  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.
