Rational design of thermally activated delayed fluorescence emitters with aggregation-induced emission employing combined charge transfer pathways for fabricating efficient non-doped OLEDs

Article abstract of DOI:10.1039/c9tc02467k

The development of luminescent materials simultaneously possessing thermally activated delayed fluorescence (TADF), aggregation-induced emission (AIE), and high luminescence efficiency in the solid state is urgent for fabricating efficient non-doped organ

Full text of DOI:10.1039/c9tc02467k

View Article Online
View Journal
Journal of
Materials Chemistry C
Materials for optical, magnetic and electronic devices
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: F. Ma, Y. Cheng,
Y. Zheng, H. Ji, K. Hasrat and Z. Qi, J. Mater. Chem. C, 2019, DOI: 10.1039/C9TC02467K.
Volume
Number
6
5
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
7
February 2018
Pages 911-1266
Journal of
Materials Chemistry C
Materials for optical, magnetic and electronic devices
rsc.li/materials-c
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 2050-7526
PAPER
Nosang V. Myung, Yong-Ho Choa et al.
A
noble gas sensor platform: linear dense assemblies of
a multi-layered
single-walled carbon nanotubes (LACNTs) in
ceramic/metal electrode system (MLES)
rsc.li/materials-c

Page 1 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
Rational design of thermally activated delayed fluorescence emitters with
aggregation-induced emission employing combined charge transfer
pathways for efficient non-doped OLEDs
a
a
a
a
a
a
Fulong Ma , Yu Cheng , Yu Zheng , Hefang Ji , Kamvan Hasrat , Zhengjian Qi
aJiangsu Province Hi-Tech Key Laboratory for Biomedical Research, School of Chemistry and Chemical Engineering, Southeast
University, Nanjing, Jiangsu 211189, PR China
Abstract: Development of luminescent materials simultaneously possessing thermally activated
delayed fluorescence (TADF), aggregation-induced emission (AIE) and high luminescence
efficiency in solid state are urgent for efficient non-doped organic light-emitting diodes (OLEDs).
Herein, two novel emitters bearing triphenylamine as donor moiety and phenyl ketone as acceptor
unit, named DTPA-DTM and DTPA-DDTM are designed and synthesized. Combined change
transfer pathways in single molecule are achieved through linking the donor and acceptor units in
ortho position, which is favorable for reducing singlet-triplet splitting (E ) and increasing
st
luminescence efficiency. The TADF characteristics, AIE properties, solvatochromism, theoretical
calculation, together with crystallography of the designed emitters are investigated systematacially
to explore the structure-properties relationship. By virtue of the inhibited concentration quenching
in solid state, the non-doped OLEDs employed DTPA-DDTM as emitter along realizing a high
current efficiency (LE) and external quantum efficiency (EQE) of 25.6 cd/A and 8.2%,
respectively. The obtained results clearly demonstrate that combining charge-transfer pathways in
single molecule is a promising strategy to construct high efficient TADF emitters used for
fabricating non-doped organic light emitting diodes.
Introduction
Thermally activated delayed fluorescent materials have emerged as the most
promising candidate for constructing high-performance OLEDs due to the efficient
harvest of both singlet and triplet excitons through reverse intersystem crossing
(
RISC) process.1-7 The basic principle of designing TADF materials is separating the

Corresponding author. E-mail address: qizhengjian@seu.edu.cn (Z. Qi).

Journal of Materials Chemistry C
Page 2 of 23
View Article Online
DOI: 10.1039/C9TC02467K
highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular
orbital (LUMO) for minimizing the electron exchange energy and yielding a small
8
-10

E .
st
The widely applied strategy is to link the donor and acceptor units with a
highly twist bridge and therefore the E is decreased through the formed strong
st
charge transfer (CT) process. Recently, numerous efficient TADF materials adopting
donor-acceptor (D-A) structure with charge transfer characteristic have been
exploited.11-17 Normally, the process of charge transfer can be explained in two types
according to the electron interaction manner, namely through-bond charge transfer
(
TBCT) and through-space charge transfer (TSCT).18-23 The molecule possessing
TBCT usually adopts the skeleton that donor and acceptor moieties are linked directly
through strong covalent bond. Different from TBCT, TSCT occurs via D-A π-π
interaction through space between donor and acceptor units.19, 20, 22 Recently, in
addition to the above charge transfer processes, the strategy of combining dual charge
transfer pathways (through-bond and through-space charge transfer) in single TADF
molecule, which is favorable for reducing the singlet-triplet energy splitting (Est)
and achieving high radiative efficiency simultaneously, also seems to a promising
strategy to design novel efficient TADF emitter used for constructing
high-performance OLEDs.24
Generally, most of the efficient TADF emitters are employed by doping in host
materials for fabricating device to suppress the energy loss result from singlet-triplet
or triplet-triplet annihilation processes.24-27 In this case, appropriate selection of the
host materials and precise control of the ratio between the host and guest components
should be considered elaborately, leading to the fabrication process more complex and
unreliable. Moreover, the blending system including the host and guest materials have
the potential risk of phase separation which will harm the device stability during
operation process. Given these problems, much research has performed to develop
TADF materials as emitting layer along in OLEDs based on the delicate design of
molecular structure to eliminate the concentration quenching effect in solid state.28-32
Among these strategies, the luminescent materials with aggregation-induced emission

Page 3 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
(
AIE) features which exhibit strong emission in solid state, have been considered as
the promise candidate for host-free OLEDs.33-45 Therefore, the development of novel
TADF materials with AIE properties is significant for non-doped OLEDs, meanwhile
exploring the relationship between molecular structures and their charge transfer
features.
Herein, we demonstrate two efficient TADF emitters with aggregation-induced
emission (AIE) properties bearing triphenylamine as donor moiety and phenyl ketone
as acceptor unit. By virtue of the delicately designed molecular structure, these
emitters DTPA-DTM and DTPA-DDTM are expected to equip the following features.
First, the distance between the adjacent ortho-linked donor and acceptor units are
proximal, therefore through-space electron interaction can occur to minimize the
singlet-triplet energy splitting (E ) and yield TADF property. Second, unlike
st
conventional TADF emitters, the electron clouds of HOMO and LUMO of these
emitters are not only overlapped around the linking bridge, meanwhile, the electron
clouds of LUMO are partially extended to the ortho donor unit through spatial π-π
interaction, which is favorable for facilitating the radiative transition premised for
enhancing efficiency. Finally, the highly twisted molecular configurations with weak
intermolecular interactions allow them to exhibit the AIE effect and produce high
luminescence efficiency in solid state, which is significant in fabricating non-doped
device. As a consequence, because of the relatively high PLQY (60.5%) and obvious
TADF characteristics in solid state, the non-doped device employed DTPA-DDTM as
emitter exhibits a high current efficiency (LE) and external quantum efficiency (EQE)
of 25.6 cd/A and 8.2%, respectively.
Results and discussion
Synthesis and characterization
These emitters are designed and prepared through linking the donor and acceptor
moieties in ortho position around the central phenyl core. One is DTPA-DTM with
single acceptor and another is DTPA-DDTM which containing dual acceptors to

