Chinese Physics Letters,
Год журнала:
2023,
Номер
40(6), С. 067801 - 067801
Опубликована: Май 1, 2023
Optical
fine-tunable
layer-hybridized
Moiré
excitons
are
highly
in
demand
for
emerging
many-body
states
two-dimensional
semiconductors.
We
report
naturally
confined
bright
with
long
lifetimes
twisted
hexagonal
GaTe
bilayers,
using
ab
initio
perturbation
theory
and
the
Bethe–Salpeter
equation.
Due
to
hybridization
of
electrons
holes
between
layers,
which
enhances
brightness
excitons,
bilayer
system
becomes
attractive
optical
applications.
find
that
both
R
H-type
stacking
superlattices,
more
than
200
meV
lateral
quantum
confinements
occur
on
exciton
energies,
results
two
scenarios:
(1)
The
ground
state
X
A
found
be
trapped
at
high-symmetry
points,
opposite
electric
dipoles
R-stacking
supercell,
forming
a
honeycomb
superlattice
nearest-neighbor
dipolar
attraction.
(2)
For
H-stacking
case,
is
only
one
point
exhibiting
triangular
superlattice.
Our
suggest
h-GaTe
promising
systems
excitonic
devices
provide
an
ideal
platform
realizing
strong
correlated
Bose–Hubbard
physics.
The Journal of Physical Chemistry Letters,
Год журнала:
2022,
Номер
13(50), С. 11760 - 11769
Опубликована: Дек. 14, 2022
In
this
Perspective,
we
introduce
a
first-principles
method
that
combines
time-dependent
density
functional
theory
with
non-adiabatic
molecular
dynamics
(NAMD)
to
explore
exciton
in
two-dimensional
(2D)
van
der
Waals
(vdW)
heterostructures.
The
theoretical
foundation
and
computational
efficiency
of
the
are
discussed
compared
those
related
methods
(e.g.,
GW-BSE).
Using
three
2D
vdW
heterostructures
as
examples,
demonstrate
proposed
can
provide
reliable
description
many-body
electron–hole
interactions
crucial
dynamics.
With
much
lower
costs
than
GW-BSE
method,
represents
particularly
promising
tool
probe
solids.
Moreover,
find
NAMD
simulations
widely
used
literature
cannot
capture
excitonic
effect
materials
often
yield
incorrect
results
because
they
formulated
single-particle
picture.
instances
where
picture
fails
pointed
out
contrasted
simulation
results.
Heterostructures
are
not
expected
to
form
in
a
single
homogeneous
material.
Here,
we
show
that
planar
pseudo-heterostructures
could
emerge
twisted
bilayer
of
phosphorene
(tbP),
driving
in-plane
energy
and
charge
transfer.
The
formation
moiré
superlattices
combined
with
electronic
anisotropy
tbPs
yields
one-dimensional
(1D)
excitons
long
radiative
nonradiative
lifetimes,
large
binding
energies,
deep
potentials.
Low-frequency
phonons
dynamic
potentials
revealed
be
responsible
for
the
energy/charge
transfer
exciton
dynamics.
1D
predicted
exhibit
Bose-Einstein
condensation
at
high
temperatures
may
lead
exotic
Tonks-Girardeau
Bose
gases.
Nature Communications,
Год журнала:
2024,
Номер
15(1)
Опубликована: Апрель 17, 2024
Abstract
Moiré
superlattices
of
transition
metal
dichalcogenides
offer
a
unique
platform
to
explore
correlated
exciton
physics
with
optical
spectroscopy.
Whereas
the
spatially
modulated
potentials
evoke
that
resonances
are
distinct
depending
on
site
in
moiré
supercell,
there
have
been
no
clear
demonstration
how
excitons
trapped
different
sites
dynamically
interact
doped
carriers;
so
far
exciton-electron
dynamic
interactions
were
presumed
be
site-dependent.
Thus,
transient
emergence
nonequilibrium
correlations
open
questions,
but
existing
studies
limited
steady-state
measurements.
Here
we
report
experimental
fingerprints
site-dependent
under
continuous-wave
as
well
ultrashort
excitations.
In
near-zero
angle-aligned
WSe
2
/WS
heterobilayers,
observe
intriguing
polarization
switching
and
strongly
enhanced
Pauli
blocking
near
Mott
insulating
state,
dictating
dominant
correlation-driven
effects.
When
twist
angle
is
60°,
such
observed,
suggesting
strong
dependence
atomic
registry
supercell
configuration.
Our
door
largely
unexplored
superlattices.
Interlayer
excitons
(IXs)
in
layered
van
der
Waals
materials
are
promising
for
quantum
technologies
and
fundamental
studies
such
as
exciton-polariton
condensation
due
to
their
large
permanent
dipole
moments.
However,
indirect
bandgap
optical
transition
through
the
Q-K
channel
renders
them
momentum
forbidden
thus
less
relevant
applications.
Here,
we
demonstrate
a
method
brightening
transitions
from
IX
emitters
(QEs)
2H-stacked
bilayer
WSe2
by
simultaneously
employing
local
strain
plasmonic
nanocavity
coupling.
Initially,
long
T1
lifetimes
up
140
ns
indicative
of
transitions.
Magneto-photoluminescence
data
show
striking
bimodal
distribution
g-factors
between
mono-
QEs,
with
well-defined
value
g
=
9.5
IX,
highlighting
nature
decoupling
variations.
