| AVS 62nd International Symposium & Exhibition | |
| 2D Materials Focus Topic | Tuesday Sessions |
| Session 2D+EM+NS+SS+TF-TuM |
| Session: | Optical and Optoelectronic Properties of 2D Materials |
| Presenter: | Volodymyr Turkowski, University of Central Florida |
| Authors: | V. Turkowski, University of Central Florida T.S. Rahman, University of Central Florida |
| Correspondent: | Click to Email |
We analyze the absorption spectrum and ultrafast charge dynamics in bi-layer 2L-MoS2 , 2L- MoSe2 and MoS2-WS2 systems by using time-dependent density functional theory in the density-matrix representation. In particular, we calculate the values of the binding energies of excitons in these structures for both intra- and inter-layer electron-hole excitations and demonstrate that, similar to the case of a single layer, these energies can be as large as hundred(s) of meVs. We also analyze the ultrafast dynamics of the electrons, holes and excitons in the photoexcited bilayers. We pay special attention to the ultrafast hole transfer in these systems and find transfer times of the order 100fs, in agreement with the experimental finding for the MoS2-WS2 system. We perform a detailed ab initio study of the spatially- and time-resolved charge density in the systems during the hole transfer and conclude that sulfur and selenium orbitals play an important role in the process. Finally, we discuss possible applications of the results in light harvesting technologies.
Work supported in part by DOE Grant No. DOE-DE-FG02-07ER46354