IBS CMSD Seminar_Prof. Dong Hee Son (Texas A&M University)(Sep. 28, 2022)
IBS Center for Molecular Spectroscopy and Dynamics
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n SPEAKER
Prof. Dong Hee Son (Texas A&M University)
n TITLE
Excitons
and hot electrons in strongly quantum confined perovskite nanostructures
n ABSTRACT
Perovskite
quantum dots (QDs) are emerging as an excellent source of photons and charge
carriers for photonic and photovoltaic applications that are superior to many
existing semiconductor quantum dots. In this presentation, I will discuss the
energetics and relaxation dynamics of bright and dark excitons in strongly
quantum confined cesium lead halide perovskite QDs that dictate various
photophysical properties in this new family of QDs. For this purpose, we
prepared the QDs with varying degree of confinement in non-interacting ensemble
and electronically coupled arrays of QDs as well as in the magnetically doped
non-interacting QDs. The effect of confinement-enhanced electron-hole exchange
interaction in strongly confined QDs on bright-dark level splitting and the
rates of bright and dark exciton emission were studied via time-resolved
photoluminescence (PL) of exciton in the non-interacting ensemble. The effect
of electronic coupling in the 2-dimensional QD arrays altering the
electron-hole exchange interaction and the exciton fine structure was studied
via the time-resolved exciton PL obtained at cryogenic temperatures. In
addition, doping of strongly confined perovskite nanocrystals open a
photophysical pathway that that enables the generation of energetic hot
electron via exciton-to-hot electron upconversion under weak cw excitation,
which enables the photoemission of hot electrons above the vacuum level. The
implication of these hot electrons for photocatalysis will also be discussed.
n DATE AND VENUE
September 28, 2022 (Wednesday, 17:00 - 18:00)
Seminar Room A (116)
n LANGUAGE
English
n INVITED BY
Prof. Kyungwon Kwak