The Journal of Physical Chemistry A,
Год журнала:
2025,
Номер
unknown
Опубликована: Янв. 3, 2025
With
the
rapid
development
of
thermally
activated
delayed
fluorescence
(TADF)
materials,
achieving
efficient
reverse
intersystem
crossing
(RISC)
to
mitigate
triplet–triplet
annihilation
has
emerged
as
a
prominent
research
focus.
This
study
investigates
five
derivative
molecules,
featuring
varied
bridging
atoms/groups
(O,
S,
Se,
−CH2−),
designed
from
reported
TADF
molecule
AC-BO
with
through-space
charge
transfer
(TSCT)
properties.
Utilizing
time-dependent
density
functional
theory
coupled
PCM
solution
model,
their
excited
state
behaviors
were
simulated
in
toluene
environment.
Interestingly,
it
was
observed
that
RISC
and
one
derivative,
AC-BCO,
occurs
predominantly
via
T2
rather
than
typical
T1
(3LEB,
where
B
denotes
fluorene
bridge),
distinguishing
conventional
TSCT-TADF
compounds,
typically
involves
transitions
between
3CT
1CT
states.
distinctive
mode
is
attributed
reduced
spin–orbit
coupling
(SOC)
3LEB,
representing
significant
contributor
process
through
its
character.
Introduction
heavy
atoms
enhances
electron-withdrawing
ability
acceptor
unit,
leading
exhibiting
3MRCT
characteristics
increased
SOC,
thereby
favoring
transitions.
not
only
deepens
our
understanding
transition
mechanisms
compounds
but
also
provides
crucial
insights
into
molecular
design
regulation
triplet
Journal of the American Chemical Society,
Год журнала:
2023,
Номер
145(33), С. 18366 - 18381
Опубликована: Авг. 9, 2023
Triplet-triplet
energy
transfer
(EnT)
is
a
powerful
activation
pathway
in
photocatalysis
that
unlocks
new
organic
transformations
and
improves
the
sustainability
of
synthesis.
Many
current
examples,
however,
still
rely
on
platinum-group
metal
complexes
as
photosensitizers,
with
associated
high
costs
environmental
impacts.
Photosensitizers
exhibit
thermally
activated
delayed
fluorescence
(TADF)
are
attractive
fully
alternatives
EnT
photocatalysis.
However,
TADF
photocatalysts
incorporating
heavy
atoms
remain
rare,
despite
their
utility
inducing
efficient
spin-orbit-coupling,
intersystem-crossing,
consequently
triplet
population.
Here,
we
describe
synthesis
imidazo-phenothiazine
(IPTZ),
sulfur-containing
heterocycle
locked
planar
structure
shallow
LUMO
level.
This
acceptor
used
to
prepare
seven
TADF-active
energies
up
63.9
kcal
mol-1.
We
show
sulfur
incorporation
spin-orbit
coupling
increases
lifetimes
3.64
ms,
while
also
allowing
for
tuning
photophysical
properties
via
oxidation
at
atom.
These
IPTZ
materials
applied
five
seminal
reactions:
[2
+
2]
cycloaddition,
disulfide-ene
reaction,
Ni-mediated
C-O
C-N
cross-coupling
afford
etherification,
esterification,
amination
products,
outcompeting
industry-standard
photocatalyst
2CzPN
four
studied
scenarios.
Detailed
theoretical
studies
understand
structure-activity
relationships
demonstrate
key
role
atom
effect
design
superior
photocatalytic
performance.
Materials Chemistry Frontiers,
Год журнала:
2023,
Номер
7(14), С. 2809 - 2827
Опубликована: Янв. 1, 2023
The
underlying
molecular-level
insights
into
the
structure–property
relationship
for
narrowband
emission,
high
photoluminescence
efficiency
and
emission
color
tunability
of
organic
MR-TADF
emitters
are
organized
both
in
experiment
theory.
Multiple
resonance
(MR)
compounds
have
garnered
substantial
attention
for
their
prospective
utility
in
wide
color
gamut
displays.
Nevertheless,
developing
red
MR
emitters
with
both
high
efficiency
and
saturated
emission
remains
demanding.
We
herein
introduce
a
comprehensive
strategy
spectral
tuning
the
region
by
simultaneously
regulating
π-conjugation
electron-donating
strengths
of
double
boron-embedded
skeleton
while
preserving
narrowband
characteristics.
