Barre 22-23, 3e étage, salle de conférences 317
Laurens D. A. Siebbeles – Chemical Engineering Department, Delft University of Technology, The Netherlands
Abstract
The dynamics of excitons, charge carriers and many-body complexes in CdSe nanoplatelets and 2D van der Waals materials were studied by ultrafast pump-probe optical and terahertz spectroscopy in combination with theory.
We found that the motion of excitons in CdSe nanoplatelets can be described by the quantum mechanical particle in-a-box model. Surprisingly, excitons appear to be stable even at high densities where they start to exhibit spatial overlap. We theoretically explain why a crossover to an electron-hole plasma does not occur.
According to experiments a single photon can excite two electrons in 2D MoTe2 and MoSe2 with much higher efficiency than in PbSe and PbS. We explain the disparate carrier multiplication efficiencies based on the band structure of the materials.
