Abstract
Two-dimensional (2D) semiconductors bear great promise for application in optoelectronic devices, but the low diffusivity of excitons stands as a notable challenge for device development. Here, we demonstrate that the diffusivity of excitons in monolayer MoS2 can be improved from 1.5 ± 0.5 to 22.5 ± 2.5 square centimeters per second with the presence of trapped charges. This is manifested by a spatial expansion of photoluminescence when the incident power reaches a threshold value to enable the onset of exciton Mott transition. The trapped charges are estimated to be in a scale of 1010 per square centimeter and do not affect the emission features and recombination dynamics of the excitons. The result indicates that trapped charges provide an attractive strategy to screen exciton scattering with phonons and impurities/defects. Pointing towards a new pathway to control exciton transport and many-body interactions in 2D semiconductors.
| Original language | English |
|---|---|
| Article number | eabb4823 |
| Journal | Science Advances |
| Volume | 6 |
| Issue number | 51 |
| DOIs | |
| State | Published - Dec 2020 |
Funding
at North Carolina State University, which is supported by the State of North Carolina and the NSF. Part of the Raman and PL measurements was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. We also acknowledge C. Xu and K. Gundogdu for help with the pump-probe measurement. Funding: This work was supported by the NSF under a grant of EFMA 1741693 and DMR 1709934. Author contributions: Yiling Yu and L.C. conceived the idea. Yiling Yu performed the measurement. Yiling Yu and L.C. designed the experiments, analyzed the data, and wrote the manuscript. Yifei Yu and G.L. helped with the synthesis and transfer of the samples. D.B.G. and A.A.P. performed some of PL and Raman measurements and assisted in writing the manuscript. All the authors were involved in reviewing the manuscript. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors.