Ultrafast Formation of Charge Transfer Trions at Molecular-Doped 2D MoS2 Interfaces

In this work, we examined trion dynamics at an organometallic molecule/monolayer transition metal dichalcogenides (TMDs) heterojunction, using transient electronic sum frequency generation spectroscopy. Theoretical analysis showed that the ground state bleach and stimulated emission signal from transient electronic sum frequency generation cancel each other due to the opposite sign – different from that of transient absorption – which makes this technique specifically sensitive to trion formation dynamics. Upon pumping at 2.4eV, we observed an ultrafast hole transfer, followed by the formation of charge-transfer trions. The existence of charge-transfer trion exists at molecular functionalized TMDs heterojunction monolayer opens the possibility of engineering the local electronic structures and dynamics of specific locations on TMDs and offers the potential for transferring unique electronic attributes of TMD to the molecular layers for molecular-based spintronics.