[MOS] 5/3 - Modern Optics and Spectroscopy Virtual Seminar with Aaron Lindenberg (Stanford)

[Christine Brooks]

There will be a virtual Modern Optics and Spectroscopy Seminar held next Tuesday, May 3 at 12pm. A short Q&A segment will immediately follow the conclusion of the seminar.

Zoom link: https://mit.zoom.us/j/98076834433?pwd=eTRIR2xOdDdHTFF0SmErcHFEclVyZz09
Password: 836631
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Aaron M. Lindenberg
Stanford University

“Exciton-driven dynamic symmetry changes and concerted lattice distortions in perovskite quantum dots”

A central problem in condensed matter physics is to understand the fundamental coupling mechanisms between electrons and ions and the emergent phenomena that arise from these microscopic interactions.  In this talk I will describe recent femtosecond-resolved electron scattering experiments probing the dynamic microscopic interactions between excitons and the lattice in a class of lead-halide hybrid perovskite quantum dots.   Understanding the origins of electron-phonon coupling in these materials is key to interpreting and leveraging their unique optoelectronic properties.  I will show how our measurements enable direct visualization and quantification of exciton-lattice coupling, leading to an ultrafast increase in symmetry through reduction in octahedral tilts.  We further demonstrate that the symmetry enhancing reorganizations induced by each exciton in a multi-excitonic state constructively interfere, giving rise to a coupling strength which scales quadratically with exciton number. This super-linear scaling induces phonon-mediated attractive interactions between excitons in lead halide perovskites and opens up new opportunities for controlling dynamic disorder in polymorphic structures.

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Christine Brooks
Administrative Assistant
Massachusetts Institute of Technology
Department of Chemistry
77 Massachusetts Ave, 6-333
Cambridge, MA 02139
p: 617.253.7239
e: cbrooks at mit.edu<mailto:cbrooks at mit.edu>

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