Journal of Materials Chemistry C
Page 4 of 23
View Article Online
DOI: 10.1039/C9TC02467K
explore the influence of charge transfer strength on photophysical properties. The
synthesized routes of DTPA-DTM and DTPA-DDTM were shown in Scheme 1. The
key intermediates DBr-DTM and DBr-DDTM were synthesized from the
corresponding bromo-substituted benzoic acid through acyl chlorination and
Friedel-Crafts reactions. Then the corresponding intermediates were reacted with
(4-(diphenylamino)phenyl)boronic acid to get the target products by means of Suzuki
reaction. The TADF emitters were purified through column chromatography before
measurements and device fabrication processes. The molecule structures were
certified through H and 13C NMR spectroscopies, mass spectrometry and single
crystal.
1
2 3
Scheme 1 Synthetic routes of DTPA-DTM and DTPA-DDTM: (ⅰ) SOCl , reflux; (ⅱ) Dibenzothiophene, AlCl ,
rt; (ⅲ) Pd(PPh , K CO , toluene, alcohol, H O, 110℃.
3
)
4
2
3
2
Crystal Structure
A block-like single crystal of DTPA-DDTM was successfully grown from the
mixed solution of hexane and dichloromethane at room temperature by slow solvent
evaporation. The structure of the molecule was analysed through single-crystal X-ray
diffraction. As shown in Fig. 1, the molecular structure exhibited highly steric
hindrance by virtue of the ortho linking between donor and acceptor units, which was
beneficial for separating HOMO and LUMO and yielding a small E . Furthermore,
st
the donor triphenylamine showed strong intramolecular space interaction with
acceptor moiety with a distance of 3.03-4.04 Å. The molecular packing pattern of

Page 5 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
DTPA-DDTM in crystals was also displayed in Fig. 1. On account of the highly
twisted conformation, no close π–π stacking was appeared and the molecules were
piled up loosely. Multiple C-H···π and C=O···H hydrogen bonds with distances of
2
.64-3.34 Å can be found, which was effective for locking intramolecular motions
and rigidifying molecular structures.33, 38 The intra- and intermolecular interactions of
DTPA-DDTM will effectively suppress the nonradiative decay and enhance the
radiative efficiency in solid state. Even though the crystal structure of DTPA-DTM
was not obtained, it can be predicted that DTPA-DDTM with dual acceptor units
possessing enhanced intramolecular space interaction than that of DTPA-DTM.
Therefore, DTPA-DDTM displayed intensive molecular rigidity than that of
DTPA-DTM.
Fig. 1 Single crystal structure (a) and packing mode (b), (c) of DTPA-DDTM.
Photophysical properties
Photophysical properties of the emitters were crucial to investigate the relationship
between the designed molecular structure and the effect of intermolecular interaction.
The UV-vis absorption and fluorescence spectra of the compounds measured in
different solvents and solid film were presented in Fig. 2. The summarized
photophysical data were shown in Table 1 and Table S1. As shown in Fig. S1, the
absorption of these emitters in different solvents exhibited the similar features and
changed scarcely. The high energy absorption band below 330 nm can be attributed to
*
π-π transition of the conjugated skeletons. Meanwhile, the long wavelength

Journal of Materials Chemistry C
Page 6 of 23
View Article Online
DOI: 10.1039/C9TC02467K
absorption located on around 351 nm and 403 nm for DTPA-DTM and
DTPA-DDTM, respectively, can be ascribed to the intramolecular charge transfer
(ICT) from donor to acceptor units. In toluene solution, the maximum emission peak
of DTPA-DTM was 474 nm, while the maximum emission peak in neat solid film
state was shift to 498 by 22 nm, which was mainly resulted from the severe π-π
stacking between the adjacent molecules. As for the molecule with dual functional
acceptor moieties, the emission peaks were appeared at 533 and 539 nm in solution
and neat film state, respectively. The limited bathochromic shift with only 6 nm of
DTPA-DDTM was reasonable when considering the higher twist molecular structure
after the incorporation of the dual acceptor units, which reduced the intermolecular
interaction in solid state. Compared with neat films, the blue shifts of DTPA-DTM
and DTPA-DDTM were 18nm and 12nm at the same doping concentration of 10
wt%, indicating the reduced interaction between the molecules of DTPA-DDTM than
DTPA-DTM. The PL spectra of these TADF emitters were also measured in different
solvents with increased polarity from hexane to dichloromethane. As shown in Fig. 2,
the maximum emission peaks displayed clear bathochromic shift with increased
solvent polarity. Meanwhile, the PL spectra became broad gradually with the
increased polarity of the solvents, which indicated the obvious solvatochromic effect
of DTPA-DTM and DTPA-DDTM. To deepen the understanding of excited state
properties, the Stokes shift ( –  ) of DTPA-DTM and DTPA-DDTM against
a
f
solvent orientation polarizability (f) was plotted according to the Lippert-Mataga
model:46
(
―
)2
푔
푎3

푒
0
0
(
ℎ푐 푎 ― 푓
)
= ( ― 푓) ―
∆푓 ，푛
( )
푎
(
)
― 1
푛2 ― 1

∆푓
(
，푛
)
=
―
2
2
 ― 1 2푛 + 1

Page 7 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
where h is the Planck constant, f(,n) is the orientational polarizability of the
0
0
solvents, c is the speed of light in vacuum,  –  is the Stokes shift,  – is the
a
f
a
f
stokes shift when f(,n) is zero,  and  are the dipole moments in the excited and
e
g
ground states, respectively. a is the radius of the chromophore, and ε and n are the
dielectric and refractive index of the solvent, respectively. According to the plots of
(
 –  ) vs. f, both DTPA-DTM and DTPA-DDTM obeyed the linear relationship
a f
with notable positive slopes. These observations clearly illustrated that these
compounds had a small dipole moment in the ground state and a high dipole moment
in the excited CT state.47
The phosphorescence spectra were measured in toluene at 77 K, as shown in Fig.
3
(a), the triplets were 2.74/2.48 eV calculated from the high-energy vibronic peak of
DTPA-DTM and DTPA-DDTM, respectively.48 The singlets were 2.91/2.64 eV
calculated from the onset of the broad emission bands of DTPA-DTM and
DTPA-DDTM, respectively. Therefore, the E were calculated to be 0.18/0.17 eV,
st
which were sufficiently small for the reverse intersystem crossing process from
triplets to singlets. The E were also measured to be 0.28/0.19 eV according to the
st
phosphorescence and fluorescence spectra in neat film states.
Fig. 2 (a) The UV-vis absorption and fluorescence spectra measured in toluene (10-5 M) and fluorescence of neat
film at room temperature. Fluorescence spectra of DTPA-DTM (b) and DTPA-DDTM (c) in different solvents at
room temperature. (d) Plot of stocks shift versus orientation polarization (f) of the solvent.

