Structural Insight into Aggregation and Orientation of TPD-Based Conjugated Polymers for Efficient Charge-Transporting Properties

Article abstract of DOI:10.1021/acs.chemmater.8b04605

In this study, we obtained a new structural insight into the charge-transporting properties in TPD-based polymers that cannot be solely explained in terms of the type of orientation. We synthesized two types of copolymers comprising mono-TPD or bis-TPD as the accepting unit. Although the planarity and energy levels are similar with the mono-TPD unit, the aggregation state is quite different, and the X-aggregation tendency seems to be stronger when the bis-TPD unit is incorporated. In the case of TPD1, an effective π-πorbital overlap is found to originate from the H-aggregates, and 3D charge transport pathways are formed with a bimodal orientation of edge-on and face-on, resulting in an efficient charge transportation (1.84 cm²·V^-1·s^-1 of hole and 0.31 cm²·V^-1·s^-1 of electron). In contrast, despite the well-aligned edge-on orientation of TPD2, it exhibited a relatively very low mobility and splitted emission characteristics in photoluminescence spectra because of the tilted intermolecular stacking pattern with an X-shape (0.015 cm²·V^-1·s^-1 for hole and 0.16 cm²·V^-1·s^-1 for electron). An overall characterization of the semiconducting polymers was performed, and it was found that the type of aggregation in the final thin films, such as H- or X-aggregation, is indeed important and perhaps more important than the orientation to obtain polymers with a high charge carrier mobility.

Full text of DOI:10.1021/acs.chemmater.8b04605

Subscriber access provided by Bibliothèque de l'Université Paris-Sud
Article
Structural Insight into Aggregation and Orientation of TPD-based
Conjugated Polymers for Efficient Charge Transporting Properties
Dae-Hee Lim, Yeon-Ju Kim, Yeong-A Kim, Kyoungtae Hwang, Jong-Jin Park, and Dong-Yu Kim
Chem. Mater., Just Accepted Manuscript • DOI: 10.1021/acs.chemmater.8b04605 • Publication Date (Web): 03 Apr 2019
Downloaded from http://pubs.acs.org on April 4, 2019
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a service to the research community to expedite the dissemination
of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in
full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully
peer reviewed, but should not be considered the official version of record. They are citable by the
Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore,
the “Just Accepted” Web site may not include all articles that will be published in the journal. After
a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web
site and published as an ASAP article. Note that technical editing may introduce minor changes
to the manuscript text and/or graphics which could affect content, and all legal disclaimers and
ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or
consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W.,
Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 13
Chemistry of Materials
1
2
3
4
5
6
7
8
9
Structural Insight into Aggregation and Orientation of TPD-based
Conjugated Polymers for Efficient Charge Transporting Properties
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Dae-Hee Lim, §† Yeon-Ju Kim, §† Yeong-A Kim, ‡ Kyoungtae Hwang, † Jong-Jin Park † and Dong-
Yu Kim *†
School of Materials Science and Engineering, Heeger Center for Advanced Materials (HCAM),
Gwangju Institute of Science and Technology (GIST)
ABSTRACT: In this study, we obtained new structural insight into the charge transporting properties in TPD-based polymers that
cannot be solely explained in terms of the type of orientation. We synthesized two types of copolymers comprising mono-TPD or
bis-TPD as the accepting unit. While the planarity and energy levels are similar with the mono-TPD unit, the aggregation state is
quite different, and the X-aggregation tendency seems to be stronger when the bis-TPD unit is incorporated. In the case of TPD1, an
effective π–π orbital overlap is found to originate from the H-aggregates, and 3D charge transport pathways are formed with a bimodal
orientation of edge-on and face-on, resulting in an efficient charge transportation (1.84 cm2 V−1 s−1 of hole and 0.31 cm2 V−1 s−1 of
electron). In contrast, despite the well-aligned edge-on orientation of TPD2, it exhibited a relatively very low mobility and splitted-
emission characteristics in photoluminescence spectra because of the tilted inter-molecular stacking pattern with an X-shape (0.015
cm2 V−1 s−1 for hole and 0.16 cm2 V−1 s−1 for electron). An overall characterization of the semiconducting polymers was performed,
and it was found that the type of aggregation in the final thin films, such as H- or X-aggregation, is indeed important and perhaps
more important than the orientation to obtain polymers with a high charge carrier mobility.
INTRODUCTION
have been mainly explained by the direction of orientation of
molecules until now. However, for higher performance
enhancement, it is necessary to analyze the relationship
between in-depth molecular organization structure and their
transporting properties, and to derive structural interpretation
and further design direction.
The development of organic semiconductors is being
pursued with great interest, as they are promising materials for
organic electronics owing to their unique advantages such as
low weight, flexibility on plastic substrates, facile
processability, and chemical tunability.1-3 To be applied to
Semiconducting molecules can have a pre-aggregated state
in the solution prior to forming orientation states. The
microstructure control of pre-aggregation in the solution can
make molecular alignment and orientation more effectively lead
to enhanced device performance.12 The aggregation state of the
molecules has been studied as a way to enhance the alignment
in thin films.13, 14 On the other hand, the aggregation type in
thin-film states has not been fully elucidated, especially in
semiconducting polymer films. To the best of our knowledge,
this is the first report that investigates the change in the
aggregation type in thin films by varying the polymer structure
and clarifies the relationship between the aggregation type and
charge transporting properties. From a structural viewpoint,
understanding the type of aggregation could be a key factor in
interpreting the various characteristics that cannot be explained
by orientation type alone.
In this study, we synthesized two copolymers of different
molecular stacking types: one with mono-TPD and another with
bis-TPD as the accepting unit and investigated relationship
between the aggregation type and charge-transporting
properties. As an electron-deficient building block due to the
presence of an imide group, thieno[3,4-c]pyrrole-4,6-dione
(mono-TPD) was used which has a solubilizing influence on the
polymer because of the alkyl functionality on the nitrogen atom.
The mono-TPD unit has an axi-symmetric and fused structure,
ubiquitous
plastic
electronics
including
flexible/stretchable/wearable applications, more detailed
structural insight into the organic semiconducting materials
with high charge carrier mobility needs to be obtained.
For achieving high performance of organic electronics,
remarkable progress has been made in the development of
semiconducting materials, and several research groups have
reported field-effect mobilities exceeding 10 cm2 V-1 s-1.4-7 In
most of these high-performance materials, edge-on orientation
models predominate. These orientation features are well known
for achieving high-performance on charge carrier transporting
properties by allowing the intermolecular interactions with
reduced π-π stacking distance parallel to the direction of the
channel current flow. However, in recent studies, bimodal
polymer films containing mixtures of both edge-on and face-on
orientations also exhibited a surprisingly high-performance
improvement over the unimodal edge-on orientation polymer
films.8-11 Three-dimensional (3D) charge carrier conduction
channels are formed within the molecular packing directions in
both parallel and perpendicular orientations. Once these
pathways are formed along with the channel directions, the
charge transport is facilitated by opening up the alternative
transporting routes. In this way, charge transporting properties
ACS Paragon Plus Environment

