Probing charge transfer excitons in a MoSe2-WS2 van der Waals heterostructure
Frank Ceballos1, Matthew Z Bellus, Hsin-Ying Chiu
1Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045, USA. huizhao@ku.edu.
Abstract:
We show that the van der Waals heterostructure formed by MoSe2 and WS2 provides a unique system with near degenerate interlayer and intralayer excitonic states. Photoluminescence measurements indicate that the charge transfer exciton states are approximately 50 meV below the MoSe2 exciton states, with a significant spectral overlap. The transient absorption of a femtosecond pulse was used to study the dynamics of the charge transfer excitons at room temperature. We found a lifetime of approximately 80 ps for the charge transfer excitons. A diffusion coefficient of about 14 cm(2) s(-1) was deduced, which is comparable to individual excitons in transition metal dichalcogenides.
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