Journal of Materials Chemistry C
Page 8 of 23
View Article Online
DOI: 10.1039/C9TC02467K
Table 1 Photophysical properties of DTPA-DTM and DTPA-DDTM.
HOMOf/
E
푔
g
λabsa
nm]
λema λemb λemc ϕFd
τ /τ
e
e
Esth
i
i
p
d
S /T /
g /
푇 푇
d
1
1
Compound
DTPA-DTM
f
LUMO [eV]
[eV]
[eV]
[
[nm] [nm] [nm] [%] [ns]/[μs]
[
℃]
304,352 474
498
539
480 38.6
6.8/1.6
5.35/2.65 2.70 2.91/2.74/0.18 117/430
DTPA-DDTM 301,404 533
527 60.5
17.8/2.4
5.35/2.74 2.61 2.64/2.48/0.17 170/485
aMeasured in toluene. Measured in neat film. Measured in 10 wt% emitter doped mCP film. Measured in neat
b
c
d
e
film using integrating sphere under nitrogen. The prompt and delayed fluorescence lifetimes of the neat film at
f
+
room temperature. Obtained from the cyclic voltammograms. The oxidation potential of Fc/Fc was measured to
푂푋
. gObtained from the onsets of absorption
g
be 0.35 V. HOMO = ‒ (4.8 + 퐸표푛푠푒푡 ―0.35) eV，LUMO = HOMO + E
h
i
-1
spectra. Obtained in toluene at 77 K. Measured by DSC/TGA at a heating rate of 10℃ min .
Thermally activated delayed fuorescence (TADF) properties
Since the photophysical properties in neat film state of emitter were highly
important for fabricating non-doped OLEDs, therefore the transient PL decay spectra
were measured in depositional neat thin films. As shown in Fig. 3(b), both emitters
displayed bi-exponential decays including prompt and delayed components in neat
films at room temperature. The short lifetime components of DTPA-DTM and
DTPA-DDTM with 6.8 and 17.8 ns, respectively, can be attributed to the
conventional fluorescence. The long delayed components of them with 1.6 and 2.4 s,
respectively, corresponded to the transition of delayed S from the non-radiative T
1
1
state through reverse intersystem crossing (RISC) process on account of the
sufficiently small singlet-triplet splitting. Besides, the transient PL decay spectra in
degassed toluene solution were nmeasured. DTPA-DDTM shown the similar decay
characteristics in neat film and solution, however, DTPA-DTM displayed more
obvious delayed fluorescence characteristics in solution than neat film, which was
resulted from the higher twist structure of DTPA-DDTM induced reduced
concentration quenching in solid state. The temperature-dependent transient decay
spectra were also performed to further confirm the TADF characteristics. As shown in
Fig. S2, the delayed components of the two emitters improved obviously with the

Page 9 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
increased temperature from 200 K to 300 K, which ensured that the delayed
components were from the singlet convert from the triplet under thermal activation.
The phenomenon was consistent with the TADF emitters reported previously.49, 50 In
order to further explore the emissive properties, the PLQYs were measured in pure
film state. The PLQYs of DTPA-DTM and DTPA-DDTM were 38.6% and 60.5%,
respectively. Compared with DTPA-DTM, the improved performance of PL quantum
yield of DTPA-DDTM in solid state can be attributed to the effectively suppressed
intramolecular vibration relaxation resulted from enhanced intramolecular D-A
interaction effect. The time-resolved photoluminescence spectra were carried out in
toluene under nitrogen at room temperature. As shown in Fig. S4, the similar spectra
of prompt and delayed demonstrated that the delayed fluorescence was stemmed from
the S state through reverse intersystem crossing. These results certified that the
1
incorporation of dual functional acceptor units in single molecule can not only
improved the performance of PLQY via enhancing intramolecular D-A interaction,
but also reduced the intermolecular interaction through regulating the twist
configuration, making the designed TADF emitters more suitable for fabricating
efficient non-doped OLEDs. To further explore the effect of enhanced intramolecular
interaction stemmed from dual acceptor fragments on transition rate constants, the
processes of ISC, RISC, radiative transition and non-radiative transition (k , kRISC,
ISC
k , k ) were calculated. The photophysical rate constants were summarized in
r,S
nr,S
Table 2. Compared with DTPA-DTM, the values of kRISC and kr, S of DTPA-DDTM
increased obviously. Meanwhile, the knr, S of DTPA-DDTM was smaller than that of
DTPA-DTM. These results demonstrated that the enhanced intramolecular
interactions were favorable for facilitating radiative transition process and suppressing
the non-radiative transition process.

Journal of Materials Chemistry C
Page 10 of 23
View Article Online
DOI: 10.1039/C9TC02467K
Fig. 3 (a) Phosphorescence spectra measured at 77 K in toluene. (b) The transient PL decay spectra in degassed
toluene and neat film measured at room temperature of DTPA-DTM and DTPA-DDTM.
Aggregation-induced emission (AIE) properties
To confirm the aggregation-induced emission (AIE) activity of the novel emitters,
the PL spectra of DTPA-DTM and DTPA-DDTM were measured in the THF/water
mixed solvents with various THF/water ratio. As shown in Fig. 4(a) and (b),
DTPA-DDTM displayed a weak broad orange emission in pure THF solution. When
the water fraction varied from 10% to 70%, the PL emission was extremely weak.
However, the emission becomes much stronger when increasing the water fraction
from 80% to 99% with slight blue-shifted emission and the intensity was about 12
times higher than that of the original THF solution. The PL spectra of DTPA-DTM
were also measured via increasing the water fraction from 0% to 99% and the similar
behavior was observed. The PLQY of DTPA-DTM and DTPA-DDTM were
measured in pure THF solution with values of 8.4% and 5.1%, respectively, which
was lower than the values in solid state. These results clearly indicated that both
compounds have typical AIE features. Due to the severe aggregation of the
compounds in poor solution of large water fractions, nonradiative decay channel of
the excited states result from the active intramolecular motions can be suppressed,
therefore the intensity of fuorescence enhanced obviously. This phenomenon was
similar to some previously reported AIE emitters which exhibited enhanced