Chemistry of Materials
which could be beneficial for electron delocalization in
Page 2 of 13
1
2
3
4
5
6
7
8
conjugated polymer backbones, thereby encouraging electronic
orbital hybridization.15-22 On the other hand, bi-thieno[3,4-c]-
pyrrole-4,6-dione (bis-TPD) with intramolecular S···O
interactions has an extended π-conjugation length because of
the enhanced planarity and reduced conformational disorder.
While the planarity and energy levels are similar with the mono-
TPD unit, introducing a bis-TPD building block to the polymer
backbone can have a different effect on the molecular stacking
pattern via increasing the TPD monomer unit density.23-27 An
overall characterization of the polymers was performed, and it
was found that the type of aggregation and orientation of the
polymers in the final films, such as H-, J-, and X- aggregations,
are indeed important to obtain polymers with high charge
carrier mobility.
Scheme 1. The synthetic procedures of the monomers
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
RESULTS AND DISCUSSION
Material Synthesis and Characterization
The synthetic routes of the monomers toward the target
structures of TPD1 and TPD2 are shown in Scheme 1; the three
monomers,
namely
mono-TPD,
bis-TPD,
and
thienylenevinylene, were prepared based on previous studies.15,
Schem 2. Synthesis of the TPD-based polymers
23, 28, 29
The polymers were prepared via a still-polymerization
method.[29] As shown in Scheme 2, the dibrominated mono-
TPD and bis-TPD monomers were coupled with distannylated
thienylenevinylene monomers in the presence of 2 mol%
Pd2dba3 and 8 mol% P(o-tol)3 in anhydrous toluene. The
solubilities of the two monomer units of mono-TPD and bis-
TPD were different. Therefore, we controlled the reaction
temperature and reaction time for each polymer. The synthetic
details of two different polymerization conditions are described
in the Supporting Information section. Table 1 lists the number
average molecular weight (Mn), weight average molecular
weight (Mw), and polydispersity (ĐM) of the polymers. The
thermal properties of the two polymers were investigated by
thermogravimetry analysis (TGA) and differential scanning
calorimetry (DSC), as shown in Figures S1 and S2. For the two
polymers, the thermal decomposition temperature (Td) with 5%
weight loss from TGA analysis was measured to be over 400 °C.
This shows that the two polymers exhibited sufficient thermal
stability for electron device applications. In the DSC analysis,
TPD1 and TPD2 did not exhibit any thermal transition, neither
endothermic (Tm) nor exothermic (Tc) transition, owing to their
rigid and coplanar structural properties. In addition, all the
polymers exhibited low solubility in common organic solvents,
even when heated to 60 °C, especially TPD2. This was also
anticipated because the backbone structures of the two
polymers are rigid and planar.
Optical and Electrochemical Properties
In the thin film states of the two polymers, the HOMO and
LUMO energy levels were determined using cyclic
voltammetry (CV) measurements. Figure 2b shows the cyclic
voltammograms. In the case of TPD2 containing the bis-TPD
building block, the HOMO energy level is lower than that of
TPD1 because the electron deficient TPD building block is
introduced into the polymer backbone as the acceptor-acceptor
(A-A) unit. Figure 2c shows the HOMO energy level of each
polymer and the schematic of the energy band diagram with the
calculated optical bandgap.
UV-Vis absorption spectra were measured in toluene
solution and in the thin films of the two polymers to check the
pre-aggregation characteristic. Figures 1a show the absorption
spectra of toluene solutions and as- casted thin films. In TPD1,
Table 1. Intrinsic properties of TPD1 and TPD2 polymers
opt
ĐM
HOMOb /
eV
LUMOc /
eV
Eg /
a o
Polymers
Mn/g mol-1
Mw/g mol-1
Td / C
(Mw/Mn)
1.6
eV
TPD1
TPD2
14,803
9,648
24,196
26,710
410
408
-5.04
-5.23
3.39
3.58
1.65
1.65
2.8
a Decomposition temperature corresponding to 5% weight loss in N2 determined by TGA.
b HOMO energy level is calculated with Ferrocene half potential ~ - 4.8 eV
c LUMO energy level is calculated from HOMO level and optical band gap
ACS Paragon Plus Environment

Page 3 of 13
Chemistry of Materials
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 1 (a) Optical absorption spectra in toluene solution and as-casted film of TPD1 and TPD2.
(b) Cyclic voltammograms of two polymers and (c) their energy level diagrams.
absorption maxima (λmax) at 628 nm and strong shoulder
peaks are observed. These peaks exhibited very weak
blue shift between the solution state and the thin-film
state. In TPD2, absorption maxima exhibited in the same
wavelength region in both the solution and the thin film
states, showing neither hypsochromic and bathochromic
shift. In both polymers, there shows strong absorption
shoulder peak even in solution state, which suggest the
presence of pre-aggregations in the solution states
attributed from the strong intermolecular interactions.12
In many studies, the type of aggregation has been
explained in terms of the absorption peak shift, such as
the bathochromic shift and hypsochromic shift, when the
film is formed from the solution. Unfortunately, in this
study, we observed the very weak blue shift between the
solution and film in only TPD1 due to the strong pre-
aggregation caused by low solubility even in the solution
state. Nevertheless, interestingly, the absorption
coefficient is significantly greater at TPD1 (7.65 × 104
cm−1) than at TPD2 (2.71 × 104 cm−1).
Aggregation behaviors analyzed by absorption and emission
Figure 2. (a) Splitting energy in J- , H-, X- aggregates of dimer systems in the framework of exciton model. For
all types of aggregates the optically allowed transitions are indicated by the solid lines. UV-vis absorption spectra/
fluorescence emission spectra (left) with the corresponding schematic diagrams of energy levels (right) for (b)
TPD1 and (c) TPD2, respectively.
ACS Paragon Plus Environment

