Room Temperature Light-Mediated Long-Range Coupling of Excitons in Perovskites

TL;DR

This paper demonstrates tunable long-range coupling of excitons in perovskite quantum wells at room temperature, revealing indirect interactions and potential for exciton-polariton applications.

Contribution

It uncovers the mechanism of indirect, long-range exciton coupling in 2D perovskites and introduces a device design to enhance and tune these interactions.

Findings

Multiple exciton modes observed in reflection spectra.

Long-range, indirect exciton coupling demonstrated.

Device architecture with silver layer enhances excitonic modes.

Abstract

Perovskites have been the focus of attention due to their multitude of outstanding optoelectronic properties and structural versatility. Two-dimensional halide perovskite such as (C_6H_5C_2H_4NH_3)_2PbI_4, or simply PEPI, forms natural multiple quantum wells with enhanced light-matter interactions, making them attractive systems for further investigation. This work reports tunable splitting of exciton modes in PEPI resulting from strong light-matter interactions, manifested as multiple dips (modes) in the reflection spectra. While the origin of the redder mode is well understood, that for the bluer dip at room temperature is still lacking. Here, it is revealed that the presence of the multiple modes originates from an indirect coupling between excitons in different quantum wells. The long-range characteristic of the mediated coupling between excitons in distant quantum wells is also demonstrated in a structure design along with its tunability. Moreover, a device architecture involving an end silver layer enhances the two excitonic modes and provides further tunability. Importantly, this work will motivate the possibility of coupling of the excitonic modes with a confined light mode in a microcavity to produce multiple exciton-polariton modes.