical effects.

Conclusions:

• Chirality transfer from DACH ligands to CsPbX3 clusters is demonstrated via atomistic modeling.
• The chiral dipole-cluster coupling mechanism explains the observed emergent chiroptical activity.
• Surface ligand density is a key factor for optimizing chiroptical functionality in semiconductor nanomaterials.