Ligand Field Exciton Annihilation in Bulk CrCl3

TL;DR

This study investigates ligand field excitons in bulk CrCl3, revealing their strong binding, long lifetimes, and exciton-exciton annihilation dynamics, which are relevant for optoelectronic and magnetic properties.

Contribution

It provides the first experimental quantification of exciton annihilation rates in CrCl3 and links these dynamics to a universal scaling theory.

Findings

Exciton relaxation is dominated by exciton-exciton annihilation.

The spontaneous decay lifetime of excitons is very long.

Quantified exciton annihilation rate constant and related it to universal scaling behavior.

Abstract

The layered van der Waals material CrCl3 exhibits very strongly bound ligand field excitons that control optoelectronic applications and are connected with magnetic ordering by virtue of their d-orbital origin. Time-resolved photoluminescence of these exciton populations at room temperature shows that their relaxation is dominated by exciton-exciton annihilation and that the spontaneous decay lifetime is very long. These observations allow the rough quantification of the exciton annihilation rate constant and contextualization in light of a recent theory of universal scaling behavior of the annihilation process.