Exciton diffusion in two-dimensional metal-halide perovskites.

Area of Science:

• Materials Science
• Optoelectronics
• Solid-State Physics

Background:

• Two-dimensional (2D) layered perovskites offer enhanced stability over 3D analogues for light harvesting and emission.
• The influence of reduced dimensionality on exciton dynamics in 2D perovskites requires further investigation.

Purpose of the Study:

• To directly measure exciton transport dynamics within the 2D plane of single-crystalline layered perovskites.
• To elucidate the factors governing exciton spatial diffusion and their relationship with material properties.

Main Methods:

• Transient photoluminescence microscopy was employed to track exciton movement.
• Measurements were performed on single-crystalline layered perovskite samples.

Main Results:

• Excitons exhibit initial fast in-plane diffusion, transitioning to a slower subdiffusive regime due to trapping.
• Exciton diffusivity is sensitive to the organic spacer composition.
• A correlation between lattice stiffness and exciton diffusivity was observed, indicating dominant exciton-phonon interactions.

Conclusions:

• Exciton transport in 2D layered perovskites is governed by exciton-phonon interactions and exciton-polaron formation.
• The choice of organic spacer significantly impacts exciton dynamics.
• Findings offer a design strategy for optimizing exciton transport in perovskite materials for optoelectronic devices.