Chemistry of Materials
Page 4 of 13
1
2
3
4
5
6
7
8
9
The aggregation type, in conjunction with the
intermolecular rotation could be classified as X-
aggregation, the smaller slippage or smaller rotation
could be classified as H-aggregation.34, 38 However, in
contrast to H-aggregates, in all these cases, both twisted
sandwich and X-aggregates with a small angle between
adjacent molecules exhibit stronger PL emission because
of the reduced orbital overlap of adjacent stacking
molecules.
absorption peak shift, has usually been described by
analyzing the single-crystal patterns, which can be
identified directly.30-32 On the contrary, the change in the
aggregation type in the polymer thin-film state has not
been fully elucidated. According to Kasha et al., the sign
of the Coulomb coupling by aggregates has a direct
influence on the photophysical response.33 There are
some types of aggregates, namely H-, J-, X-aggregates,
twisted-sandwich and oblique, according to the transition
dipole stacking mode. Figure 2a shows the schematics
of their energy splitting diagrams.34 Based on this, we
describe the features of the aggregation type that changes
after thermal treatment in two polymers in the thin-film
state.
In the case of TPD1, as shown in Figure 2b, the
evidences that TPD1 has H-aggregate features are
revealed in both TPD1 films before and after thermal
treatment as follows: (i) In the absorption and PL
emission spectra, the peak position of the absorption
wavelength (A1) and that of the emission wavelength (0-
1) are different, and there is no (0-0) transition. This is
because the optically accessible state is located at the top
of the exciton band. In addition, in the ideal H-aggregates
comprising rigid molecules, the emission of the (0-0)
transition is optically forbidden. After the excitation into
the optically accessible state, the intraband relaxation
occurs much faster than the decay into the electronic
ground state. The parallel H-aggregates in molecular
stacking pattern showing face-to-face π-π interactions is
favorable for charge carrier transport.30-32 (ii) After the
thermal treatment, the intensity of the A1 is suppressed
with respect to A2. It was deduced from Spano’s model
that the H-aggregates are distinguished by the intensity
ratio of the A1 and A2 transitions.32 Accordingly, in the
intensity ratio of the transitions into the A1 and A2
manifolds, the A1 transition becomes weaker for the
strong coupling of the H-aggregates.35, 36 (iii) While the
absorption intensity is similar to TPD2, the emission
intensity of TPD1 is found to be significantly lower than
that of TPD2. (iv) The most predominant evidence that
can demonstrate H-aggregate properties of the TPD1
thin-film is the PL quenching observed after the thermal
treatment.37 Based on these phenomena in TPD1, it can
be deduced that the face-to-face H-aggregation stacking
features become more predominantly aligned, which can
be explained more in connection with the following
crystal patterns of 2D-GIWAXS.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(iii) The noticeable difference between TPD1 and TPD2
in terms of the optical properties is due to the fact that
significantly higher emission intensities were measured
in both TPD2 films before and after the thermal treatment.
This is not a characteristic of H-aggregates but can be
observed when the transition moment vectors form the
twisted or tilted states.38, 39 These features can be also
interpreted in more detail and are correlated with the 2D-
GIWAXS pattern analysis following Figure 3. (iv) In the
TPD2 thin films before and after the thermal treatment,
they exhibit different PL emission features. The
maximum emission peak is red-shifted to the lower
energy region than that before the thermal treatment, and
the single emission peak also changes to splitted-
emission. The existence of splitted-emission would
probably occur in the asymmetrically stacking moieties
as X-aggregates in the polymer backbone induced by
steric effects. These PL splitting phenomena seem to be
controllable by the aggregates state.40-43 However, the
information from the emission spectra is not sufficient to
obtain a complete structural insight into the aggregate
types. Therefore, an overall subsequent characterization
is needed to further elucidate whether these
characteristics are attributed to twisted sandwich-like
aggregates or to X-aggregates, which will be discussed
later.
Aggregates types correlated with crystallographic
patterns of 2D-GIWAXS
The crystallographic information from the 2D-
GIWAXS analysis will be described to support the
information of the optical spectra to further clarify the
aggregate types in the polymer thin-films. To induce a
highly aligned molecular order, the films were prepared
using a pre-aggregation solution and were fabricated
using the off-centered coating technique. These coating
method can induce effective polymer chain alignment in
one direction induced by the unidirectional shear force,
especially for the pre-aggregated conjugated polymer
solution.12 Figures 3a and 3c show the 2D-GIWAXS
images. Figures 3b, 3d and Table 2 show the 1D-
GIWAXS profiles for the in-plane and out-of-plane
directions.
In the case of TPD1, as shown in Figures 4a and 4b,
a bimodal orientation is verified both before and after the
thermal treatment, as follows: (i) The (h00) diffraction
peaks along the qxy and qz directions were in pristine film,
and their intensities increase following the thermal
treatment. The (h00) diffraction patterns consist of spot-
like shapes in each crystallographic plane. This means
that the TPD1 has a bimodal packing structure and
narrow orientation distributions in the thin films.44, 45 (ii)
A strong (010) diffraction was observed both in the in-
Unlike TPD1, TPD2 has different aggregate features
before and after the thermal treatment, as shown in
Figure 2c. In both conditions, the TPD2 thin films
predominantly shows the absorption features of H-
aggregates. However, the TPD2 thin film before the
thermal treatment is supposed to exhibit twisted
sandwich-like aggregates, and the sample after the
thermal treatment is considered to form X-aggregates:
TPD2 shows the same optical properties, as mentioned in
(i) and (ii), which were described as the evidences for
TPD1 having H-aggregates, indicating that TPD2 also
contains near-H-aggregate absorption characteristics.
According to previous studies for the aggregation, while
large intermolecular transition dipole slippage or large
ACS Paragon Plus Environment

