Intramolecular Locked Dithioalkylbithiophene-Based Semiconductors for High-Performance Organic Field-Effect Transistors

Article abstract of DOI:10.1002/adma.201702414

New 3,3′-dithioalkyl-2,2′-bithiophene (SBT)-based small molecular and polymeric semiconductors are synthesized by end-capping or copolymerization with dithienothiophen-2-yl units. Single-crystal, molecular orbital computations, and optical/electrochemical

Full text of DOI:10.1002/adma.201702414

COMMUNICATION
Semiconductors
www.advmat.de
Intramolecular Locked Dithioalkylbithiophene-Based
Semiconductors for High-Performance Organic
Field-Effect Transistors
Sureshraju Vegiraju, Bo-Chin Chang, Pragya Priyanka, Deng-Yi Huang, Kuan-Yi Wu,
Long-Huan Li, Wei-Chieh Chang, Yi-Yo Lai, Shao-Huan Hong, Bo-Chun Yu,
Chien-Lung Wang, Wen-Jung Chang, Cheng-Liang Liu,* Ming-Chou Chen,*
and Antonio Facchetti*
deposition. However, achieving semi-
New 3,3′-dithioalkyl-2,2′-bithiophene (SBT)-based small molecular and poly-
meric semiconductors are synthesized by end-capping or copolymerization
with dithienothiophen-2-yl units. Single-crystal, molecular orbital computa-
tions, and optical/electrochemical data indicate that the SBT core is com-
conductors with facile synthetic access,
good solubility in organic solvents, and
acceptable device performance remain
challenging and scientifically very inter-
esting. When designing soluble semicon-
ductors, the typical approach consists of
functionalizing π-cores with alkyl/siloalkyl
substituents.[2] However, when doing so,
it is important not to compromise core
planarity at critical inter-ring connectivity
points to avoid π-conjugation disruption, as
well as to enable close intermolecular π–π
stacking, essential for good charge trans-
port. Thus, for nonbenzofused/anellated
systems,[1g,3] an effective design strategy
uses solubilizing substituents resulting
⋯
pletely planar, likely via S(alkyl) S(thiophene) intramolecular locks. Therefore,
compared to semiconductors based on the conventional 3,3′-dialkyl-2,2′-
bithiophene, the resulting SBT systems are planar (torsional angle <1°)
and highly π-conjugated. Charge transport is investigated for solution-
sheared films in field-effect transistors demonstrating that SBT can enable
good semiconducting materials with hole mobilities ranging from ≈0.03 to
1.7 cm2 V−1 s−1. Transport difference within this family is rationalized by film
morphology, as accessed by grazing incidence X-ray diffraction experiments.
Significant efforts have involved the development of organic
materials for various optoelectronic applications.[1] Particu-
larly, several studies have addressed solution-processable small
molecular and polymeric semiconductors for organic field-effect
transistors (OFETs), enabling device fabrication via inexpensive
and potentially high-throughput processes compared to vacuum
in a solid-state “conformational lock.” To this end, the most

promising substituent is an alkoxy group ( OR) couple with a
sulfur-containing heterocycle (S-Het) such as thiophene and thi-
azole (Figure 1).[4] Compared to conventional alkyl-substituted
systems, these alkoxylated π-conjugates possess weak intramo-
⋯
lecular S O contacts which not only eliminate chain repulsive
interactions with neighboring arene units but also enhance
molecular planarity and solid state crystallinity, thus enabling
high OFETs mobility (µmax = 0.01–0.5 cm2 V−1 s−1). In contrast to
Dr. S. Vegiraju, Dr. P. Priyanka, L.-H. Li, Y.-Y. Lai, B.-C. Yu,
Dr. W.-J. Chang, Prof. M.-C. Chen
Department of Chemistry
National Central University
Taoyuan 32001, Taiwan
⋯
the previous approach, intramolecular lock via S X interactions
(X = S, N, halogen) are far more rare[5] and only two pioneering
studies report the use of X = thioalkyl substitution.[6] This result
may be due to the limited synthetic access of these structures
and reported poor charge transport characteristics in OFETs
(µmax = 0.0004 cm2 V−1 s−1).[6b] In this paper, we report the syn-
thesis of new semiconductors based on the 3,3′-dithioalkyl-2,2′-
bithiophene core (SBT; Figure 2). Our data indicate that locking/
planarizing occurring in the SBT structure enhance molecular
packing, and that the use of a proper alkyl group (nC14H29)
combined with an optimal film solution deposition method can
enable significant OFETs mobilities.
