Charge Carrier Dynamics
It is challenging to characterize charge carrier movement in semiconductor nanostructures, partly because of the complications of attaching contacts to the sample. Moreover, conductivity measurements at low frequencies are inherently limited in the information content. These drawbacks can be circumvented using freely propagating THz pulses. The rapidly varying electric field contained in these pulses with durations of ~1 picosecond allows for the investigation of key electronic properties of materials such as the electron mean-free path, exciton properties and confinement effects in nanostructured materials. Furthermore, the high time resolution of this technique allows the study of dynamic processes and/or systems far from equilibrium using a pump-probe experimental approach. Using THz spectroscopy, we investigate charge dynamics in building blocks for solar cells: graphene-based materials, conjugated polymers, nanostructured semi-conductors.
In particular , concerning "charge carrier dynamics", the department is interested in the following topics:
- single-molecule charging / charge transfer behavior (Domke, Wang)
- conjugated polymers for transistors (Baumgarten)
- conjugated polymers for photoconductivity and thz spectroscopy (Baumgarten, Wang)
- many body effect (e.g. exciton) in low dimensional materials (Kim, Ulbricht, Wang)
- carrier dynamics in 2D Van der Waals structures (Kim, Ulbricht, Wang)
- ionic dynamics at graphene/electrolyte interfaces (Wang)
- solid-state defects (Kim, Ulbricht)
- optical dynamics over multiple timescales (Ulbricht)
- interplay between charge and lattice dynamics (Kim, Ulbricht)
Together with other MPI-P groups, we are researching the central research topics "Defect Engineering", "Non-equilibrium structure formation" and "Multiscale challenges"