The State Key Lab of
High Performance Ceramics and Superfine Microstructure
Shanghai Institute of Ceramics, Chinese Academy of Sciences
中 国 科 学 院 上 海 硅 酸 盐 研 究 所 高 性 能 陶 瓷 和 超 微 结 构 国 家 重 点 实 验 室
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Quantum Dots–Artificial Atoms, Large Molecules or Small Pieces of Bulk?
Insights from Time-Domain Ab Initio Studies.
Oleg Prezhdo
Department of Chemistry, University of Southern California
Senior Editor of the Journal of Physical Chemistry Letters
时间：2018年5月11日（星期五）9:30
地点：嘉定园区F区8层F8（2）会议室
欢迎广大科研人员和研究生参与讨论！
联系人：刘建军（52412801）
报告内容:
Quantum dots (QD) are quasi-zero dimensional structures with a unique combination of solid-state and atom-like properties. Unlike bulk or molecular materials, QD properties can be modified continuously by changing QD shape and size. Often, the bulk and molecular viewpoints contradict each other. The bulk view advocates that the kinetic energy of quantum confinement is greater than electron-hole interactions, that charge-phonon coupling is weak, and that the relaxation through quasi-continuous bands is rapid. The molecular view suggests strong electron-hole and charge-phonon interactions, and slow energy relaxation due to mismatch between electronic energy gaps and phonon frequencies. QDs exhibit new physical phenomena. The phonon bottleneck to electron energy relaxation and generation of multiple excitons can improve efficiencies of solar energy devices. The enhanced electron-hole interactions and high densities of states enable efficient Auger-type processes, which are impossible in both bulk and molecules. The observed QD properties are complicated by presence of ligands, dopants, defects and other atomistic features. We develop semiclassical and quantum-classical methods and implement them within time-dependent density functional theory to model far-from-equilibrium dynamics in QDs and other materials. The methods allow us to model QDs at the atomistic level and in time-domain, providing a unifying description of quantum dynamics on the nanoscale.
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主讲人简介:
Oleg V. Prezhdo obtained a Diploma in Theoretical Chemistry under Anatoly Luzano in 1991 from Kharkiv National University, Ukrainev and completed his Ph.D. under Peter Rossky at the University of Texas, Austin. After a postdoctoral fellowship with John Tully at Yale University, he joined the chemistry department at the University of Washington in 1998, achieving Associate and Full Professor in 2002 and 2005. In 2008, he was elected Fellow of the American Physical Society. In 2010, he was offered a Senior Professorship at the University of Rochester, and in 2014 at the University of Southern California. Since 2008, he has served as senior editor for the Journal of Physical Chemistry, since 2011 for the Journal of Physical Chemistry Letters, and as editor since 2013 for Surface Science Reports. Recipient of multiple national and international awards, he held invited professorships in France, Germany, Japan and China. His current research interests range from fundamental aspects of semiclassical physics, to excitation dynamics in nano-scale and biological systems.