E-mail: mcchen@ncu.edu.tw
B.-C. Chang, D.-Y. Huang, W.-C. Chang, S.-H. Hong, Prof. C.-L. Liu
Department of Chemical and Materials Engineering
National Central University
Taoyuan 32001, Taiwan
E-mail: clliu@ncu.edu.tw
K.-Y. Wu, Prof. C.-L. Wang
Department of Applied Chemistry
National Chiao Tung University
Hsinchu 30010, Taiwan
Prof. A. Facchetti
Department of Chemistry and the Materials Research Center
Northwestern University
Evanston, IL 60208, USA
The SBT core was previously prepared from lithiation of
3-bromothiophene (10) and treatment with elemental sulfur,
followed by alkylation and then homocoupling with 2-lith-
ium-3-thioalkylthiophene (Figure 2a).[6a] Unfortunately, this
synthetic route (10-9-6) suffers from low yields and difficult
E-mail: a-facchetti@northwestern.edu
DOI: 10.1002/adma.201702414
©
1702414 (1 of 8)
2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Mater. 2017, 1702414

www.advancedsciencenews.com
www.advmat.de
The optical, thermal, and electrochem-
ical properties of 1–5 are summarized in
Table 1. Thermogravimetric analysis (TGA,
Figure S1, Supporting Information) revealed
that SBT 1–3 exhibit good thermal stability,
with ≈5 wt% loss occurring at >330 °C.
Differential scanning calorimetry (DSC,
Figure S2, Supporting Information) showed
Figure 1. Example of building blocks used to construct polymeric semiconductors and having
⋯
that the 1–3 melt at >140 °C versus only
90 °C for BT-based (4), indicating stronger
S
O intramolecular locks.
accessibility due to the formation of other non-regioselective
byproducts, such as head–tail or tail–tail derivatives. Barbarella
and co-workers first synthesized 6 via ultrasound and micro-
wave irradiation in four steps, and demonstrated OFET-active
semiconductors, yet with negligible performance.[6b] In the cur-
rent work, we achieved SBT cores in a regiospecific strategy in
two steps (10-8-6, Figure 2a), with a satisfactory overall yield
>70%. Thus, 3-bromothiophene (10) was selectively deproto-
nated with LDA, which then underwent homocoupling in the
presence of ZnCl2/CuCl2 to produce 8.[7] Nucleophilic substi-
tution of the latter with alkylthiol lithium in the presence of
CuO/KI produces 6 after facile purification. The SBT core was
then end-capped with dithienothiophene (DTT),[8] via Stille
cross-coupling reaction of 7a–c with tributylstannyl-DDT (11)
to afford the small molecules 1–3, respectively (Figure 2b).
For comparison, the bithiophene (BT)-based molecule 4 was
synthesized by reacting 7d with 11. Finally, the SBT-based
copolymer (5) was obtained via polymerization of 7a with
the di-stannylated DTT (12) (Figure 2c, see the Supporting
Information for details).
intermolecular interactions for the SBT molecules. The solu-
tion optical absorption spectra of 1–3 are almost identical
(λmax ≈ 438 nm, Figure 3a) and independent of the thioalkyl
chains. The abovementioned absorption values are signifi-
cantly red shifted compared to the BT analog 4 (λmax ≈ 396 nm),
suggesting enhanced π-conjugation within the SBT core via
intramolecular lock (vide infra). To examine the extent of the
⋯
intramolecular S S lock and whether it plays a role in planar-
izing the BT unit, considering the contrasting literature data,[9]
temperature-dependent UV–vis measurements in solution
were carried out for molecules 1 and 4. As shown in Figure S3a
(Supporting Information), as the temperature increases from
25 to 85 °C (ΔT = 60 °C), the optical absorption and λmax of
4 are nearly unchanged (Δλmax = 2 nm). In contrast, the λmax
of compound 1 is significantly blue shifted (Δλmax = 24 nm).
