The Journal of Physical Chemistry A,
Journal Year:
2025,
Volume and Issue:
unknown
Published: Jan. 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,
Journal Year:
2023,
Volume and Issue:
145(23), P. 12550 - 12560
Published: June 5, 2023
Multiple
resonance
thermally
activated
delayed
fluorescence
(MR-TADF)
emitters
are
promising
candidates
for
narrowband
organic
light-emitting
diodes,
but
their
electroluminescent
performance
is
typically
hindered
by
the
slow
reverse
intersystem
crossing
rate
(kRISC).
Herein,
we
present
an
effective
strategy
to
introduce
a
multichannel
(RISC)
pathway
with
large
spin-orbit
coupling
orthogonally
linking
electron-donating
unit
MR
framework.
Through
delicate
manipulation
of
excited-state
energy
levels,
additional
intersegmental
charge
transfer
triplet
state
could
be
"silently"
induced
without
perturbing
character
lowest
excited
singlet
state.
The
proof-of-concept
emitter
CzBN3
not
only
affords
23-fold
increase
kRISC
compared
its
prototypical
skeleton
also
realizes
close-to-unity
photoluminescence
quantum
yield,
radiative
constant,
and
very
narrow
emission
spectrum.
These
merits
enable
high
maximum
external
efficiency
(EQEmax)
up
37.1%
alleviated
roll-off
in
sensitizer-free
device
(EQE1000
=
30.4%),
further
boost
(EQEmax/1000
42.3/34.1%)
realized
hyperfluorescent
device.
state-of-the-art
validates
superiority
our
molecular
design
strategy.
Advanced Functional Materials,
Journal Year:
2023,
Volume and Issue:
33(50)
Published: Aug. 7, 2023
Abstract
Multi‐resonance
thermally
activated
delayed
fluorescence
(MR‐TADF)
emitters
have
drawn
considerable
attention
because
of
their
remarkable
optoelectronic
properties
high
emission
efficiency
and
narrow
profile,
represent
an
active
subject
cutting‐edge
research
in
the
organic
electroluminescence
(EL).
However,
slow
reverse
intersystem
crossing
(RISC)
rate
MR‐TADF
emitter
caused
by
large
energy
gap
(Δ
E
ST
)
small
spin‐orbit
coupling
(SOC)
matrix
elements
between
singlet
triplet
excited
states
limits
further
development
EL
devices.
Currently,
innovative
molecular
design
strategies
been
developed
including
heavy
atom
integration,
π‐extended
MR
framework
metal
perturbation,
so
on
to
improve
RISC
process
for
high‐performance
Here,
overview
is
presented
recent
progress
with
fast
(
>
10
−5
s
−1
),
particular
design,
properties,
device
performance
light‐emitting
diodes
(OLEDs),
which
intends
systematize
knowledge
this
thriving
highly
efficient
emitters.
Finally,
challenges
future
prospects
materials
are
discussed
comprehensively.
Chemical Communications,
Journal Year:
2023,
Volume and Issue:
59(25), P. 3685 - 3702
Published: Jan. 1, 2023
The
hunt
for
narrow-band
emissive
pure
organic
molecules
capable
of
harvesting
both
singlet
and
triplet
excitons
light
emission
has
garnered
enormous
attention
to
promote
the
advancement
light-emitting
diodes
(OLEDs).
Over
past
decade,
thermally
activated
delayed
fluorescence
(TADF)
materials
based
on
donor
(D)/acceptor
(A)
combinations
have
been
researched
OLEDs
in
wide
color
gamut
(RGB)
regions.
However,
due
strong
intramolecular
charge-transfer
(CT)
state,
they
exhibit
broad
with
full-width-at-half
maximum
(FWHM)
>
70
nm,
which
deviates
from
being
detrimental
achieving
high
purity
future
high-end
display
electronics
such
as
high-definition
TVs
ultra-high-definition
(UHDTVs).
