Observation of Transient Trion Induced by Ultrafast Charge Transfer in Graphene/MoS2 Heterostructure

TL;DR

This study demonstrates an indirect optical method to generate and control transient trions in graphene/MoS2 heterostructures via ultrafast charge transfer, revealing longer lifetimes and new quasiparticle dynamics.

Contribution

It introduces a novel approach for transient trion generation through ultrafast charge transfer, enabling dynamic control in 2D heterostructures.

Findings

Transient trions have longer lifetimes than excitons.

Charge transfer controls the trion-to-exciton ratio.

Ultrafast charge transfer enables dynamic quasiparticle manipulation.

Abstract

Van der Waals (Vdw) heterostructures constructed from TMDCs provide an ideal platform for exploring various quasiparticle behaviors, with trion-composed of neutral exciton and charged carrier-being a notable example. There are typically three methods to generate trion: electrical doping, chemical doping, and direct optical doping. The first two methods generate static trion, while the last gives rise to transient trion. Here, we present an indirect optical doping approach to generate transient trion via ultrafast charge transfer (CT) and achieve control over the trion-to-exciton ratio by adjusting CT in Gr/MoS2 heterostructure. Furthermore, we demonstrated that dynamics of the transient trion generated with this method, which shows slightly longer lifetime than that of exciton accounted for the Coulomb interactions between trion and charged defect. This study provides fresh perspectives on the construction of new quasiparticles, dynamical characterization and the control of the many-body interaction in two-dimensional structure.