This result clearly indicates that the SBT unit in 1 is less con-
jugated at higher temperatures, thus suggesting that the intra-
⋯
molecular S S interactions are also operative in the isolated 1
molecules and that planarization of 1, as demonstrated by the
crystal structure, cannot only be the driven by packing forces.
Figure 2. a) Synthetic routes to the SBT core. b) Preparation and structures of small molecules 1–4 and c) Polymer 5.
©
Adv. Mater. 2017, 1702414
1702414 (2 of 8)
2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

www.advancedsciencenews.com
www.advmat.de
Table 1. Optical, electrochemical, and thermal properties of 1–5 and their OFETs performance.
a)
b)
Compound
Tm
[°C]
Td
[°C]
Potential
[V]
HOMO
[eV]
LUMO
[eV]
I
ON/IOFF
[–]
Vth
[V]
λmax
µ
max (µavg
)
[nm]
[cm2 V−1 s−1
]
Eox
Ered
DPVc)
DFT
DPVc)
−2.58
−2.58
−2.54
−2.26
−3.29g)
DFT
−1.62
−1.62
−1.66
−1.94
n.d.f)
−5.07
−5.07
−5.08
−5.22
−5.15
−4.93d)
−4.93d)
−4.93d)
−5.06e)
n.d.f)
−2.24d)
−2.24d)
−2.24d)
−1.86e)
n.d.f)
1.7 (1.0 0.3)
0.07 (0.05 0.02)
0.03 (0.02 0.01)
≈10−7 (–)
≈104–106
≈104–106
≈103–104
<10
−20
5
2
1
2
3
4
5
140
169
176
90
352
337
330
375
344
438
438
432
396
504
0.87
0.87
0.88
1.02
0.95
−10
−5
2
n.d.f)
−15
>395
0.1 (0.04 0.02)
≈105–106
3
a)In o-C6H4Cl2; b)Average of at least ten devices; c)By DPV in o-C6H4Cl2 at 25 °C, Eox = oxidative potential, Ered = reductive potential, HOMO = −(4.2+Eox); LUMO = −(4.2+Ered);
d)By DFT calculation based on thio-ethyl side group; e)By DFT calculation based on propyl side group; f)Not determined; g)Estimated from HOMO + optical bandgap.
The HOMO/LUMO levels (Figure 3b) are −5.07/−2.58 eV for
1–3, and −5.22/−2.26 eV for BT 4, respectively, as estimated
from the differential pulse voltammetry (DPV, Figure S3b,
Supporting Information). This result indicates that the pre-
sent SBT systems have far smaller energy gaps (≈2.5 V) than
the BT analog 4 (≈3.0 V) and that they are more electron-rich.
Finally, polymer 5 exhibited the smallest energy gap of 1.86 V
with HOMO/LUMO of −5.15/−3.29 eV, derived from DPV. The
density functional theory (DFT)-derived HOMO/LUMO energy
gaps for the 1–3 (≈2.7 V; Figure S4, Supporting Information)
are also smaller than that for 4 (≈3.2 V), which agrees well with
the optical and electrochemical data.
Single crystals of the two SBT-based small molecules 2 and
3 were obtained by a slow solvent evaporation method from
hexanes and dichloromethane solvent mixture, and are shown
in Figures 4 and 5. Compound 2 crystallizes in a monoclinic
space group P21/c (as summarized in Table S1, Supporting
two end-capped DTT fused-thiophene moieties are also almost
coplanar to the SBT core, with small dihedral angles of <1° in
both 2 and 3, disclosing a potentially excellent intramolecular
π–π interaction among both capped DTT and the central SBT
core. The average interplanar distance between the SBT mol-
ecules in both compounds is ≈3.61 Å (Figure 4c/5c), and the
⋯
shortest intermolecular S S distance is 3.67 Å for 2 and 3.80 Å
for 3 (Figures S5 and S6, Supporting Information). The latter
molecule (2) exhibits a herringbone angle of 115.2° (as shown
in Figure 4g) and a slipping angle of 53.2° in the direction of
the long molecular axis (Figure 4b). Similarly, cofacial packing
of SBT 3 (Figure 5g) shows a tilting angle of 52.5° (Figure 5b).
