Time-dependent density-matrix functional theory for trion excitations: Application to monolayer MoS2 and other transition-metal dichalcogenides
Abbreviated Journal Title
SINGLE-LAYER MOS2; NEGATIVELY CHARGED EXCITONS; VALLEY POLARIZATION; ENERGY; TRANSISTORS; SYSTEMS; Physics, Condensed Matter
To examine optically excited bound states, excitons and trions, in monolayer MoS2, MoSe2, and WSe2, we have formulated and applied a generalized time-dependent density-matrix functional theory approach. Three different types of exchange-correlation (XC) kernels were used and their validity was evaluated through comparison with available experimental data. For excitons, we find that the local kernels, from the local density approximation and its gradient-corrected form, lead to much smaller binding energy than that extracted from experimental data, while those based on long-range (LR) interactions fare much better. The same is the case for the trion binding energy once screening effects are taken into account. Our results suggest that for both excitons and trions, the LR form of the XC kernel is necessary to describe bound states. These results confirm information from experimental data on single-layer dichalcogenides that their exciton and trion binding energies are of the order of hundreds (excitons) and tens (trions) of milli-electron volts, a result that may suggest technological application of these materials at room temperature. The proposed methodology can be straightforwardly extended to bound states with a larger number of electrons and holes than considered here.
A. Ramirez-Torres; V. Turkowski;T. S. Rahman
"Time-dependent density-matrix functional theory for trion excitations: Application to monolayer MoS2 and other transition-metal dichalcogenides" (2014). Faculty Bibliography 2010s. 5654.