Page 11 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
fluorescence in aggregation state by virtue of the restriction of intramolecular
motion.26, 51 Moreover, the molecules with AIE features were beneficial to suppress
the harmful concentration quenching processes.
Fig. 4 PL spectra of DTPA-DTM (a) and DTPA-DDTM (c) in THF/water mixtures at different water fractions.
0 0
Plots of I/I values versus water fractions of DTPA-DTM (b) and DTPA-DDTM (d). I is the PL intensity in pure
THF solvent. Inset: photos of the emitters in corresponding THF/water mixtures under 365 nm excitation.
Theoretical calculation
In order to explore the relationships between the molecular spatial structure and
electronic property of the designed emitters at molecular level, geometry
configuration and frontier molecular orbitals were investigated using density
functional theory (DFT) calculation at the level of B3LYP/6-31G(d). As shown in
Fig. 5, in the optimized molecular structures, the dihedral angles between the
dibenzothiophene plane and central phenyl ring was 60.4° for DTPA-DDTM, which
were similar to DTPA-DTM (60.7°). Moreover, as shown in Fig. S5, the
ortho-positioned triphenylamine units showed a close proximity with the acceptor
units with the distance of 3.08-4.63 Å, which was slightly larger than the results of
single crystal. The HOMOs of both molecules were thoroughly distributed on the two
triphenylamine groups with a position of para to each other. While the LUMOs
mainly located on the phenyl ketone group and partially extended to the ortho
triphenylamine groups. Therefore, the charge transfer manners were not only through
the covalent bond but also through the space resuled from strong intramolecular D-A
interactions.24 Moreover, compared with DTPA-DTM, DTPA-DDTM with dual
acceptor units exhibited more extensive distribution of the LUMO, which was
5
2
beneficial to improved PL quantum yield. The calculated HOMO/LUMO energy
levels were 4.83/1.78 eV and 4.85/1.85 eV of DTPA-DTM and DTPA-DDTM,
respectively. Based on the time-dependent density functional theory (TD-DFT)
calculations, the S /T energy levels of DTPA-DTM and DTPA-DDTM were
1
1
2
.79/2.60 eV and 2.48/2.35 eV, respectively. The E were estimated to be 0.19 and
st

Journal of Materials Chemistry C
Page 12 of 23
View Article Online
DOI: 10.1039/C9TC02467K
0
.13eV, respectively, which was relatively small to make these molecules as TADF
emitters. Besides, due to the combined charge transfer pathways, these emitters
showed relatively high oscillator strength (f) of ≈0.1, indicating the possibility of
high luminance efficiency. The triplet spin-density distribution (SDD) distributions
were also conducted through DFT calculation for further investigating the influence
of the dual functional acceptor units with more highly twist molecular structure. The
calculated spin densities of the T1 states were mainly distributed on the
triphenylamine moieties and hardly distributed on the side dibenzothiophene part.
Therefore, compared with DTPA-DTM bearing single dibenzothiophene part,
DTPA-DDTM with dual dibenzothiophene parts dampened the interaction of triplets
between adjacent molecules more effective in solid states, which was beneficial for
reducing triplet-triplet annihilation effect.53
1
Fig. 5 The molecular structures, HOMO/LUMO distributions and Spin density distributions of T states of
DTPA-DTM and DTPA-DDTM.
Thermal properties and electrochemical analysis
The thermal properties of DTPA-DTM and DTPA-DDTM were measured by the
thermogravimetric analyzer (TGA) and different scanning calorimeter (DSC). As
shown in Fig. 6, both emitters displayed high decomposition temperatures (T the
d,
temperature corresponding to 5% weight loss of initial value) more than 400 ℃ .
Compared with the T of DTPA-DTM with 430℃, DTPA-DDTM displayed a higher
d
value of 480℃. Meanwhile, The galss transition temperature (T ) of DTPA-DDTM
g

Page 13 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
was 170 ℃ , which was also higher than DTPA-DTM with 117 ℃ . The high Tg
ensured that the materials can form uniform amorphous film during the fabricating
process. The improved thermal stability of DTPA-DDTM demonstrated that the dual
acceptor units were beneficial for increasing the molecular rigidity through enhancing
intramolecular D-A interaction.
To exploit efficient TADF emitters applied for constructing non-doped OLEDs, the
energy levels of HOMO/LUMO should match with the adjacent layers to accelerate
the charge injection and transporting. For the sake of getting the frontier orbital
energy levels, the electrochemical behaviors of DTPA-DTM and DTPA-DDTM were
measured using cyclic voltammetry. As shown in Fig. S6, The HOMO energy levels
of DTPA-DTM and DTPA-DDTM were estimated to be 5.09 eV and 5.10 eV,
respectively, according to the onset potentials. The LUMO energy levels were found
to be 2.39 eV and 2.55 eV for DTPA-DTM and DTPA-DDTM, respectively, which
were calculated from the HOMO and optical band gap (Eg).
Fig. 6 TGA (a) and DSC (b) curves of DTPA-DTM and DTPA-DDTM at a heating rate of 10 ℃ min-1 under
nitrogen.
Table 2 Photophysical rate constants of DTPA-DTM and DTPA-DDTM in neat films at room temperature.
푘푟, 푆a
푘푛푟, 푆b
푘퐼푆퐶c
푘푅퐼푆퐶d
Compound
7
-1
7
-1
7
-1
5 -1
[
10 s ]
[10 s ]
[10 s ]
[10 s ]
DTPA-DTM
1.99
2.10
3.16
1.37
4.37
2.05
6.5
6.7
DTPA-DDTM
a
b
c
Rate constant of fluorescence radiative transition. Rate constant of non-radiative transition. Rate constant of
d
intersystem crossing (ISC) process. Rate constant of reverse intersystem crossing (RISC) process.