The intramolecular planar structures and intermolecular short
packing distances of both SBT crystal structures suggest
favorable conditions for intra- and intermolecular π–π orbital
interaction to achieve very good charge transport in solid films
(µmax = 1.7 cm2 V−1 s−1 for SBT (1) in thin film transistor meas-
urements, as shown in Table 1).
Information) and exhibits
a herringbone packing motif
(Figure 4e,f). In contrast, compound 3 crystallizes in a triclinic
space group P-1 and exhibits a cofacial stacking arrangement
(Figure 5e,f). Single-crystal analyses clearly reveal the alkyl
chains play strong influence in the crystal lattice. Nonethe-
less, regardless of the thioalkyl chains or the packing motif of
SBTs, the four S atoms at inter-ring locations are fully planar
DFT computations corroborate the planarity of the SBT
core, with skeletal distortion of <5° (Figure S7a, Supporting
Information). In sharp contrast, the optimized geometry of
the alkyl chain substituted molecule 4 reveals a significantly
distorted BT core (≈60°, Figure S7b, Supporting Information).
For example, the crystal structure of the alkyl-substituted BT
intermediate 7 is known and it features an inter-ring torsional
angle of 67.3°.[10] All these experimental and computational
data are in agreement with the greater steric demand of alkyl
versus thioalkyl substituents and consistent with the optical
⋯
and feature S(Thio) S(R) intramolecular distances of ≈3.09 Å
(Figures 4a and 5a), which are largely below the sum of the van
der Waals radii of two S atoms (≈1.8 Å), indicating a strong
⋯
S(Thio) S(R) intramolecular interaction. Furthermore, the
(b)
(a)
1.0
-2.26
-2
-3
-4
-5
-6
6a
-2.54
-2.58 -2.58
1
2
3
4
5
0.8
0.6
0.4
0.2
0.0
-3.29
4
2
1
3
5
-5.07
-5.07
-5.08
-5.15
-5.22
300 400 500 600 700 800
Wavelength (nm)
Figure 3. a) Optical absorption and b) HOMO/LUMO levels of 1–5.
©
1702414 (3 of 8)
2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Mater. 2017, 1702414

www.advancedsciencenews.com
www.advmat.de
Figure 4. a–d,f) Single-crystal structure of 2 in stick and e,g) space filling models. The sulfur atoms are specified in red color. a) Top view of two stacking
⋯
SBT molecules, top SBT molecule is in darker color and bottom one is in lighter color. The molecular length of SBT (2) is 23.7 Å and the S(Thio) S(R)
intramolecular distance is ≈3.09 Å. b) Front view of two stacking SBT molecules. The two end-capped DTTs are almost coplanar to the central SBT
core, with small dihedral angles of <1°. The slipping angle of SBT stacks is 53.2°. c) Side view of two stacking SBT molecules. The interplanar distance
between the SBT layers is ≈3.60 Å. d) Top view of the SBT molecular packing, revealing SBT possessed excellent intermolecular stacking. e) Front view
of SBT molecular in space filling model, the alkyl chains are omitted for clarity. f) Side view of the SBT molecular packing, SBT exhibits herringbone
packing. The two alkyl chains on each SBT molecule are located on the opposite core face. g) Side view of SBT molecular in space filling model with
herringbone angle of 115.2°. The alkyl chains are omitted for clarity.
Figure 5. a–d,f) Single-crystal structure of 3 in stick and e,g) space filling models. The sulfur atoms are specified in red color. a) Top view of two stacking
⋯
SBT molecules, top SBT molecule is in darker color and bottom one is in lighter color. The molecular length of SBT (3) is 23.7 Å and the S(Thio) S(R)
intramolecular distance is ≈3.087 Å. b) Front view of two stacking SBT molecules. The two end-capped DTTs are almost coplanar to the central SBT
core, with small dihedral angles of <1°. The slipping angle of SBT stacks is 52.5°. c) Side view of two stacking SBT molecules. The interplanar distance
between the SBT layers is ≈3.61 Å. d) Top view of the SBT molecular packing, revealing SBT possessed excellent intermolecular stacking. e) Front
view of SBT molecular in space filling model, the alkyl chains are omitted for clarity. f) Side view of the SBT molecular packing, SBT exhibits cofacial
packing. The two alkyl chains on each SBT molecule are located on the opposite core face. g) Side view of SBT molecule in space filling model. The
alkyl chains are omitted for clarity.