Page 5 of 13
Chemistry of Materials
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 3. 2D-GIWAXS images of off-center coated films (a) TPD1 and (c) TPD2 with pristine (left) and after
thermal treatment at 300 oC (right). The corresponding 1D-GIWAXS profiles of out-of-plane (left) and in-plane
pattern (right) for (b) TPD1 and (d) TPD2.
plane and out-of-plane directions showing face-to-face π-
π interactions, which are beneficial for 3D charge
transport pathway. The formation of highly efficient
pathways is found to originate from the H-aggregates,
which are favorable to form π-π interaction by enhancing
the orbital overlap at the molecular level. These are
expected to show a synergetic effect when the pathways
formed by H-aggregation are oriented in both in-plane
and out-of-plane directions.
stacking of the X-shape would have slightly tilted angles.
Moreover, the (h00) diffraction of the GIWAXS patterns
is in the arc form, indicating a broad distribution
orientation of the molecular alignment; this could be
another evidence for X-aggregates, even though it is not
directly linked with X-aggregate features. The X-
aggregate formations are induced by the complicated
structural steric effects and would reduce the orbital
overlapping, thus resulting in relatively very low carrier
mobility, even though they have long-range ordered
edge-on orientation.46-48
Unlike TPD1, TPD2 has only an edge-on orientation
before and after the thermal treatment, as shown in
Figures 3c and 3d. To clarify the type of aggregates,
either twisted sandwich-like aggregates or X-aggregates,
present in the TPD2 thin films, it is necessary to analyze
the features of the π-π stacking in the GIWAXS patterns
of the TPD2 samples before and after the thermal
treatment as follows: (i) The (h00) diffraction peaks in
only the qz direction are observed in both the films;
however, no (010) diffraction peaks are observed in the
pristine film. Both the films showed edge-on orientation,
but π-π stacking was not defined in the pristine film. It
became evident as pristine TPD2 films can be classified
into twisted sandwich-like aggregates, though the TPD2
has the absorption properties of H-aggregates. The
twisted sandwich-like aggregates have non-constant π-π
stacking distance because of the twisted angles between
the π-orbitals of the inter-molecular adjacent units. It can
be deduced that the overlap of the π-orbitals between
adjacent units are not constant even if the polymer chains
are aligned. Thus the reduced π-π orbital overlap allows
the excited electrons to fall into the ground state,
resulting in emission as shown in Figure 2 rather than
transport to the next adjacent units. (ii) The intensity of
(h00) was increased and the (010) peak appeared, which
means the film exhibits an enhanced edge-on orientation
and a constant π-π stacking distance. Despite the
improved edge-on orientations, the emission features
appeared in the TPD2 films because the orbital overlap is
significantly reduced by tilting in X-shape between the
molecular stacking level. As the TPD units are involved
in the rigid polymer backbone, the intermolecular
Table 2. Crystallographic information of TPD1 and
TPD2 thin films with pristine and after
thermal treatment at 300 oC.
Out-of-plane
In-plane
Distance
q
(Å-1)
Distance
(Å)
q
(Å-1)
(Å)
(100) 0.24
(010) 1.74
(100) 0.26
26.2
3.6
24.2
12.1
8.3
6.1
3.6
22.4
11.2
22.4
11.2
7.9
Pristine
(100) 0.24
26.2
T
P
D
1
(100) 0.24
(200) 0.48
(300) 0.72
(400) 0.94
(010) 1.76
26.2
13.1
8.7
6.7
3.6
300 oC (200) 0.52
anneali (300) 0.76
ng
(400) 1.03
(010) 1.76
(100) 0.28
(200) 0.56
(100) 0.28
(200) 0.56
(300) 0.8
(400) 1.04
Pristine
ㅡ
ㅡ
ㅡ
T
P
D
2
300 oC
anneali
ng
(010) 1.78
3.5
6
ACS Paragon Plus Environment

Chemistry of Materials
Page 6 of 13
1
2
3
4
5
Surface morphological properties
charge transport properties compared to TPD2. This is
because TPD1 has an H-aggregate formation, which
exhibits a face-to-face π-π orbital overlap, resulting in
high charge-carrier mobility. With the annealing process
at 300 ℃, the intensity of the (h00) diffraction peaks
along the qxy and qz directions increases with enhanced
bimodal packing structure, which is beneficial for 3D
charge transport pathway (Figure 3a).12 Furthermore,
extended surface feature, as shown in the AFM results
(Figure 4a), can provide better percolation pathway.
These combinations can help obtain enhanced charge-
carrier transport properties in optimized TPD1 films.
On the other hand, a relatively low charge carrier
mobility of TPD2 could be attributed to the X-aggregate
formation which reduces the electron orbital overlap.
After the annealing process at 300 °C, the enhanced
charge-carrier mobilities can be explained by the
significant (h00) diffraction peaks along the qz direction,
indicating increased edge-on crystalline domains, as
shown in Figure 3b. The X-aggregate formation induced
by the complicated steric effect would dramatically
decrease the orbital overlapping and therefore result in a
relatively low carrier mobility, even though they have
long-range ordered edge-on orientation. These results
reveal that the type of aggregate is critical for
determining the charge-carrier properties.
6
7
8
9
To clarify the surface morphologies of the TPD1 and
TPD2 films, an atomic force microscope (AFM) was
employed. As shown in Figure 4a, both the TPD1 films,
untreated and treated with thermal annealing process,
exhibit smooth surfaces with root-mean-square
roughness (Rq) values of 0.69 nm and 0.97 nm,
respectively. The Rq values of the TPD1 films after
thermal annealing at 300 °C increases because of the
distinct nanofibrillar structures. In contrast, TPD2 films
(Figure 4b) exhibit relatively rough surface
morphologies because of their low solubility in toluene.
Although the TPD2 film was treated with thermal
annealing, the Rq value increases from 2.38 nm to 2.51
nm.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 4 AFM height images of pristine (left) and
o
after thermal treatment at 300 C (right) of off-
center spin-coated films for TPD1 (a) and TPD2
(b). The size of each scan is 2 μm X 2 μm.
Electrical properties of OFET devices
To investigate the charge carrier transport
characteristics of the TPD-based polymers, top-
gate/bottom-contact (TG/BC) OFET devices were
fabricated using the off-center spin-coating technique.
Figure 5 and Figures S6 and S7 show the transfer and
output characteristics of the OFET devices with TPD-
based polymers, respectively. Table 3 lists the device
parameters. The saturated field-effect mobilities for both
the hole (μsat,h) and electron (μsat,e) were calculated via the
1/2
slope of a linear fit to ISD over the gate voltage Vg in
the saturation regime (at Vd = −80 V for hole and Vd = 80
V for electron, respectively). The OFET devices based on
Figure 5. Transfer characteristics of off-center
spin-coated TPD1 (a,b) or TPD2 (c,d) OFETs at
the saturation region; (a) P-channel properties of
TPD1, (b) N-channel properties of TPD1, (c) P-
channel properties of TPD2 and (d) N-channel
properties of TPD2.
TPD1
show
p-channel
dominant
ambipolar
semiconductor behavior. However, in the case of the
OFET devices with TPD2, an n-channel dominant
ambipolar charge transport is observed. The optimized
hole and electron mobilities were found to be 1.84 cm2
V−1 s−1 and 0.31 cm2 V−1 s−1 for TPD1, and 0.015 cm2 V−1
s−1 and 0.16 cm2 V−1 s−1 for TPD2. Both μsat,h and μsat,e of
the OFET devices employing the TPD-based polymers as
semiconducting layers were enhanced with the increase
in the annealing temperature. TPD1 shows more efficient
ACS Paragon Plus Environment