In
addition,
angle-resolved
PL
measurements
reveal
that
curvature
on
nanostressor
induces
orientation
tilt
affecting
cavity
By
embedding
these
strained
QEs
into
cavities,
achieve
10-fold
increase
emission
intensity
24-fold
enhancement
lifetime
best
case
(12-fold
average),
leading
bright
single-photon
rates
1.45
±
0.1
MHz
first
lens.
Moreover,
demonstrated
allowed
push
wavelength
reliably
around
810
nm
enables
free-space
communication.
Nano Letters,
Год журнала:
2023,
Номер
23(18), С. 8643 - 8649
Опубликована: Сен. 6, 2023
Understanding
ultrafast
electronic
dynamics
of
the
interlayer
excitonic
states
in
atomically
thin
transition
metal
dichalcogenides
is
importance
engineering
valleytronics
and
developing
integrated
circuits.
In
this
work,
we
experimentally
explored
indirect
monolayer
type
II
WSe2/ReS2
heterojunctions
using
time-resolved
photoemission
electron
microscopy,
which
reveals
its
anisotropic
behavior.
The
cooling
decay
excited-state
electrons
exhibit
significant
linear
dichroism.
ab
initio
theoretical
calculations
provide
unambiguous
evidence
that
dichroism
result
primarily
associated
with
nonradiative
recombination
states.
Measuring
energy
spectra,
have
further
revealed
evolution
findings
important
implications
for
controlling
moiré
effects
designing
optoelectronic
devices.
The Journal of Physical Chemistry Letters,
Год журнала:
2023,
Номер
14(9), С. 2277 - 2283
Опубликована: Фев. 24, 2023
We
explore
a
new
platform
for
realizing
excitonic
insulators,
namely
van
der
Waals
(vdW)
bilayers
comprising
two-dimensional
Janus
materials.
In
previous
studies,
type
II
heterobilayers
have
been
brought
to
the
insulating
regime
by
tuning
band
alignment
using
external
gates.
contrast,
presented
here
represent
intrinsic
insulators.
first
conduct
ab
initio
calculations
obtain
quasiparticle
structures,
screened
Coulomb
interaction,
and
interlayer
exciton
binding
energies
of
bilayers.
These
initio-derived
quantities
are
then
used
construct
BCS-like
Hamiltonian
condensate.
By
solving
mean-field
gap
equation,
we
identify
16
vdW
with
ground
states
superfluid
properties.
Our
expose
class
advanced
materials
that
likely
exhibit
novel
phases
at
low
temperatures
highlight
subtle
competition
between
hybridization,
spin-orbit
coupling,
dielectric
screening
governs
their
Materials Today Electronics,
Год журнала:
2023,
Номер
4, С. 100039 - 100039
Опубликована: Июнь 1, 2023
Presence
of
coherent
'resonant'
tunneling
in
quantum
dot
(zero-dimensional)
-
well
(two-dimensional)
heterostructure
is
necessary
to
explain
the
collective
oscillations
average
electrical
polarization
excitonic
dipoles
over
a
macroscopically
large
area.
This
was
measured
using
photo
excited
capacitance
as
function
applied
voltage
bias.
Resonant
this
definitely
requires
momentum
space
narrowing
charge
carriers
inside
and
that
associated
indirect
excitons,
which
indicates
bias
dependent
'itinerant'
Bose-Einstein
condensation
excitons.
Observation
periodic
variations
negative
points
in-plane
coulomb
correlations
mediated
by
long
range
spatial
ordering
indirect,
dipolar
Enhanced
contrast
interference
beats
waves
even
under
white
light
observed
Rabi
area
also
support
presence
density
driven
having
order.
Periodic
(absence)
splitting
peaks
photocapacitance
spectra
demonstrate
coupling
(decoupling)
between
energy
levels
dots
with
biases,
can
potentially
be
used
for
gate
operations.
All
these
observations
point
experimental
control
large,
state
two-component
condensate
excitons
heterostructure.
Therefore,
principle,
millions
two-level
qubits
intertwined
fabricate
registers
such
hybrid
controlling
local
electric
fields
varying
photoexcitation
intensities
overlapping
spots.
Physical review. B./Physical review. B,
Год журнала:
2024,
Номер
110(5)
Опубликована: Авг. 15, 2024
Using
first-principles
simulations
combined
with
many-body
calculations,
we
show
that
two-dimensional
free-standing
quintuple-layer
(QL)
${\mathrm{Bi}}_{2}{\mathrm{Se}}_{2}\mathrm{Te}$
is
an
inversion-symmetric
monolayer
expected
to
achieve
spatially
indirect
exciton
large
radius,
small
effective
mass,
and
long
lifetime.
Such
system
theoretically
predicted
be
a
promising
platform
for
realizing
excitonic
Bose-Einstein
condensation
superfluid
due
its
high
phase
transition
temperatures
of
$\ensuremath{\sim}257$
$\ensuremath{\sim}64.25$
K
the
degeneracy
superfluid,
respectively.
The
importance
spin-orbit
coupling
revealed,
angular
momentum
selection
rules
photon
absorption
are
discussed.
This
finding
suggests
potential
QL
exotic
bosonic
bound
states
provides
as
tantalizing
high-temperature
probe
physics.