©
Adv. Mater. 2017, 1702414
1702414 (4 of 8)
2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

www.advancedsciencenews.com
www.advmat.de
characteristics of 1, in which the sharing
direction is perpendicular to the source/
drain contact lines. The highest hole mobility
(µmax) of 1.7 cm2 V−1 s−1 and an ON/OFF cur-
rent ratio (ION/IOFF) of ≈106 was achieved for
1. The average mobility (µavg) across all the
devices is also high, with values of 1.0 0.3
cm2 V−1 s−1, with an average threshold voltage
(Vth) and ION/IOFF of −20 5 V and 104–106,
respectively. The OFETs based on 2 and 3
exhibited similar, but lower, µmax of 0.07 and
0.03 cm2 V−1 s−1, respectively (Figure S10a–d,
Supporting Information), whereas a negli-
gible µmax of ≈10−7 cm2 V−1 s−1 was measured
for 4 (Figure S10e, Supporting Information).
The enhanced charge transport of 1–3 versus
4 is in agreement with the SBT molecule
electronic and structural data, favoring intra-
molecular conjugation, molecular planariza-
⋯
tion probably via intramolecular S S con-
tacts, and strong intermolecular interactions.
An interesting question is how to ration-
alize the OFETs performance difference
between
1 and 2 small molecules. To
this end, we analyzed and compared the
grazing incidence X-ray diffraction (GIXRD,
Figure S11, Supporting Information) pat-
terns of solution-sheared films of 1 and 2.
Figure S12 (Supporting Information) shows
the GIXRD patterns of 2 and the corre-
sponding packing structure with respect to
Figure 6. a) Schematic diagram of solution-shearing method. b) Photographic and cross-polar-
ized optical microscopic image of solution-sheared 1 crystal. c) Output (Vg = 0 to −80 V, −20 V
interval), and d) transfer (Vd = −80 V) characteristics of OFETs based on solution-sheared 1
crystal.
and electrochemical data. For molecule 1, computed HOMO/
LUMO energy levels, and thus Eg, by the B3LYP functional are
closer to the experimental values derived from DPV than those
calculated using CAM-B3LYP and WB97XD.
the shearing direction. The lattice parameters determined from
Figure S12a (Supporting Information) are b = 13.5 Å, c = 25.6
Å and α = 90°, and from Figure S12b (Supporting Information)
are a = 4.9 Å, c = 25.6 Å, and β = 90°. These lattice parameters
closely match those determined from the single-crystal struc-
ture of 2 (Table S2, Supporting Information), suggesting that
the shearing process negligibly affects the lattice structure of
this molecule. Figure S12c (Supporting Information) shows the
packing structure on the bc projection. Since the c-axis is along
the out-of-plane direction (qz), 2 packs into a herringbone-like
arrangement with alternating layers of thiohexyl side chains/
conjugated backbones along the Si-substrate normal direction.
The center-to-center distance between the backbone layers is
c/2 = 13.3 Å. In Figure S12d (Supporting Information), ordered
π–π stacking of 2 can be clearly seen within the backbone layer
along the a-axis, which is parallel to the long axis of the crystal,
thus corroborating the good charge transport along the crystal-
line film.
Figure 7a,b shows the GIXRD patterns of a solution-sheared
crystal of 1. The lattice parameters determined from Figure 7a
are b = 13.4 Å, c = 18.4 Å, and α = 110°, and from Figure 7b
are a = 4.9 Å, c = 18.4 Å, and β = 102°. Due to the difficulty in
growing single crystals of 1, electron diffraction (ED, Figure 7c)
was performed with the electron beam incident from the top of
the crystal (illustrated in Figure S10, Supporting Information)
to show the a*b* reciprocal lattice of the crystal. The lattice
parameter determined from Figure 7c is γ = 100°. By com-
bining the GIXRD and ED results the lattice parameters of the
Next, we investigated thin-film fabrication using 1–5 via
solution deposition. Figure 6a shows the schematic depiction of
the solution-shearing technique, as first demonstrated by Bao
and co-workers.[11] For films fabricated by solution shearing
from chlorobenzene solution (1–2 mg mL−1), with a speed of
15–20 µm s−1 and a substrate temperature of 50 °C, large 1
crystal domains covering an area of ≈1 × 1 cm2 can be fabri-
cated (Figure 6b). Polarized optical microscopy (POM) imaging
reveals a clear optical birefringence of a broad well-aligned crys-
talline array along the shearing direction (Figure 6b). These
crystals have an elongated microribbon-like structure with uni-
form widths of tens of micrometers and lengths of millimeters,
and with thicknesses ranging from 50 to 60 nm, as measured
by profilometry. Similarly oriented, yet smaller, microdomains
can be observed for 2 (Figure S8a,b, Supporting Information)
and 3 (Figure S8c,d, Supporting Information) films, whereas
those of 4 have no preferential orientation versus the shearing
direction (Figure S8e, Supporting Information).