Page 7 of 13
Chemistry of Materials
1
2
3
4
5
6
7
8
9
orbital overlap from proper molecular aggregation type
Structuralinsight of aggregation and orientationfor
efficient chargetransporting properties
is essential to form the charge carrier pathways, and these
pathways are expected to exhibit a synergetic effect with
molecular orientation for leading to high-efficient charge
carrier transport.
An overall characterization of the polymers was
performed, and it was found that the type of aggregation
of the polymers in the final films, such as H-, J- and X-
aggregation, was indeed important for high charge carrier
mobility of the polymer thin films. In Figure 6, the
schematic illustrations show summarized and visualized
overall results for the aggregation and orientation. As
shown in Figure 6a, when an effective π-π orbital
overlap is originated from the H-aggregates of TPD1, 3D
charge transport pathways are formed with bimodal
orientation of edge-on and face-on, resulting in efficient
charge transport. However, TPD2 exhibits a relatively
low mobility and splitted-emission characteristics,
despite the well-aligned edge-on orientation because of
the tilted TPD unit stacking with an X-shape due to the
steric effects at the molecular level during final film
formation. The efficient charge transporting properties of
H-aggregates are well known, and their structural form
of face-to-face H-stacking is not controversial.30-36 The
conclusion drawn from this study is that the well-formed
On the other hand, it is very difficult to explain the
cause of X-aggregation because of the complicated steric
effects on the polymer chain including the backbone and
side chains. In this study, two TPD-based polymers
were compared, and the stacking features of the
polymer main chains tended to be H-aggregates.
These features of TPD2 are considered to form the X-
aggregates closer to the H-aggregates characteristics,
because they have only slightly tilting angles between
neighboring rigid polymer backbones. Thus, the steric
effect might be explained by both alkyl chain and the
main backbone. Starting from our report, more
systematic studies for which part between main
backbone and alkyl chain is more critical to determine
the aggregate types of semiconducting polymers are
necessary to have more extensive structural insight to
design high performance semiconducting materials.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 6. Schematic illustration for structural insight on aggregation and orientation of TPD1 (a, H-aggregates and
bimodal orientation) and TPD2 (b, X-aggregates and edge-on orientation).
ACS Paragon Plus Environment

Chemistry of Materials
Page 8 of 13
1
2
3
4
5
CONCLUSION
Film morphology characterization
6
7
8
9
In this study, we obtained new structural insight into
the charge transporting properties in TPD-based
polymers that cannot be solely explained in terms of the
type of orientation (edge-on, face-on, or bimodal). Two
types of copolymers comprising mono-TPD or bis-TPD
as the accepting unit were prepared and were found to
have significantly different aggregation states such as H-
and X-aggregates in the final films. As a result, in the
case of TPD1, an effective π-π orbital overlap was found
to originate from the H-aggregates, and 3D charge
transport pathways were formed with a bimodal
orientation, leading to a high efficient charge transport
(1.84 cm2 V−1 s−1 of hole and 0.31 cm2 V−1 s−1 of the
electron). However, in TPD2, the X-aggregate formation
induced by the complicated structural steric effects
would reduce the orbital overlapping and therefore result
in a relatively low carrier mobility, despite having long-
range ordered edge-on orientation (0.015 cm2 V−1 s−1 of
hole and 0.16 cm2 V−1 s−1 of electron). We showed that
the type of aggregation in the final thin film, such as H-
or X-aggregation, is indeed important and perhaps more
important than the orientation to obtain polymers with a
high charge carrier mobility.
The surface morphologies of semiconducting materials
were investigated by using a Digital Instruments
Multimode atomic force microscope (Nanoscope III,
Veeco Instruments, Inc.) at the Korea Basic Science
Institute (KBSI). GIWAXS experiments were performed
using multi axis diffractometer at Beamline 3C of the
Pohang Accelerator Laboratory (PAL). The scattering
images were collected at critical angles identified by the
angle with the highest scattering intensity. The scattering
angles were calibrated to the scattering vector q = (4π/λ)
sin2θ, where λ was the X-ray wavelength and θ was the
scattering angle.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
OFET Device Fabrication and Characterization
OFET devices were fabricated with the top-
gate/bottom-contact (TG/BC) configuration on Corning
XG glass substrates which are patterned with Au/Ni (15
nm/3 nm thick) source/drain electrodes using
conventional lift-off photolithography technique. The
glass substrates were cleaned sequentially by ultra-
sonication in deionized water, acetone, and isopropyl
alcohol. The patterned substrates were exposed by
UV/O3 for 20 min before deposition of the
semiconducting materials. TPD1 and TPD2 solutions
were prepared with a concentration of 10 mg mL−1 in
toluene. These semiconducting materials were off-center
spin-coated at 2000 rpm (3 s acceleration) for 60 s in
nitrogen atmosphere, where the device pattern was
located 20 mm away from the rotation axis of the spin-
coater. Thermal annealing was performed at 150, 200,
250, and 300 °C for 30 min, respectively. Poly(methyl
methacrylate) (PMMA) which was used as dielectric
material was dissolved in n-butyl acetate (80 mg mL-1).
PMMA solution was spun cast onto the semiconductor
layer at 2000 rpm (3 s acceleration) for 60 s, followed by
annealing at 80 °C for 2 h to remove the residual solvents
under nitrogen conditions. The capacitance per unit area
of the dielectric layer (PMMA, 500 nm thick) was 6.0 nF
cm-2. Finally, aluminum gate electrode (50 nm thick) was
thermally evaporated using metal shadow masks. The
electrical properties of the OFET devices were measured
using a Keithley 4200-SCS in a N2-filled glove box.
EXPERIMENTAL SECTION
Material Characterization and measurement
All chemicals materials were purchased from Aldrich
and Alfa and were used without further purification. The
three
monomers,
mono-TPD,
bis-TPD,
and
thienylenevinylene, were prepared based on previous
studies.15, 23, 28, 29 Materials were characterized by means
1
of H NMR spectroscopy (JEOL JNM-LA300WB 400
MHz) processed by ACD/SpecManager. The number
average molecular weight (Mn), the weight average
molecular weight (Mw), and polydispersity (PDI) of the
polymers were determined by gel permeation
chromatography
(GPC)
analysis
in
1,2,4-
trichlorobenzene using polystyrene standards at 130 °C.
Thermal properties of polymers were determined by
means of differential scanning calorimetry (DSC,
TA2010) and thermogravimetric analysis (TGA, TA-
2050) at a heating rate of 10 °C /min under nitrogen
atmosphere. UV-vis absorption data for optical properties
was recorded in dilute toluene solutions and fabricated
by off-centered coating films on a spectrometer Perkin
Elmer, Lamba 750. Photoluminescence characterization
was performed using Raman spectroscopy (LabRAM HR
Evolution, Horiba Jobin-Yvon), off-center spin coated
films of TPD1 and TPD2 were excited at 405 nm and
spectra were recorded between 450 and 1000 nm. Cyclic
ASSOCIATED CONTENT
Supporting Information.
The supporting Information is available free of charge
via the Internet at http://pubs.acs.org.”
Experimental Section (synthetic procedure of polymers)
and characterization (TGA, DSC, Theoretical
Calculations, solution absorption spectra and device
performances)
voltammetry
(CV)
measurements
using
for
electrochemical measurement were performed using an
AUTO with a standard three-electrode electrochemical
cell in 0.1 M solution of tetra-n-butylammonium hexafl
uorophosphate (n-Bu4NPF6) solution in acetonitrile. The
reference electrode was calibrated using a 0.1 M
ferrocene, and working electrodes were prepared by spin-
coating using 10 mg ml−1 polymer solution in toluene.
AUTHOR INFORMATION
Corresponding Author
* kimdy@gist.ac.kr
ACS Paragon Plus Environment

