Charged and neutral excitons in colloidal nanoplatelets

• Applicant: Dr. Elena Shornikova, Ph.D.
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 462009643

A novel class of colloidal nanocrystals, in particular two-dimensional nanoplatelets, with extended lateral dimensions and atomically controlled thickness of a few monolayers only will be investigated. Excitons and exciton complexes in nanoplatelets undergo strong spatial confinement, because nanoplatelet thickness is typically about 1 nm, and strong dielectric enhancement due to the significantly smaller dielectric constant of the environment compared to the nanoplatelet material. CdSe, CdS, and CdTe nanoplatelets, as well as core/shell and core/crown structures, will be studied by different kinds of optical and magneto-optical techniques at cryogenic and room temperatures. The measurements will be performed on ensembles of oriented and randomly distributed nanoplatelets, as well as on single nanoplatelets. Basic exciton parameters, such as exciton and trion binding energies, exciton fine structure splitting, and energy level structure of excited exciton states will be evaluated. Exciton interaction with the surface spins and the role of these spins in the dark exciton recombination mechanism will be investigated. For this, nanoplatelets with various surface treatment will be prepared. An optical method of studying spin and charge properties of the surface of colloidal nanoplatelets by means of exciton spectroscopy will be developed.

• DFG Programme: Research Grants