Exciton Delocalization in Amino-Functionalized Inorganic MoS2 Quantum Disks: Giant Davydov Splitting and Exchange Narrowing

Abstract

Exciton delocalization, a phenomenon in which spatial extension of the excitons spreads over aggregates, has attracted significant attention in both academia and industry. Studies on exciton delocalization focus mainly on dye molecules and organic conjugated solids because of their high binding energies. Here, we report on exciton delocalization from inorganic ${\mathrm{Mo}\mathrm{S}}_{2}$ quantum disks (QDs) functionalized with diethylenetriamine (DETA). By increasing the QD concentration, a giant Davydov splitting with an energy of up to 850 meV and an exchange narrowing with an exciton delocalization length up to several tens of QDs are observed. Notably, exciton delocalization in amino-functionalized ${\mathrm{Mo}\mathrm{S}}_{2}$ QDs can be controlled by the DETA concentration. Amino-related bonding is suggested to modulate the Davydov splitting. Understanding the mechanism of exciton delocalization in two-dimensional QDs is expected to be useful and open up a route for the discovery of unique physical phenomena and the development of as-yet unrealized devices.