Page 9 of 13
Chemistry of Materials
1
2
3
4
5
6
7
8
9
Present Addresses
5. Back, J. Y.; Yu, H.; Song, I.; Kang, I.;
Ahn, H.; Shin, T. J.; Kwon, S.-K.; Oh, J.
H.; Kim, Y.-H., Investigation of
Structure–Property Relationships in
Diketopyrrolopyrrole-Based Polymer
† School of Materials Science and Engineering, Heeger
Center for Advanced Materials (HCAM), Gwangju
Institute of Science and Technology (GIST)
‡Basic Materials & Chemical R&D, LG chem.
Author Contributions
Semiconductors
via
Side-Chain
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
§These authors contributed equally.
Engineering. Chem. Mater. 2015, 27, (5),
1732-1739.
ACKNOWLEDGMENT
6. Zhao, Z.; Yin, Z.; Chen, H.; Zheng, L.;
Zhu, C.; Zhang, L.; Tan, S.; Wang, H.;
Guo, Y.; Tang, Q.; Liu, Y., High-
Performance, Air-Stable Field-Effect
Transistors Based on Heteroatom-
This work was supported by the National Research
Foundation of Korea(NRF) grant funded by the Korea
government (NRF-2018R1A2A1A05078791). The GIXD
was measured using the synchrotron radiation sources 3C
beamline at the Pohang Accelerator Laboratory (PAL). We
thank the Korea Basic Science Institute (KBSI) for AFM
measurement facilities.
Substituted
Naphthalenediimide-
Copolymers
Benzothiadiazole
Exhibiting Ultrahigh Electron Mobility
up to 8.5 cm V(-1) s(-1). Adv. Mater.
2017, 29, (4), 1602410.
REFERENCES
7. Wang, Z.; Liu, Z.; Ning, L.; Xiao, M.; Yi,
Y.; Cai, Z.; Sadhanala, A.; Zhang, G.;
Chen, W.; Sirringhaus, H.; Zhang, D.,
Charge Mobility Enhancement for
Conjugated DPP-Selenophene Polymer
by Simply Replacing One Bulky
Branching Alkyl Chain with Linear One
at Each DPP Unit. Chem. Mater. 2018,
30, (9), 3090-3100.
1. Oh, J. Y.; Rondeau-Gagne, S.; Chiu, Y.
C.; Chortos, A.; Lissel, F.; Wang, G. N.;
Schroeder, B. C.; Kurosawa, T.; Lopez,
J.; Katsumata, T.; Xu, J.; Zhu, C.; Gu, X.;
Bae, W. G.; Kim, Y.; Jin, L.; Chung, J.
W.; Tok, J. B.; Bao, Z., Intrinsically
stretchable
and
healable
semiconducting polymer for organic
transistors. Nature 2016, 539, (7629),
411-415.
8. Park, S.; Lee, M. H.; Ahn, K. S.; Choi, H.
H.; Shin, J.; Xu, J.; Mei, J.; Cho, K.; Bao,
Z.; Lee, D. R.; Kang, M. S.; Kim, D. H.,
Combinatorial Study of Temperature-
Dependent Nanostructure and Electrical
Conduction of Polymer Semiconductors:
Even Bimodal Orientation Can Enhance
3D Charge Transport. Adv. Funct.
Mater. 2016, 26, (26), 4627-4634.
2. Wang, S.; Xu, J.; Wang, W.; Wang, G. N.;
Rastak, R.; Molina-Lopez, F.; Chung, J.
W.; Niu, S.; Feig, V. R.; Lopez, J.; Lei,
T.; Kwon, S. K.; Kim, Y.; Foudeh, A. M.;
Ehrlich, A.; Gasperini, A.; Yun, Y.;
Murmann, B.; Tok, J. B.; Bao, Z., Skin
electronics from scalable fabrication of
an intrinsically stretchable transistor
array. Nature 2018, 555, (7694), 83-88.
3. Park, S.; Fukuda, K.; Wang, M.; Lee, C.;
Yokota, T.; Jin, H.; Jinno, H.; Kimura, H.;
Zalar, P.; Matsuhisa, N.; Umezu, S.;
Bazan, G. C.; Someya, T., Ultraflexible
Near-Infrared Organic Photodetectors
for Conformal Photoplethysmogram
Sensors. Adv. Mater. 2018, 30, 1802359.
4. Kim, G.; Kang, S. J.; Dutta, G. K.; Han,
Y. K.; Shin, T. J.; Noh, Y. Y.; Yang, C., A
9. Kang, S.-H.; Lee, H. R.; Dutta, G. K.;
Lee, J.; Oh, J. H.; Yang, C., A Role of
Side-Chain
Regiochemistry
of
Thienylene–Vinylene–Thienylene (TVT)
in the Transistor Performance of
Isomeric Polymers. Macromolecules
2017, 50, (3), 884-890.
10. Schroeder, B. C.; Kurosawa, T.; Fu, T.;
Chiu, Y.-C.; Mun, J.; Wang, G.-J. N.; Gu,
X.; Shaw, L.; Kneller, J. W. E.; Kreouzis,
T.; Toney, M. F.; Bao, Z., Taming
Charge Transport in Semiconducting
Polymers with Branched Alkyl Side
Chains. Adv. Funct. Mater. 2017, 27,
(34), 1701973.
thienoisoindigo-naphthalene
polymer
with ultrahigh mobility of 14.4
cm(2)/V.s that substantially exceeds
benchmark values for amorphous silicon
semiconductors. J. Am. Chem. Soc.
2014, 136, (26), 9477-9483.
11. Wang, Y.; Hasegawa, T.; Matsumoto, H.;
ACS Paragon Plus Environment