Journal of Materials Chemistry C
Page 14 of 23
View Article Online
DOI: 10.1039/C9TC02467K
Electroluminescent properties
On the basis of the high PLQY and weak concentration quenching in solid state of
the designed TADF emitters, non-doped OLEDs were fabricated to evaluate the EL
properties. The device configuration was indium tin oxide (ITO)/HATCN (5
nm)/TAPC (30 nm)/EML (35 nm)/TmPyPB (40 nm)/LiF (1 nm)/Al (100 nm). In this
architecture, HATCN was used as hole-injection layer (HIL), TAPC acted as hole
transporting layer (HTL). TmPyPB was served as electron transporting layer (ETL)
due to its high triplet energy of 2.8 eV, which could prevent the transfer of triplet
exciton from EML to ETL. DTPA-DTM and DTPA-DDTM were used independently
as the emitting layers.
The energy diagrams of the device, EL spectra, current density-voltage-luminance
(J-V-L) and external quantum efficiency-luminance (EQE-L) characteristics were
displayed in Fig. 7. The device performance was summarized in Table 3. The devices
based on DTPA-DTM and DTPA-DDTM emitted solely from the EML, indicating
the effective charge recombination process in emitting layer without any energy
leakage to the nearby layers. The device using DTPA-DTM as emitter (device 1)
exhibited green EL emission with the maximum peak at 494 nm and Commission
Internationalde I’Eclairage coordinates at (0.21, 0.42). The device employed
DTPA-DDTM as emitter (device 2) exhibited yellow EL emission with the maximum
peak at 555 nm and Commission Internationalde I’Eclairage coordinates at (0.41,
0
8
.55). The device based on DTPA-DDTM as emitter showed a maximum EQE of
.2% and a maximum current efficiency of 25.6 cd/A, which was higher than that of
DTPA-DTM based device (4.4%, 9.7 cd/A). The improved performance of the device
based on DTPA-DDTM can be attributed to its relative higher PLQY and reduced
concentration quenching in solid state. The doped devices of these two emitters were
also fabricated in the mCP host material with high triplet energy (T = 2.9 eV). The
1
doping concentration was chosen with 30 wt% which displayed the highest PL
quantum yields in doped films among the doping concentration from 10% to 40%. As
shown in Fig. S9, the nearly identical EL spectra of doped device based on

Page 15 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
DTPA-DTM (Device 3) and DTPA-DDTM (Device 4) with their PL spectra which
suggesting the valid energy transfer from the mCP host to the emitters. The doped
device based on DTPA-DDTM achieved a maximum current efficiency (LE) and
external quantum efficiency (EQE) of 42.2 cd/A and 13.6%, respectively. The doped
devices shown better performances than the non-doped ones, which was similar with
the devices based on the emitter with TADF and AIE features reported previously.38,
3
9, 54
These results demonstrate the great potential of TADF and AIE materials
employed combined charge transfer pathways as the candidate of fabricating efficient
OLEDs.
Table 3 Electroluminescence characteristics of the devices.
λema
Vonb
Lmax
CIEc
(x,y)
CE
EQE
[%]
PE
Device
-1
[cd m-1]
[lm W-1]
[
nm]
494
555
489
540
[V]
[Cd A ]
Device 1
Device 2
Device 3
Device 4
3.8
3.9
3.7
9.7
2736
3432
4332
4788
4.4
8.2
7.1
6.3
(0.21, 0.42)
(0.41, 0.55)
(0.18, 0.39)
(0.36, 0.59)
25.6
15.2
11.8
28.2
15.6
3.8
42.2
13.6
a
b
-2
c
The maximum emission recorded at 5 V. Turn-on voltage measured at 1 cd m . Commission International de
I’Eclairage coordinates at 5 V.
Fig. 7 (a) Energy diagram of the materials used in the non-doped devices; (b) normalized EL spectral; (c) current
density-voltage-luminance (J-V-L) curves; (d) EQE versus luminance curves.
Conclusion

Journal of Materials Chemistry C
Page 16 of 23
View Article Online
DOI: 10.1039/C9TC02467K
In summary, two novel emitters simultaneously displayed TADF and AIE features
were designed and synthesized where change was transferred through the covalent
bond and through space simultaneously for efficient non-doped OLEDs. Benefiting
from the highly twist structure and enhanced degree of change transfer interactions
through introducing dual functional acceptor fragments, the PLQYs of DTPA-DDTM
in solid state were improved obviously compared with DTPA-DTM. By adopting the
strategy of combined charge transfer pathways, the small E and high radiative
st
efficiency were achieved at the same time. The non-doped OLEDs employed
DTPA-DDTM as emitter achieving the maximum current efficiency (LE) and external
quantum efficiency (EQE) of 25.6 cd/A and 8.2%, respectively. The strategy of
combing change transfer pathways opened up the possibility for developing novel
efficient TADF materials used for non-doped OLEDs.
Experimental
General information
All experimental materials and solvents were obtained from commercial approach
1
13
without any further purification if not particularly mentioned. H NMR and C NMR
spectra were performed on a Bruker Advance 600 MHz using DMSO-d6 and CDCl3
as solvents at room temperature. Single crystal X-ray diffraction intensity data were
collected at 193 K on Bruker D8 VENTURE PHOTON II system equipped with a
Liquid Metal source MetalJet ( Ga Kα, λ = 1.34139 Å) and a Helios Multi-layer Optic
monochromator. Low resolution mass spectra were recorded on a LC-MS (Agilent
1
260, Agilent Technologies), high resolution mass spectra were measured on
matrix-assisted laser desorptionionization time-of-flight mass spectrometry
MALDI-TOF-MS) using BRUKER DALTONICS instrument and
(
a
a-cyanohydroxycinnamic acid was selected as a matrix. UV-Vis absorption spectra
were measured on UV-2600 (Shimadzu Corporation) and photoluminescence
emission spectra were obtained from Fluoromax-4 (Horiba Jobin Yvon Inc)
spectrophotometer. The solid and solution PL quantum efficiencies of the targeted

Page 17 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
product were measured using an integrating sphere under nitrogen at room
temperature. Thermo gravimetric analysis (TGA) was performed with Netzsch
simultaneous thermal analyzer (STA) system (STA409 PC) under a dry nitrogen gas
-1
flow at a heating rate of 10℃ min . Differential scanning calorimetry (DSC) curves
were measured using a Netzsch instrument (TA, Netzsch). Cyclic voltammogram was
performed in CH Cl
solution (10-3 M) with tetrabutylammonium
hexafluorophosphate (0.1 M) as supporting electrolyte and ferrocene as the internal
2
2
-1
standard at a scant rate of 100 mV s on CHI750C voltammetric analyzer. A platinum
plate, silver wire and aplatinum wire were used as the working, reference and counter
electrode, respectively.
Device fabrication and measurements
Prior to use, the glass substrates were coated by indium tin oxide (ITO) with sheet
resistance of 15  per square and then cleaned in ultrasonic bath with deionized
water, acetone and ethanol for 15 minutes in sequence. Then the substrates were
treated with UV-ozone for 20 minutes. Organic layers were deposited into the
-4
ITO-coated substances when the pressure reached ~4×10 Pa in vacuum chamber.
−
1
The deposition rates of HATCN, organic materials, LiF and Al were 2 Å s , 1~2 Å
−
1
−1
−1
−2
s , 0.1 Å s and 6 Å s , respectively. The emission area was 3×3 mm controlled
through a shadow mask. All the tests were performed at room temperature in ambient
condition. Current density and luminance versus driving voltage curves and
electroluminescent spectra were measured by Keithley2400s Source Meter and Photo
Research PR 655 spectrophotometer. External quantum efficiencies of the devices
were calculated assuming a Lambertian emission distribution.
Materials
2
.3.1 Synthesis of dibenzo[b,d]thiophen-2-yl(2,5-dibromophenyl)methanone
(DBr-DTM)
A mixture of 2, 5-dibromobenzoic acid (1.5 g, 5.36 mmol) and thionyl chloride (15

