Exciton Radiative Recombination Dynamics and Nonradiative Energy Transfer in Two-Dimensional Transition-Metal Dichalcogenides
2019
Liu, Huan | Wang, Ting | Wang, Chong | Liu, Dameng | Luo, Jianbin
We employ fluorescence lifetime imaging technology to explore exciton radiative recombination dynamics in layered transition-metal dichalcogenides (TMDCs) and nonradiative energy transfer from CdSe/ZnS quantum dot (QD) to monolayer TMDCs (MoS₂, WS₂, and WSe₂). Owing to an indirect–direct band gap transition, exciton radiative lifetimes decrease with the TMDCs’ layer number reducing. The fastest exciton recombination rate is observed in monolayer TMDCs, which is attributed to their reduced dielectric screening. Furthermore, the effect of reduced dielectric screening on nonradiative energy transfer from QDs to monolayer TMDCs is investigated. The fastest energy transfer rate is observed in QD/WS₂ heterostructure owing to weak dielectric screening of monolayer WS₂, and the slowest rate in QDs/MoS₂ is caused by strong dielectric screening of monolayer MoS₂. Our experiments provide fundamental insights into exciton recombination dynamics in TMDCs and potentially enable new avenues for controlling motion of excitonic energy conversion on a nanoscale.
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