To evaluate the SBT-based derivatives as organic semicon-
ductors, bottom-gate top-contact OFETs (Figure S9, Supporting
Information) were fabricated using solution-sheared crystals
deposited on (2-phenylethyl) trichlorosilane (PETS)-treated Si/
SiO2 substrates (for details see the Supporting Information).
Figure 6c,d shows representative OFETs output and transfer
©
1702414 (5 of 8)
2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Mater. 2017, 1702414

www.advancedsciencenews.com
www.advmat.de
Figure 7. GIXRD pattern of 1 for the incident X-ray a) parallel and b) perpendicular with respect to the shearing direction. c) Selected area electron
diffraction (SAED) pattern. d) AFM image and surface profile of solution-sheared 1 crystal. Packing structures of 1 in the crystallographic e) bc and
f) ac cells.
solution-sheared crystal of 1 were fully characterized and are
summarized in Table S2 (Supporting Information). Comparing
the lattices of 1 and 2, it can be found that the increase in the
side-chain length does not significantly change the ab dimen-
sions, but expands the center-to-center distance between the
backbone layers from 13.3 Å (c/2 in 2) to 18.4 Å in 1, and
distorts the lattice from monoclinic to triclinic. A layered
morphology with a step height of ≈19 Å was also observed
in the atomic force microscopy (AFM) image of the 1 crystal
(Figure 7d), supporting the view that the longer thiotetradecyl
side chains in 1 increase the distance between the backbone
layers, as illustrated in Figure S12 (Supporting Information).
Because the lateral dimension of 1 with its two thiotetradecyl
groups fully extended is 43.1 Å (Figure S13, Supporting Infor-
mation), to occupy the side chains within a c-axis of 18.4 Å,
it is reasonable to consider that the side chains are interdigi-
tated and tilted. The proposed packing model for 1 is shown
in Figure 7e. DeLongchamp et al. showed that the interdigi-
tated side chains help to interlock the adjacent layers.[12] The
interlayer registry enhanced the lateral order and increased
the crystalline domain sizes of conjugated polymers, which
consequently improved semiconductor charge transport. In
©
Adv. Mater. 2017, 1702414
1702414 (6 of 8)
2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

www.advancedsciencenews.com
www.advmat.de
Figure 7a,b, the clear diffraction spots in the quadrant indi-
cate that 1 also packs with good interlayer registry along the
c-axis. In Figure 7c, the shape of ED spots along the a direction
and the uniform morphology also indicate the long correlation
length of 1 along the crystal long axis. Moreover, unlike the
c-centered monoclinic lattice of 2, which contains herringbone-
arranged conjugated backbone layers, the triclinic lattice of 1 is
a primitive lattice, suggesting that the backbone layers can only
be arranged parallel (not herringbone-like). The 1 core within
the backbone layer may thus stagger with adjacent molecules
in a slipped face-to-face manner, providing an optimal charge
transport pathway with a higher dimensionality, in agreement
with the substantial charge transport data.
Finally, to expand the generality of the structural strate-
gies based on the SBT unit, in preliminary experiments we
also synthesized the alternating copolymer 5 (Figure 2c).
