EP02.10.01 : The Importance of Structural Dynamics on Electronic and Optical Properties of Nanomaterials

8:00 AM–8:30 AM Apr 5, 2018 (America - Denver)

PCC North, 200 Level, Room 222 BC

Vanessa Wood1

1, ETH Zürich, Zürich, , Switzerland

This talk will describe why structural dynamics are important and provide ideas on how to control structural dynamics in nanocrystals (NCs). I will begin by describing the type of structural dynamics that occurs in NCs and the methods that we can use to measure structural dynamics, such as inelastic neutron scattering and inelastic x-ray scattering, or simulate it, such as ab initio molecular dynamics. Then I will describe the theory of how electrons and vibrations interact, and the challenges we face in calculating non-radiative electronic transitions rates. Finally, I will explain why we should care about structure dynamics, specifically the impact the type of dynamics has on optical properties such as carrier cooling, homogenous linewidths, thermal broadening, and electronic properties such as mobility and Shockley Read Hall non-radiative recombination.
In my talk, I will rely on the example of NCs, where structural dynamics can explain for example the large thermal broadening and fast carrier cooling rates experimentally observed in Pb-chalcogenide NCs. Furthermore, changing the structural dynamics (e.g., by changing the surface of NCs) can reduce the thermal broadening and slow carrier cooling due to reduction of both the thermal displacement of surface atoms and the spatial overlap of the charge carriers with these large atomic vibrations. However, it is important to remember that these phenomena are relevant not only for NC, but also for bulk semiconductors and small molecules.