Chemistry of Materials
Page 10 of 13
1
2
3
4
5
6
7
8
9
Mori, T.; Michinobu, T., High-
Performance n-Channel Organic
7.3%. J. Am. Chem. Soc. 2011, 133, (12),
4250-4253.
Transistors Using High-Molecular-
Weight Electron-Deficient Copolymers
and Amine-Tailed Self-Assembled
Monolayers. Adv. Mater. 2018, 30, (13),
1707164.
18. Guo, X.; Ortiz, R. P.; Zheng, Y.; Kim, M.
G.; Zhang, S.; Hu, Y.; Lu, G.; Facchetti,
A.; Marks, T. J., Thieno[3,4-c]pyrrole-
4,6-dione-based
semiconductors:
polymer
high-
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
toward
12. Kim, N.-K.; Jang, S.-Y.; Pace, G.;
Caironi, M.; Park, W.-T.; Khim, D.; Kim,
J.; Kim, D.-Y.; Noh, Y.-Y., High-
performance, air-stable organic thin-
film transistors. J. Am. Chem. Soc. 2011,
133, (34), 13685-13697.
Performance
Organic
Field-Effect
19. Wu, Q.; Wang, M.; Qiao, X.; Xiong, Y.;
Huang, Y.; Gao, X.; Li, H., Thieno[3,4-
Transistors with Directionally Aligned
Conjugated Polymer Film Deposited
from Pre-Aggregated Solution. Chem.
Mater. 2015, 27, (24), 8345-8353.
c]pyrrole-4,6-dione
Copolymers for High Performance
Field-Effect Transistors.
Containing
13. Zheng, Y. Q.; Yao, Z. F.; Lei, T.; Dou, J.
H.; Yang, C. Y.; Zou, L.; Meng, X.; Ma,
W.; Wang, J. Y.; Pei, J., Unraveling the
Macromolecules 2013, 46, (10), 3887-
3894.
20. Weller, T.; Rundel, K.; Krauss, G.;
McNeill, C. R.; Thelakkat, M., Highly
Solution-State
Structures
Supramolecular
Donor-Acceptor
of
Efficient
Transport in Thieno[3,4-c]pyrrole-
4,6-dione Copolymers: Dramatic
and
Balanced
Charge
Polymers and their Influence on Solid-
State Morphology and Charge-
Transport Properties. Adv. Mater. 2017,
29, (42), 1701072.
Influence of Thieno[3,2-b]thiophene
Comonomer on Alignment and Charge
Transport. J. Phys. Chem. C 2018, 122,
(14), 7565-7574.
14. Khim, D.; Luzio, A.; Bonacchini, G. E.;
Pace, G.; Lee, M. J.; Noh, Y. Y.; Caironi,
M., Uniaxial Alignment of Conjugated
Polymer Films for High-Performance
Organic Field-Effect Transistors. Adv.
Mater. 2018, 30, (20), 1705463.
21. Xu, X.; Li, Z.; Zhang, W.; Meng, X.; Zou,
X.; Di Carlo Rasi, D.; Ma, W.; Yartsev,
A.; Andersson, M. R.; Janssen, R. A. J.;
Wang, E., 8.0% Efficient All-Polymer
Solar Cells with High Photovoltage of
1.1 V and Internal Quantum Efficiency
near Unity. Adv. Energy Mater. 2018, 8,
(1), 1700908.
15. Zou, Y.; Najari, A.; Berrouard, P.;
Beaupre, S.; Aı¨ch, B. R. d.; Tao, Y.;
Leclerc, M., A Thieno[3,4-c]pyrrole-
4,6-dione-Based
Copolymer
for
Efficient Solar Cells. J. AM. CHEM. SOC.
2010, 132, (15), 5330-5331.
22. Pankow, R. M.; Munteanu, J. D.;
Thompson, B. C., Influence of the aryl
spacer in 2,5-dialkoxyphenylene and
16. Chen, G. Y.; Cheng, Y. H.; Chou, Y. J.;
Su, M. S.; Chen, C. M.; Wei, K. H.,
diaryl
substituted
thieno[3,4-
Crystalline
containing fused 2,5-di(thiophen-2-
yl)thieno[2,3-b]thiophene and
conjugated
polymer
c]pyrrole-4,6-dione copolymers. J.
Mater. Chem. C 2018, 6, (22), 5992-
5998.
thieno[3,4-c]pyrrole-4,6-dione units
for bulk heterojunction solar cells.
Chem. Commun. 2011, 47, (17), 5064-
5066.
23. Donaghey, J. E.; Ashraf, R. S.; Kim, Y.;
Huang, Z. G.; Nielsen, C. B.; Zhang, W.;
Schroeder, B.; Grenier, C. R. G.; Brown,
C. T.; D'Angelo, P.; Smith, J.; Watkins,
S.; Song, K.; Anthopoulos, T. D.;
Durrant, J. R.; Williams, C. K.;
17.Chu, T. Y.; Lu, J.; Beaupre, S.; Zhang, Y.;
Pouliot, J. R.; Wakim, S.; Zhou, J.;
Leclerc, M.; Li, Z.; Ding, J.; Tao, Y., Bulk
McCulloch,
I.,
heterojunction
solar
cells
using
and
Pyrroloindacenodithiophene containing
polymers for organic field effect
transistors and organic photovoltaics. J.
Mater. Chem. 2011, 21, (46), 18744-
thieno[3,4-c]pyrrole-4,6-dione
dithieno[3,2-b:2',3'-d]silole copolymer
with a power conversion efficiency of
ACS Paragon Plus Environment

