Exciton diffusion in two-dimensional metal-halide perovskites

Two-dimensional perovskites, in which inorganic layers are stabilized by organic spacer molecules, are attracting increasing attention as a more robust analogue to the conventional three-dimensional metal-halide perovskites. However, reducing the perovskite dimensionality alters their optoelectronic...

Full description

Saved in:
Bibliographic Details
Published in:arXiv.org 2020-01
Main Authors: Seitz, Michael, Magdaleno, Alvaro J, Alcázar-Cano, Nerea, Meléndez, Marc, Lubbers, Tim J, Walraven, Sanne W, Pakdel, Sahar, Prada, Elsa, Delgado-Buscalioni, Rafael, Prins, Ferry
Format: Article
Language:English
Subjects:
Crystal structure
Crystallinity
Current carriers
Design optimization
Diffusion layers
Diffusion rate
Excitons
Fluorescence
Holes (electron deficiencies)
Metal halides
Optoelectronics
Perovskites
Single crystals
Transport properties
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Two-dimensional perovskites, in which inorganic layers are stabilized by organic spacer molecules, are attracting increasing attention as a more robust analogue to the conventional three-dimensional metal-halide perovskites. However, reducing the perovskite dimensionality alters their optoelectronic properties dramatically, yielding excited states that are dominated by bound electron-hole pairs known as excitons, rather than by free charge carriers common to their bulk counterparts. Despite the growing interest in two-dimensional perovskites for both light harvesting and light emitting applications, the full impact of the excitonic nature on their optoelectronic properties remains unclear, particularly regarding the spatial dynamics of the excitons within the two-dimensional (2D) plane. Here, we present direct measurements of in-plane exciton transport in single-crystalline layered perovskites. Using time-resolved fluorescence microscopy, we show that excitons undergo an initial fast, intrinsic normal diffusion through the crystalline plane, followed by a transition to a slower subdiffusive regime as excitons get trapped. Interestingly, the early intrinsic exciton diffusivity depends sensitively on the exact composition of the perovskite, such as the choice of organic spacer. We attribute these changes in exciton transport properties to strong exciton-phonon interactions and the formation of large exciton-polarons. Our findings provide a clear design strategy to optimize exciton transport in these systems.
ISSN:2331-8422
DOI:10.48550/arxiv.2001.05704