Journal of Materials Chemistry C
Page 18 of 23
View Article Online
DOI: 10.1039/C9TC02467K
mL) was refluxed for 3 h. Removing the excess thionyl chloride under vacuum to give
2
6
,5-dibromobenzoyl chloride as a yellow crystalline solid. To a solution of
-bromonicotinoyl chloride and dibenzothiophene (0.99 g, 5.36 mmol) in dry
dichloromethane (30 ml), aluminum trichloride (0.85 g, 6.4 mmol) was added slowly
at 0ºC. The reaction mixture was stirred at room temperature for 6 h and reflux for 3
h. Then, the reaction was quenched by pouring into 200 mL ice-HCl solution. The
mixture was extracted with dichloromethane. The combined organic phase was
washed 3 times with water and dried over anhydrous MgSO . The solvent was
4
removed under reduced pressure and the residue was purified on a silica gel column
using petroleum ether/dichloromethane mixture (4:1, v/v) as eluent to afford the
1
product as white powder in 84% yield. H NMR (600 MHz, DMSO) δ [ppm]: 8.74 (s,
1
H), 8.52 (d, J = 7.8 Hz, 1H), 8.23 (d, J = 8.4 Hz, 1H), 8.11 (d, J = 7.8 Hz, 1H), 7.85
(d, J = 1.8 Hz, 1H), 7.81 (dd, J = 8.4, 1.4 Hz, 1H), 7.76-7.73 (m, 2H), 7.60 (t, J = 7.5
1
3
Hz, 1H), 7.55 (t, J = 7.4 Hz, 1H). C NMR (150 MHz, DMSO) δ [ppm]: 193.86,
1
1
45.52, 142.82, 139.47, 135.87, 135.34, 134.96, 134.89, 132.52, 131.92, 128.45,
28.31, 125.79, 124.18, 123.80, 123.75, 123.22, 121.65, 118.13. MS (MALDI-TOF)
[m/z]: calcd for C H Br OS, 445.88; found, 446.96.
19 10 2
2
.3.2
Synthesis
of
(2,5-dibromo-1,4-phenylene)bis(dibenzo[b,d]thiophen-2-ylmethanone) (DBr-DDTM)
DBr-DDTM was synthesized according to the same procedure with DBr-DTM as
1
white solid in 80% yield. H NMR (600 MHz, DMSO) δ [ppm]: 8.90 (s, 2H), 8.66 (d,
J = 7.2 Hz, 2H), 8.31 (d, J = 8.4 Hz, 2H), 8.14 (d, J = 7.3 Hz, 2H), 8.08 (s, 2H), 8.03
1
3
(
dd, J = 8.4, 1.1 Hz, 2H), 7.63 (dt, J = 20.4, 6.8 Hz, 4H). C NMR (150 MHz, CDCl )
3
δ [ppm]: 193.54, 146.33, 143.53, 139.72, 136.08, 134.95, 133.22, 131.75, 127.94,
27.81, 125.21, 123.66, 123.24, 123.01, 122.25, 118.78. MS (MALDI-TOF) [m/z]:
calcd for C H Br O S , 655.89; found, 656.17.
1
3
2
16
2 2 2
2
.3.3
4,4''-bis(diphenylamino)-[1,1':4',1''-terphenyl]-2'-yl)(dibenzo[b,d]thiophen-2-yl)meth
anone (DTPA-DTM)
synthesis
of
(

Page 19 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
DBr-DTM (500 mg, 1.12 mmol), (4-(diphenylamino)phenyl)boronic acid (0.81 g,
2
.8
mmol),
potassium
carbonate
(0.28
g,
2
mmol),
terakis(triphenylphosphine)palladium (0.16 g, 0.14 mmol) were dissolved in a mixture
solution of toluene (15 ml), ethanol (10 ml), water (10 ml) and refluxed under
nitrogen at 100℃ for 12 h. Then, the reaction was extracted with dichloromethane
and washed with water. The organic layer was dried over anhydrous MgSO and the
4
residue was purified on a silica gel column using petroleum ether/dichloromethane
1
mixture (3:1, v/v) as eluent to afford the product as green powder in 70% yield. H
NMR (600 MHz, DMSO) δ [ppm]: 8.43 (s, 1H), 8.32 (t, J = 8.0 Hz, 1H), 8.10 (dd, J =
7
2
.9, 4.5 Hz, 1H), 7.98 (t, J = 8.0 Hz, 2H), 7.88 (d, J = 1.6 Hz, 1H), 7.72 (d, J = 7.1 Hz,
H), 7.67 – 7.49 (m, 4H), 7.33 (t, J = 7.8 Hz, 4H), 7.14 (t, J = 8.7 Hz, 2H), 7.10 – 7.04
(m, 8H), 6.97 (dt, J = 27.2, 7.8 Hz, 4H), 6.88 (dd, J = 13.2, 6.0 Hz, 2H), 6.65 (dd, J =
1
3
1
1
1
1
9.9, 8.3 Hz, 2H), 6.54 (t, J = 6.3 Hz, 4H). C NMR (150 MHz, CDCl ) δ [ppm]:
3
98.75, 147.65, 147.54, 147.28, 147.04, 143.98, 139.27, 135.14, 129.87, 129.32,
29.03, 128.77, 127.73, 127.52, 124.95, 124.58, 124.02, 123.95, 123.71, 123.42,
23.12, 122.92, 122.76, 122.06,121.96. MS (MALDI-TOF) [m/z]: calcd for
C H N OS, 774.27; found, 774.36130.
5
4
37
2
2
.3.4
synthesis
of
(4,4''-bis(diphenylamino)-[1,1':4',1''-terphenyl]-2',5'-diyl)bis(dibenzo[b,d]thiophen-2-
ylmethanone) (DTPA-DDTM)
DTPA-DDTM was synthesized according to the same procedure with DBr-DTM as
1
yellow power in 89% yield. H NMR (600 MHz, CDCl ) δ [ppm]: 8.48 (s, 2H),
3
8
7
4
.20-8.16 (m, 2H), 7.90 (dd, J = 6.3, 2.3 Hz, 2H), 7.86 (s, 2H), 7.78-7.73 (m, 4H),
.56-7.51 (m, 4H), 7.25-7.21 (m, 4H), 6.98 (t, J = 7.9 Hz, 8H), 6.88 (t, J = 7.4 Hz,
1
3
H), 6.78 (d, J = 8.7 Hz, 4H), 6.68 (d, J = 7.5 Hz, 8H). C NMR (150 MHz, CDCl ) δ
3
[ppm]: 198.16, 147.50, 147.19, 144.44, 140.73, 139.71, 139.55,135.23, 135.13,
1
1
33.55, 132.78, 130.38, 129.93, 129.08, 127.98, 127.50, 125.08, 124.18, 123.44,
23.31, 122.95, 122.94, 122.28, 122.09. MS (MALDI-TOF) [m/z]: calcd for
C H N O S , 984.28; found, 985.41048.
6
4 44 2 2 2