Page 11 of 13
Chemistry of Materials
1
2
3
4
5
6
7
8
9
18752.
Aggregates. J. Am. Chem. Soc. 2018,
140, (17), 5764-5773.
24. Pouliot, J.-R.; Mercier, L. G.; Caron, S.;
Leclerc, M., Accessing New DPP-Based
Copolymers by Direct Heteroarylation
Polymerization. Macromol. Chem. Phys.
2013, 214, (4), 453-457.
32. SPANO, F. C., The Spectral Signatures
of Frenkel Polarons in H- and J-
Aggregates.
ACCOUNTS
OF
CHEMICAL RESEARCH 2009, 43, (3),
429-439.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
25. Qiao, X.; Wu, Q.; Wu, H.; Wang, D.; Li,
H., High performance thin film
transistors based on bi-thieno[3,4-
c]pyrrole-4,6-dione-containing
33. M. KASHA, H. R. R. a. M. A. E.-B., THE
EXCITON MODEL IN MOLECULAR
SPECTROSCOPY. Pure and applied
Chemistry 1965, 11, (3-4), 371-529.
34. Zhou, J.-D.; Zhang, W.-Q.; Liu, L.-L.;
Xie, Z.-Q.; Ma, Y.-G., Aggregation
structures of organic conjugated
molecules on their optoelectronic
properties. Chinese Chemical Letters
2016, 27, (8), 1350-1356.
copolymers: tuning the face-on and
edge-on packing orientations. Polym.
Chem 2016, 7, (4), 807-815.
26. Qiao, X.; Wu, Q.; Wu, H.; Zhang, J.; Li,
H.,
Bithienopyrroledione-Based
Copolymers, Versatile Semiconductors
for Balanced Ambipolar Thin-Film
Transistors and Organic Solar Cells
withVoc> 1 V. Adv. Funct. Mater. 2017,
27, (4), 1604286.
35. Brixner, T.; Hildner, R.; Köhler, J.;
Lambert, C.; Würthner, F., Exciton
Transport in Molecular Aggregates -
From Natural Antennas to Synthetic
Chromophore Systems. Adv. Energy
Mater. 2017, 7, (16), 1700236.
27. Zhang, S.; Qiao, X.; Xiong, Y.; Wu, Q.;
Liu, Z.; Li, H.; Fang, Q., Bi-
thieno[3,4]pyrrole-4,6-dione
copolymers: 1,2-Bis(2-thienyl)ethene
unit vs 1,2-diphenylethene unit.
based
36. Spano, F. C.; Silva, C., H- and J-
aggregate
behavior in
polymeric
Organic Electronics 2018, 56, 146-151.
28. Philippe Berrouard, F. o. G., Jean-Re´mi
Pouliot, Eric Gagnon, Christian Tessier,
and Mario Leclerc, Synthesis and
Characterization of 5-Octylthieno[3,4-
c]pyrrole-4,6-dione Derivatives As
semiconductors. Annu Rev Phys Chem
2014, 65, 477-500.
37. Wang, Y. J.; Li, Z.; Tong, J.; Shen, X. Y.;
Qin, A.; Sun, J. Z.; Tang, B. Z., The
fluorescence
aggregation
properties
behavior
and
of
New
Monomers
for
Conjugated
tetraphenylethene–perylenebisimide
Copolymers. ORGANIC LETTERS 2011,
13, (1), 38-41.
dyads. J. Mater. Chem. C 2015, 3, (15),
3559-3568.
29. Lim, D.-H.; Jang, S.-Y.; Kang, M.; Lee,
S.; Kim, Y.-A.; Heo, Y.-J.; Lee, M.-H.;
Kim, D.-Y., A systematic study on
38. Araya-Hermosilla,
Hermosilla, E.; Torres-Gallegos, C.;
Alarcón-Alarcón, C.; Moreno-
R.;
Araya-
molecular
planarity
and
D–A
Villoslada, I., Sensing Cu2+ by
controlling the aggregation properties
of the fluorescent dye rhodamine 6G
with the aid of polyelectrolytes bearing
different linear aromatic density.
Reactive and Functional Polymers 2013,
73, (11), 1455-1463.
conformation in thiazolothiazole- and
thienylenevinylene-based copolymers
for organic field-effect transistors. J.
Mater. Chem. C 2017, 5, (39), 10126-
10132.
30. Hestand, N. J.; Spano, F. C., Expanded
Theory of H- and J-Molecular
Aggregates: The Effects of Vibronic
Coupling and Intermolecular Charge
Transfer. Chem. Rev. 2018, 118, (15),
7069-7163.
39. Terdale, S.; Tantray, A., Spectroscopic
study of the dimerization of rhodamine
6G in water and different organic
solvents. Journal of Molecular Liquids
2017, 225, 662-671.
31. Cai, K.; Xie, J.; Zhang, D.; Shi, W.; Yan,
Q.; Zhao, D., Concurrent Cooperative J-
Aggregates and Anticooperative H-
40. Zhang, J.; Xu, B.; Chen, J.; Ma, S.; Dong,
Y.; Wang, L.; Li, B.; Ye, L.; Tian, W., An
organic luminescent molecule: what will
ACS Paragon Plus Environment

Chemistry of Materials
Page 12 of 13
1
2
3
4
5
6
7
8
9
happen when the "butterflies" come
45.Rivnay, J.; Mannsfeld, S. C.; Miller, C. E.;
Salleo, A.; Toney, M. F., Quantitative
determination of organic semiconductor
microstructure from the molecular to
device scale. Chem. Rev. 2012, 112,
(10), 5488-5519.
together? Adv. Mater. 2014, 26, (5),
739-745.
41. Xie, Z.; Chen, C.; Xu, S.; Li, J.; Zhang, Y.;
Liu, S.; Xu, J.; Chi, Z., White-light
emission strategy of a single organic
compound with aggregation-induced
emission and delayed fluorescence
properties. Angew. Chem. Int. Ed. 2015,
54, (24), 7181-7184.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
46. Zengqi Xie, B. Y., Feng Li, Gang Cheng,
Linlin Liu, Guangdi Yang, Hai Xu, Ling
Ye, Muddasir Hanif, Shiyong Liu,
Dongge Ma and Yuguang Ma, Cross
Dipole Stacking in the Crystal of
42. Zhou, C.; Tian, Y.; Yuan, Z.; Han, M.;
Wang, J.; Zhu, L.; Tameh, M. S.; Huang,
C.; Ma, B., Precise Design of
Phosphorescent Molecular Butterflies
with Tunable Photoinduced Structural
Change and Dual Emission. Angew.
Chem. Int. Ed. 2015, 54, (33), 9591-
9595.
Distyrylbenzene
Derivative:
The
Approach toward High Solid-State
Luminescence Efficiency. J. AM. CHEM.
SOC. 2005, 127.
47. Kim, H. S.; Long, D.; Noh, Y.-Y.; Hwang,
D.-H., Effect of donor units in
methylated DPP-based polymers on
performance of organic field-effect
transistors. J. Mater. Chem. C 2018, 6,
(39), 10464-10471.
43. Xu, B.; Mu, Y.; Mao, Z.; Xie, Z.; Wu, H.;
Zhang, Y.; Jin, C.; Chi, Z.; Liu, S.; Xu, J.;
Wu, Y. C.; Lu, P. Y.; Lien, A.; Bryce, M.
R.,
Achieving
remarkable
white-light
48. Lee, M. H.; Kim, J.; Kang, M.; Kim, J.;
Kang, B.; Hwang, H.; Cho, K.; Kim, D. Y.,
Precise Side-Chain Engineering of
Thienylenevinylene-Benzotriazole-
Based Conjugated Polymers with
Coplanar Backbone for Organic Field
Effect Transistors and CMOS-like
Inverters. ACS Appl. Mater. Interfaces
2017, 9, (3), 2758-2766.
mechanochromism
and
emission with thermally activated
delayed fluorescence through the
molecular heredity principle. Chem. Sci.
2016, 7, (3), 2201-2206.
44. DeLongchamp, D. M.; Kline, R. J.;
Fischer, D. A.; Richter, L. J.; Toney, M.
F., Molecular characterization of
organic electronic films. Adv. Mater.
2011, 23, (3), 319-337.
ACS Paragon Plus Environment

Page 13 of 13
Chemistry of Materials
1
2
3
4
5
6
TOC
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
ACS Paragon Plus Environment