The
proof-of-concept
materials
manifested
emissions
from
orange-red
to
deep
red,
bandwidths
below
0.12
eV.
pure-red
device
based
on
CzIDBNO
displayed
superior
purity
CIE
coordinates
(0.701,
0.298),
approaching
Broadcast
Television
2020
standard.
In
concert
photoluminescence
quantum
yield
strong
horizontal
dipole
orientation,
also
achieved
maximum
external
32.5%
current
20.2
cd
A-1,
outstripping
prior
reported
organic
light-emitting
diodes
(OLEDs)
CIEx
exceeding
0.68.
These
findings
offer
roadmap
designing
high-performance
exceptional
future
OLED
material
research
advancements.
Advanced Functional Materials,
Год журнала:
2023,
Номер
34(6)
Опубликована: Окт. 25, 2023
Abstract
The
development
of
thermally
activated
delayed
fluorescence
(TADF)
polymers
with
narrowband
emission,
particularly
in
the
blue
region,
remains
a
formidable
challenge.
Herein,
new
approach
is
demonstrated
for
TADF
conjugated
by
integrating
multiresonance
moiety
into
backbone.
All
exhibit
characteristics
emission
full‐width
at
half‐maximums
(FWHMs)
23
nm.
solution‐processed
OLEDs
based
on
these
achieve
maximum
external
quantum
efficiency
(EQE
max
)
17.9%
peak
479
nm
and
FWHM
28
main‐chain
type
MR‐TADF
polymer
shed
light
emissive
polymers.
Advanced Optical Materials,
Год журнала:
2024,
Номер
12(11)
Опубликована: Фев. 28, 2024
Abstract
Multi‐resonance
thermally
activated
delayed
fluorescence
(MR‐TADF)
molecules
have
attracted
much
attention
in
the
academia
owing
to
their
unique
photoelectrical
properties.
However,
MR‐TADF
emitters
usually
show
slow
reverse
intersystem
crossing
(RISC)
rate,
resulting
high
efficiency
roll‐off
of
organic
light‐emitting
diodes
(OLEDs)
and
seriously
limiting
further
development.
Here,
a
peripheral
selenium
(Se)
modification
is
presented
for
promote
RISC
process
while
keeping
narrowband
emission
high‐performance
blue
OLEDs.
Compared
parent
(NBN
t
BuNBN),
SeNBN
Se
BuNBN
exhibited
narrower
full‐width
at
half
maximum
(FWHM)
value
23
nm
more
obvious
properties
with
up
86%,
shorter
lifetime
2.4
µs
as
well
faster
rate
3.34×10
5
s
−1
.
Therefore,
OLEDs
based
on
these
two
modified
are
achieved
external
quantum
(EQE)
25.5%
extremely
suppressed
roll‐offs
3.9%
100
cd
m
−2
24.4%
1000
This
work
demonstrated
that
introduction
atom
can
achieve
semiconductors
both
fast
constant
optoelectronic
devices.
Accounts of Materials Research,
Год журнала:
2024,
Номер
5(2), С. 136 - 145
Опубликована: Фев. 7, 2024
ConspectusThe
Nobel
Prize
in
Chemistry
2023
was
awarded
to
Moungi
G.
Bawendi,
Louis
E.
Brus,
and
Aleksey
Ekimov
for
the
discovery
synthesis
of
quantum
dots
(QDs).
Since
QDs
1980s,
endeavors
have
been
put
improve
synthetic
strategies
with
controllable
sizes,
crystal
structures,
surfaces.
With
development
about
half
a
century,
used
multiple
optoelectronic
applications,
which
are
based
on
conversion
between
one
photon
exciton.
In
this
case,
photons
energies
lower
than
bandgap
cannot
be
absorbed
by
semiconductors.
For
example,
solar
cells
or
photocatalysts
transparent
sub-bandgap
near-infrared
(NIR)
light
spectrum,
rendering
transmission
loss.Photon
upconversion
(PUC),
combination
low-energy
high-energy
one,
plays
critical
role
reshaping
spectrum
mitigating
energy
loss.
Among
different
achieve
PUC,
QD
sensitized
triplet–triplet
annihilation
PUC
exhibits
high
response
irradiation,
makes
it
an
ideal
strategy
conversion.Here,
we
introduce
QD-sensitized
emphasize
how
is
applied
conversion.
