MSE Colloquium, Sivan Refaely-Abramson

Sivan Refaely-Abramson

University of California at Berkeley

Post Doctoral Graduate

Faculty Host: Sahar Sharifzadeh

Student Host: Kirk Lewis

Refreshments at 2:45 PM

Complex Excited-State Phenomena from Predictive Computational Approaches

Abstract:

New developments in the theory of excited-state phenomena can lead to better understanding of light-matter interaction mechanisms in photophysics and predictions of new materials hosting such phenomena. In this talk, I will discuss recent studies using ab initio many-body perturbation theory to uncover and understand complex excited state mechanisms. I will present a new approach to calculate multi-exciton generation processes in solids from first principles, and describe an application of this approach to singlet fission in organic crystals. Focusing on crystalline pentacene, I will describe a new exciton- bi-exciton coupling channel, revealing a new selection rule for singlet fission associated with symmetry and structure in the solid state. Additionally, I will discuss a recent study of excited state properties in monolayer transition metal dichalcogenides with a dilute concentration of chalcogenide vacancies; these vacancies give rise to localized states, introduce strongly-bound excitons below the absorption edge, and reduce the valley-selective circular dichroism. These findings suggest a novel pathway to tune spin-valley polarization and other optical properties through defect engineering.

Bio:

Dr. Refaely-Abramson received a Bachelor's degree at the Hebrew University of Jerusalem in the Exact Sciences Combined Honors Program. She earned a Ph.D. degree at the Weizmann Institute of Science, with Prof. Leeor Kronig. Dr. Refaely-Abramson was a Postdoctoral Fellow with Prof. Jeffrey B. Neaton at University of California, Berkeley in the Molecular Foundry, Lawrence Berkeley National Laboratory. Her postdoctoral training is based in the Center for Computational Study of Excited-State Phenomena in Energy Materials (C2SEPEM), Berkeley Starting in October, 2018, Dr. Refaely-Abramson will begin a new position as a Senior Scientist at the Weizmann Institute of Science.

Dr. Refaely-Abramson received a Bachelor's degree at the Hebrew University of Jerusalem in the Exact Sciences Combined Honors Program. She earned a Ph.D. degree at the Weizmann Institute of Science, with Prof. Leeor Kronig. Dr. Refaely-Abramson was a Postdoctoral Fellow with Prof. Jeffrey B. Neaton at University of California, Berkeley in the Molecular Foundry, Lawrence Berkeley National Laboratory. Her postdoctoral training is based in the Center for Computational Study of Excited-State Phenomena in Energy Materials (C2SEPEM), Berkeley