Journal of Materials Chemistry C
Page 20 of 23
View Article Online
DOI: 10.1039/C9TC02467K
Conflicts of interest
There are no conflicts to declare.
Acknowledgements
The authors gratefully acknowledge the supporting from the Ministry of Science
and Technology key research and development plan (2018YFF0215204) and the
Science and Technology Achievements Transformation Special Fund of Jiangsu
Province (BA2017035).
References
1
2
3
4
5
6
.
.
.
.
.
.
X. Cai and S.-J. Su, Adv. Funct. Mater., 2018, 28, 1802558.
J. H. Kim, J. H. Yun and J. Y. Lee, Adv. Optical Mater., 2018, 6, 1800255.
K. Goushi, K. Yoshida, K. Sato and C. Adachi, Adachi, Nat. Photonics, 2012, 6, 253-258.
Y. Im, M. Kim, Y. J. Cho, J.-A. Seo, K. S. Yook and J. Y. Lee, Chem. Mater., 2017, 29, 1946-1963.
H. Uoyama, K. Goushi, K. Shizu, H. Nomura and C. Adachi, Nature, 2012, 492, 234-238.
H. Nakanotani, T. Higuchi, T. Furukawa, K. Masui, K. Morimoto, M. Numata, H. Tanaka, Y.
Sagara, T. Yasuda and C. Adachi, Nature Commun., 2014, 5, 4016.
7
8
9
1
1
1
1
1
.
Q. Wei, N. Fei, A. Islam, T. Lei, L. Hong, R. Peng, X. Fan, L. Chen, P. Gao and Z. Ge, Adv. Optical
Mater., 2018, 6, 1800512.
.
K. Wu, T. Zhang, Z. Wang, L. Wang, L. Zhan, S. Gong, C. Zhong, Z. H. Lu, S. Zhang and C. Yang,
J. Am. Chem. Soc., 2018, 140, 8877-8886.
.
Q. Zhang, J. Li, K. Shizu, S. Huang, S. Hirata, H. Miyazaki and C. Adachi, J. Am. Chem. Soc.,
2
012, 134, 14706-14709.
0.
1.
2.
3.
4.
P. Rajamalli, N. Senthilkumar, P. Y. Huang, C. C. Ren-Wu, H. W. Lin and C. H. Cheng, J. Am.
Chem. Soc., 2017, 139, 10948-10951.
M. Kim, S. J. Yoon, S. H. Han, R. Ansari, J. Kieffer, J. Y. Lee and J. Kim, Chem. – Eur. J., 2019, 25,
1
829-1834.
X. Cai, D. Chen, K. Gao, L. Gan, Q. Yin, Z. Qiao, Z. Chen, X. Jiang and S.-J. Su, Adv. Funct.
Mater., 2018, 28, 1704927..
W. Zeng, H. Y. Lai, W. K. Lee, M. Jiao, Y. J. Shiu, C. Zhong, S. Gong, T. Zhou, G. Xie, M. Sarma,
K. T. Wong, C. C. Wu and C. Yang, Adv. Mater., 2018, 30, 1704961..
Z.-P. Chen, D.-Q. Wang, M. Zhang, K. Wang, Y.-Z. Shi, J.-X. Chen, W.-W. Tao, C.-J. Zheng, S.-L.
Tao and X.-H. Zhang, Adv. Optical Mater., 2018, 6, 1800935.
1
1
1
1
5.
6.
7.
8.
C. Y. Chan, M. Tanaka, H. Nakanotani and C. Adachi, Nature commun., 2018, 9, 5036.
H.-J. Park, S. H. Han, J. Y. Lee, H. Han and E.-G. Kim, Chem. Mater., 2018, 30, 3215-3222.
S. Y. Lee, T. Yasuda, I. S. Park and C. Adachi, Dalton Trans., 2015, 44, 8356.
J. X. Chen, K. Wang, C. J. Zheng, M. Zhang, Y. Z. Shi, S. L. Tao, H. Lin, W. Liu, W. W. Tao, X. M.