Recently,
new
development
sub-class
TADF
emitters
called
multi-resonant
(MR-TADF)
boron/nitrogen
atoms
attracted
much
interest
ultra-high
definition
OLEDs.
Consequently,
MR-TADF
are
appeal
their
potentiality
promising
candidates
fabricating
high-efficient
numerous
advantages
photoluminescence
quantum
yield
(PLQY),
unprecedented
purity,
narrow
bandwidth
(FWHM
≤
40
nm).
Until
now
many
developed
ultra-gamut
regions
different
design
concepts.
most
MR-TADF-OLEDs
showed
ruthless
external
efficiency
(EQE)
roll-off
characteristics
at
brightness.
Such
EQE
were
derived
mainly
low
reverse
intersystem
crossing
(kRISC)
rate
values.
This
feature
article
primarily
focuses
strategies
improve
kRISC
some
supportive
including
extending
charge
delocalization,
heavy
atom
introduction,
multi-donor/acceptor
utilization,
a
hyperfluorescence
system
approach.
Furthermore,
outlook
prospects
developments
skeletons
described.
Angewandte Chemie International Edition,
Journal Year:
2023,
Volume and Issue:
62(25)
Published: March 8, 2023
Ultraviolet
(UV,
λ<400
nm)
light
is
essential
for
various
photochemical
reactions,
but
its
intensity
in
the
solar
spectrum
very
low,
and
sources
that
artificially
generate
high-energy
UV
are
inefficient
environmentally
unfriendly.
A
solution
to
this
problem
photon
upconversion
(UC)
from
visible
(vis,
λ>400
light.
Among
several
mechanisms,
UC
based
on
triplet-triplet
annihilation
(TTA-UC)
particular
has
made
remarkable
progress
recent
years.
The
development
of
new
chromophores
enabled
highly
efficient
conversion
low-intensity
into
In
review,
we
summarize
visible-to-UV
TTA-UC,
their
production
films
application
processes
such
as
catalysis,
bond
activation
polymerization.
Finally,
challenges
opportunities
future
material
applications
will
be
discussed.
Angewandte Chemie International Edition,
Journal Year:
2023,
Volume and Issue:
62(25)
Published: April 18, 2023
Triplet-triplet
annihilation
upconversion
(TTA-UC)
with
near-infrared
(NIR)
photosensitizers
is
highly
desirable
for
a
variety
of
emerging
applications.
However,
the
development
NIR-to-blue
TTA-UC
large
anti-Stokes
shift
extremely
challenging
because
energy
loss
during
intersystem
crossing
(ISC).
Here,
we
develop
first
NIR-absorbing
B,N-heteroarene-based
sensitizer
(BNS)
multi-resonance
thermally
activated
delayed
fluorescence
(MR-TADF)
characters
to
achieve
efficient
TTA-UC.
The
small
gap
between
singlet
and
triplet
excited
states
(0.14
eV)
BNS
suppresses
ISC
loss,
its
long-delayed
lifetime
(115
μs)
contributes
transfer.
As
result,
largest
(1.03
among
all
heavy-atom-free
NIR-activatable
systems
obtained
high
quantum
yield
2.9
%
(upper
limit
50
%).
Materials Chemistry Frontiers,
Journal Year:
2023,
Volume and Issue:
7(19), P. 4304 - 4338
Published: Jan. 1, 2023
This
review
focuses
on
fused-ring
carbazole
derivatives,
their
molecular
design,
electronic
and
photophysical
properties,
applications
as
the
emitter
and/or
host
material
in
organic
light
emitting
diodes
(OLEDs).
Journal of Materials Chemistry C,
Journal Year:
2023,
Volume and Issue:
11(20), P. 6471 - 6511
Published: Jan. 1, 2023
MR-TADF
emitters
with
narrow
emission
have
been
developed
and
are
expected
to
become
fourth-generation
for
HD-OLEDs,
molecular
design
guidelines
commercial
prospects
outlined
in
this
review.
