Event Details
On the nature of exciton-bath interactions in two-dimensional lead halide perovskites
Presenter: Ajay Srimath Kandada
Supervisor:
Date: Wed, February 13, 2019
Time: 14:30:00 - 15:30:00
Place: ELL 230
ABSTRACT
Excitonic interactions in 2D semiconductors garner considerable attention, both due to their relevance in quantum opto-electronics and to the richness of their physics. Quantum-well like derivatives of organic-inorganic perovskites are emerging material systems where strongly bound two-dimensional excitons have been observed even at room temperature.1 These hybrid semiconductors feature complex lattice dynamics due to the ‘softness’ arising from non-covalent bonds between molecular moieties and the inorganic network and due to the ionic character of the crystal.2 I will discuss the profound and unique consequences of such dynamic structural complexity on the fundamental character of primary photo-excitations. I will present evidences of polaronic effects3 and multi-body correlations,2 both of which are strongly affected by the lattice dynamics, based on various ultrafast optical spectroscopies.
(1) Neutzner, S.; Thouin, F.; Cortecchia, D.; Petrozza, A.; Silva, C.; Kandada, A. R. S. Exciton-Polaron Spectral Structures in Two Dimensional Hybrid Lead-Halide Perovskites. Phys. Rev. Mater. 2018, 2, 064605.
(2) Thouin, F.; Neutzner, S.; Cortecchia, D.; Dragomir, V. A.; Soci, C.; Salim, T.; Lam, Y. M.; Leonelli, R.; Petrozza, A.; Kandada, A. R. S.; et al. Stable Biexcitons in Two-Dimensional Metal-Halide Perovskites with Strong Dynamic Lattice Disorder. Phys. Rev. Mater. 2018, 2, 034001.
(3) Thouin, F.; Chávez, D. A. V.; Quarti, C.; Cortecchia, D.; Bargigia, I.; Beljonne, D.; Petrozza, A.; Silva, C.; Kandada, A. R. S. Phonon Coherences Reveal the Polaronic Character of Excitons in Two-Dimensional Lead-Halide Perovskites. Nat. Mater. 2019, DOI: 10.1038/s41563-018-0262-7.