Page 21 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
Ou and X. H. Zhang, Adv. Sci., 2018, 5, 1800436.
1
9.
X. Wang, S. Wang, J. Lv, S. Shao, L. Wang, X. Jing and F. Wang, Chem. Sci., 2019, 10,
915-2923.
2
2
2
0.
1.
S. Shao, J. Hu, X. Wang, L. Wang, X. Jing and F. Wang, J. Am. Chem. Soc., 2016, 138, 628-634.
P. Rajamalli, N. Senthilkumar, P. Gandeepan, P. Y. Huang, M. J. Huang, C. Z. Ren-Wu, C. Y.
Yang, M. J. Chiu, L. K. Chu, H. W. Lin and C. H. Cheng, J. Am. Chem. Soc., 2016, 138, 628-634.
H. Tsujimoto, D. G. Ha, G. Markopoulos, H. S. Chae, M. A. Baldo and T. M. Swager, J. Am.
Chem. Soc., 2017, 139, 4894-4900.
2
2
2
2.
3.
4.
J.-T. Ye, L. Wang, H.-Q. Wang, X.-M. Pan, H.-M. Xie and Y.-Q. Qiu, J. Phys. Chem. C, 2018, 122,
1
8850-18859.
X. L. Chen, J. H. Jia, R. Yu, J. Z. Liao, M. X. Yang and C. Z. Lu, Angew. Chem. Int. Ed., 2017, 56,
5006-15009.
1
2
2
2
5.
6.
7.
J. Lee, N. Aizawa and T. Yasuda, Chem. Mater., 2017, 29, 8012-8020.
M. Li, F. Peng, L. Ying and J. Xu, J. Mater. Chem. C, 2019, 7, 3553-3559.
Y. Li, T. Chen, M. Huang, Y. Gu, S. Gong, G. Xie and C. Yang, J. Mater. Chem. C, 2017, 5,
3
480-3487.
2
2
8.
9.
L. Yu, Z. Wu, G. Xie, W. Zeng, D. Ma and C. Yang, Chem. Sci., 2018, 9, 1385-1391.
W. L. Tsai, M. H. Huang, W. K. Lee, Y. J. Hsu, K. C. Pan, Y. H. Huang, H. C. Ting, M. Sarma, Y. Y.
Ho, H. C. Hu, C. C. Chen, M. T. Lee, K. T. Wong and C. C. Wu, Chem. Commun., 2015, 51,
1
3662-13665.
K. Albrecht, K. Matsuoka, K. Fujita and K. Yamamoto, Angew. Chem. Int. Ed., 2015, 54,
677-5682.
3
3
0.
1.
5
J. Huang, Z. Xu, Z. Cai, J. Guo, J. Guo, P. Shen, Z. Wang, Z. Zhao, D. Ma and B. Z. Tang, J.
Mater. Chem. C, 2019, 7, 330-339.
3
3
2.
3.
J. Guo, Z. Zhao and B. Z. Tang, Adv. Optical Mater., 2018, 6, 1800264.
L. Yu, Z. Wu, G. Xie, C. Zhong, Z. Zhu, D. Ma and C. Yang, Chem. Commun., 2018, 54,
1
379-1382.
J. Li, R. Zhang, Z. Wang, B. Zhao, J. Xie, F. Zhang, H. Wang and K. Guo, Adv. Optical Mater.,
018, 6, 1701256.
3
3
3
3
3
3
4
4
4
4.
5.
6.
7.
8.
9.
0.
1.
2.
2
Y. Zhao, W. Wang, C. Gui, L. Fang, X. Zhang, S. Wang, S. Chen, H. Shi and B. Z. Tang, J. Mater.
Chem. C, 2018, 6, 2873-2881.
G. Grybauskaite-Kaminskiene, D. Volyniuk, V. Mimaite, O. Bezvikonnyi, A. Bucinskas, G.
Bagdziunas and J. V. Grazulevicius, Chem. – Eur. J., 2018, 24, 9581-9591.
J. Guo, J. Fan, L. Lin, J. Zeng, H. Liu, C.-K. Wang, Z. Zhao and B. Z. Tang, Adv Sci., 2018, 6,
1
801629.
J. Guo, X.-L. Li, H. Nie, W. Luo, S. Gan, S. Hu, R. Hu, A. Qin, Z. Zhao, S.-J. Su and B. Z. Tang,
Adv. Funct. Mater., 2017, 27, 1606458.
J. Huang, H. Nie, J. Zeng, Z. Zhuang, S. Gan, Y. Cai, J. Guo, S. J. Su, Z. Zhao and B. Z. Tang,
Angew. Chem. Int. Ed., 2017, 56, 12971-12976.
H. Liu, J. Zeng, J. Guo, H. Nie, Z. Zhao and B. Z. Tang, Angew. Chem. Int. Ed., 2018, 57,
9
290-9294.
S. Xu, T. Liu, Y. Mu, Y. F. Wang, Z. Chi, C. C. Lo, S. Liu, Y. Zhang, A. Lien and J. Xu, Angew.
Chem. Int. Ed.,2015, 54, 874-878.
N. Aizawa, C.-J. Tsou, I. S. Park and T. Yasuda, Polymer Journal, 2017, 49, 197-202.

Journal of Materials Chemistry C
Page 22 of 23
View Article Online
4
4
3.
4.
R. Furue, T. Nishimoto, I. S. Park, J. Lee and T. Yasuda, Angew. Chem. Int. Ed., 2016, 55,
DOI: 10.1039/C9TC02467K
7
171-7175.
X. Chen, Z. Yang, Z. Xie, J. Zhao, Z. Yang, Y. Zhang, M. P. Aldred and Z. Chi, Mater. Chem.
Front.,
2
018, 2, 1017
J. Zhao, X. Chen, Z. Yang, T. Liu, Z. Yang, Y. Zhang, J. Xu and Z. Chi, J. Phys. Chem. C., 2019,
23, 1015−1020.
4
5.
1
4
4
6.
7.
B. Li, L. Zhou, H. Cheng, Q. Huang, J. Lan, L. Zhou and J. You, Chem. Sci., 2018, 9, 1213-1220.
X. Tang, Q. Bai, Q. Peng, Y. Gao, J. Li, Y. Liu, L. Yao, P. Lu, B. Yang and Y. Ma, Chem. Mater.,
2
015, 27, 7050-7057.
X. Ban, A. Zhu, T. Zhang, Z. Tong, W. Jiang and Y. Sun, Appl. Mater. Interfaces, 2017, 9,
1900-21908.
4
4
5
5
5
5
5
8.
9.
0.
1.
2.
3.
4.
2
C. H. Ryoo, I. Cho, J. Han, J. H. Yang, J. E. Kwon, S. Kim, H. Jeong, C. Lee and S. Y. Park, Appl.
Mater. Interfaces, 2017, 9, 41413-41420.
K. Wang, C. J. Zheng, W. Liu, K. Liang, Y. Z. Shi, S. L. Tao, C. S. Lee, X. M. Ou and X. H. Zhang,
Adv. Mater., 2017, 29, 1701476.
H. Zhao, Z. Wang, X. Cai, K. Liu, Z. He, X. Liu, Y. Cao and S.-J. Su, Mater. Chem. Front., 2017, 1,
2
039-2046.
T. Ohsawa, H. Sasabe, T. Watanabe, K. Nakao, R. Komatsu, Y. Hayashi, Y. Hayasaka and J.
Kido, Adv. Optical Mater., 2019, 7, 1801282.
Y. Chen, S. Wang, X. Wu, Y. Xu, H. Li, Y. Liu, H. Tong and L. Wang, J. Mater. Chem. C., 2018, 6,
1
2503-12508.
S. Y. Park, S. Choi, G. E. Park, H. J. Kim, C. Lee, J. S. Moon, S. W. Kim, S. Park, J. H. Kwon, M. J.
Cho and D. H. Choi, Appl. Mater. Interfaces, 2018, 10, 14966-14977.

Page 23 of 23
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC02467K
Achieving combined charge transfer pathways in novel thermally activated delayed
fluorescence emitters with aggregation-induced emission features.