Seminarium Fizyki Ciała Stałego

Optical properties of low-dimensional semiconductor nanostructures are often driven by excitons – a quasi-particle composed of a photo-created electron and hole bound by the Coulomb attraction. Excitonic effects are particularly strong in two-dimensional (2D) van der Waals semiconductors, in which simultaneous quantum and dielectric confinement enhance the binding energy of the electron-hole pair to values as large as hundreds of meV. A prominent example is the 2D Ruddlesden–Popper metal-halide perovskites (2DP), in which exciton binding energies reach a few hundred milli-electronvolts. Additionally, the soft, polar, and low symmetry lattice creates a unique background for electron-hole interaction in 2DP, providing a fascinating playground for studying the exciton physics which in some aspects remain challenging for our understanding our understanding.Here I will discuss certain aspects of excitonic physics in 2D perovskites related to their energy structure, and unique behaviours (probably) resulting from the particularly strong coupling of electronic excitation with lattice vibration. This aspect includes a variation of exciton binding energy with temperature and the possibility to observe exciton fine structure splitting of phonon replica. I will also show that the van der Waals nature of 2DP allows to easily combine them with other 2D materials, in particular transition metal dichalcogenide. The nontrivial band alignment of such a stack provides conditions for the charge transfer, resulting in the formation of interlayer excitons. Simultaneously strong excitonic effects in both types of materials facilitate energy transfer between the layers that can be tuned by an appropriate alignment of the excitonic states.UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)