Lauréat 2022 du prix de thèse 2021 du GDR NAME
Prize #1 for Nikita
KAVOKINE (ENS, Paris)
Many-body effects in nanoscale fluid
transport
(nkavokine@flatironinstitute.org)
The transport of confined fluids at the nanometric scale
is the fundamental ingredient of many complex
processes, ranging from the desalination of seawater to
neurotransmission. While the experimental systems for
the study of these transport phenomena today reach
molecular sizes, the models used to describe them are
best formulated in a mesoscopic framework. This thesis
develops new theoretical tools, specific to nanoscale
fluids, which shed light on unexpected phenomena in
extreme confinement. We first show, by non-equilibrium
statistical physics methods, that ion correlations in
confined electrolytes result in nonlinear transport
phenomena, ranging from ionic Coulomb blockade to
memory effects and neuromorphic behaviors. We then
show, using field theory tools, the emergence of
quantum effects at the solid-liquid interface, through a
contribution of electronic excitations to hydrodynamic
friction. These results suggest the possibility of
controlling nanofluidic transport by the electronic
properties of the confining walls, and establish a link
between liquid physics and condensed matter physics.
The thesis also includes an experimental part, which
presents the study of the instability of a suspension of
nanoparticles, as well as the development of a device
for measuring water flow in two-dimensional channels.
Prize #2 for Lipin CHEN
(INSTITUT FOTON, Rennes)
Optoelectronic, vibrational and transport
properties of III-V/Si antiphase boundaries for
photonics and solar energy harvesting
(lipin.chen@universite-paris-saclay.fr)
In this thesis, we investigate the specific optoelectronic
properties of III-V/Si Anti-Phase Boundaries (APBs) and
its use for energy harvesting devices theoretically and
experimentally. Strong electron-phonon coupling around
stoichiometric APBs are first demonstrated due to
simultaneous confinement of charge carriers and
phonons in the same region, based on structural and
optical characterizations and density functional theory
calculations. The GaPSb/Si tandem materials
association for solar water splitting is then studied.
Combining ellipsometry measurements and tight
binding calculations, the bandgap of GaPSb alloys in the
whole Sb range and band lineups of GaPSb/Si with
water redox levels are obtained, which shows the
potential of the GaPSb/Si association for the hydrogen
evolution and oxygen evolution reactions. Then a
GaP0.67Sb0.33/Si photoanode with an almost optimal
bandgap combination (1.7eV/1.1eV) was investigated
for photoelectrochemical (PEC) water splitting with
promising performances related to efficient sunlight
spectrum absorption. Finally, the transport and PEC
properties of III-V/Si with vertical non-stoichiometric
APBs are investigated by experimental characterizations
and first-principle calculations. We demonstrate that
epitaxial III-V/Si materials with vertical non-
stoichiometric APBs are hybrid structures, composed of
bulk photo-active semiconductors with 2D topological
semi metallic vertical inclusions, enabling
simultaneously good photo-activity, efficient charge
transport and separation, and interesting ambipolar
properties.
GDR Nanomaterials for Energy Applications 