Speaker: Dr. Siddhartha Sohoni
Department of Chemistry, University of Chicago
Title: “Creation of Non-annihilating electronic biexcitons at
room temperature”.
Day and Date: Tuesday, August 27, 2024
Time: 12.00 pm.
Venue: Room no. 350, Chemistry Department
Second floor, Annex
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Abstract When light interacts with matter, electronic excitations (excitons) form.
An exciton is a Coulombically bound electron-hole pair. In high fluence,
excitons can annihilate one another producing inefficient light harvesting
and reduced dynamic range for optoelectronics. In this talk, I will
describe our latest experiments that provide us with a post-synthetic
chemical strategy to block exciton-exciton annihilation. This strategy
allows us to switch reversibly between exciton annihilating and
non-annihilating phases of the material. In the non-annihilating phase, two
excitons reside on a single chromophore without interacting with each other
effectively forming a biexciton state. We observe that this biexciton state
remains stable throughout the excited-state lifetime of the chromophores.
In the talk, I will also describe the latest quantum mechanical theory that
explains the presence of these non-annihilating biexciton states.