This
Account
starts
introduction
acting
as
active
materials
directly
convert
electricity
chemical
bonds
due
strong
absorptivity,
flexible
tunable
surface
chemistry,
capability
accommodating
transferring
electrons/holes.
Then
move
can
upconvert
NIR
under
one-sun
condition.
We
discuss
deconvolution
total
QY
into
efficiencies
triplet
transfer
from
sensitizers
organic
emitters,
annihilation,
singlet
emission
emitters.
Next,
summarize
progress
PUC-enhanced
photovoltaics
photochemical
reactions.
photovoltaics,
two
examples
that
beyond
1100
nm,
possible
couple
Si-based
cells.
reactions,
discussion
separated
visible-to-ultraviolet
ultraviolet
light-triggered
reactions
NIR-to-visible
visible
last
section,
point
out
challenges
future
directions
field.
low
solid-state
reabsorption
must
overcome
photovoltaic
application,
more
types
PUC-assisted
explored.
also
propose
other
potential
applications
such
biological
imaging
phototherapy.
hope
will
help
readers
understand
systems
promote
application
efficient
beyond.
Journal of the American Chemical Society,
Год журнала:
2025,
Номер
unknown
Опубликована: Янв. 20, 2025
Implanting
heteroatoms
into
organic
π-conjugated
molecules
(OCMS)
offered
a
great
opportunity
to
fine-tune
the
chemical
structures
and
optoelectronic
properties.
This
work
describes
new
family
of
1,4-azaphosphinines
with
extended
σ–π
hyperconjugations.
The
photophysical
studies
revealed
that
azaphosphinines
exhibited
narrow-band
thermally
activated
delayed
fluorescence
(TADF)
(
full
width
at
half-maximum:
26–40
nm).
According
orbital
localization
analysis
natural
bond
analysis,
effective
σ*−π*
hyperconjugation
is
believed
induce
multiple-resonance
(MR)
TADF,
which
distinct
from
p−π
conjugation-induced
MR-TADF
in
BN
systems.
Although
having
large
ΔES1–T1s
(>3.0
ev),
study
suggested
σ*−π
endowed
system
structural
vibration
favorable
for
spin-vibronic-assisted
RISC.
Having
tunable
p-centers
(lp,
O,
S,
Se,
Me+),
showed
fine-tuned
TADF.
Generally,
strong
hyperconjugations
small
ΔES1–T1s,
efficient
RISCs,
high
PLQYs.
Leveraging
on
hyperconjugations,
TADF
emission
spanned
UV-blue
green.
Particularly,
photoluminescence
quantum
yields
(74%
toluene
92%
10%
doped
PMMA).
As
proof
concept,
two
PO
center
were
applied
as
light-emitting
materials
lighting-emitting
diodes.
devices
UV-
deep-blue
EQE
10.3%.
current
us
strategy,
namely,
hyperconjugation-induced
MR-TADF,
designing
OCMs
Advanced Optical Materials,
Год журнала:
2023,
Номер
11(24)
Опубликована: Июль 21, 2023
Abstract
Multi‐resonance
(MR)
based
organoboron
emitters
exhibiting
high‐efficiency
narrowband
thermally
activated
delayed
fluorescence
(TADF)
have
become
a
critical
material
component
for
constructing
high‐performance
organic
light‐emitting
diodes
(OLEDs)
with
high
color
purity
and
gamut.
However,
most
of
the
MR‐TADF
devices
suffer
from
severe
efficiency
roll‐off
at
current
density
due
to
relatively
large
singlet–triplet
splitting
energy,
long
excited
state
lifetime,
slow
reverse
intersystem
crossing
rate
(
k
RISC
).
Herein,
by
utilizing
sulfur
atom‐fused
donor
unit,
7
H
‐benzo[4,5]thieno[2,3‐b]carbazole,
an
boron
emitter
(BTC‐BNCz)
capable
low
TADF
emission
is
developed.
Benefitting
heavy
atom
effect
atom,
up
1.6
×
10
5
s
−1
achieved,
which
could
greatly
reduce
undesired
quenching
effect.
Consequently,
OLED
using
BTC‐BNCz
as
dopant
exhibits
external
quantum
(EQE)
27.0%
full
width
half
maximum
(FWHM)
35
nm.
Moreover,
horizontal
dipole
ratio
assistant
host,
outstanding
device
performance
achieved
EQE
35.2%
FWHM
37
nm,
featuring
roll‐off.