In contrast to known BT-based polymers,[13] 5 exhibits a
far lower bandgap of ≈1.78 eV and a HOMO level close to
−5 eV. OFETs fabricated with solution-sheared 5 films exhibit
a µmax ≈ 0.1 cm2 V−1 s−1 with an ION/IOFF of ≈106 (Figure S14,
Supporting Information). The GIXRD pattern of 5 films shows
a high degree of molecular order in the out-of-plane direction,
as evidenced by the strong lamellar (100) and (200) diffrac-
tion peak (Figure S15, Supporting Information), resulting in
a d-spacing of 20.5 Å.
Keywords
dithienothiophene,
transistors, solution-shearing
dithioalkylbithiophene,
organic
field-effect
Received: May 1, 2017
Revised: June 11, 2017
Published online:
[1] a) A. Salleo, Nat. Mater. 2015, 14, 1077; b) J. F. M. Hardigree,
H. E. Katz, Acc. Chem. Res. 2014, 47, 1369; c) J. Roncali, P. Leriche,
P. Blanchard, Adv. Mater. 2014, 26, 3821; d) X. Yang, D. Liu,
Q. Miao, Angew. Chem. Int. Ed. 2014, 53, 6786; e) B. He, A. B. Pun,
D. Zherebetskyy, Y. Liu, F. Liu, L. M. Klivansky, A. M. McGough,
B. A. Zhang, K. Lo, T. P. Russell, L. Wang, Y. Liu, J. Am. Chem. Soc.
2014, 136, 15093; f) T. T. Steckler, P. Henriksson, S. Mollinger,
A. Lundin, A. Salleo, M. R. Andersson, J. Am. Chem. Soc. 2014,
136, 1190; g) Y. Yuan, G. Giri, A. L. Ayzner, A. P. Zoombelt,
S. C. B. Mannsfeld, J. Chen, D. Nordlund, M. F. Toney, J. Huang,
Z. Bao, Nat. Commun. 2014, 5, 3005; h) D. M. DeLongchamp,
R. J. Kline, D. A. Fischer, L. J. Richter, M. F. Toney, Adv. Mater.
2011, 23, 319; i) P. F. Green, R. A. Vaia, H. E. Katz, T. Russell,
A. Salleo, G. Malliaras, MRS Commun. 2015, 5, 95; j) L. Zhang,
T. Yang, L. Shen, Y. Fang, L. Dang, N. Zhou, X. Guo, Z. Hong,
Y. Yang, H. Wu, J. Huang, Y. Liang, Adv. Mater. 2015, 27, 6496;
k) B. Kan, Q. Zhang, M. Li, X. Wan, W. Ni, G. Long, Y. Wang,
X. Yang, H. Feng, Y. Chen, J. Am. Chem. Soc. 2014, 136, 15529;
l) S. Himmelberger, K. Vandewal, Z. Fei, M. Heeney, A. Salleo,
Macromolecules 2014, 47, 7151; m) X. Guo, A. Facchetti, T. J. Marks,
Chem. Rev. 2014, 114, 8943; n) F. Gohier, P. Frère, J. Roncali, J. Org.
Chem. 2013, 78, 1497; o) T. Erdmann, S. Fabiano, B. Milián-Medina,
D. Hanifi, Z. Chen, M. Berggren, J. Gierschner, A. Salleo, A. Kiriy,
B. Voit, A. Facchetti, Adv. Mater. 2016, 28, 9169; p) C. B. Nielsen,
A. Giovannitti, D.-T. Sbircea, E. Bandiello, M. R. Niazi, D. A. Hanifi,
M. Sessolo, A. Amassian, G. G. Malliaras, J. Rivnay, I. McCulloch,
J. Am. Chem. Soc. 2016, 138, 10252; q) D. Ji, X. Xu, L. Jiang,
S. Amirjalayer, L. Jiang, Y. Zhen, Y. Zou, Y. Yao, H. Dong, J. Yu,
H. Fuchs, W. Hu, J. Am. Chem. Soc. 2017, 139, 2734; r) D. Zhao,
S. Fabiano, M. Berggren, X. Crispin, Nat. Commun. 2017, 8, 14214;
s) H. Abdalla, S. Fabiano, M. Kemerink, Phys. Rev. B 2017, 95,
085301; t) S. Z. Bisri, V. Derenskyi, W. Gomulya, J. M. Salazar-Rios,
M. Fritsch, N. Fröhlich, S. Jung, S. Allard, U. Scherf, M. A. Loi,
Adv. Electron. Mater. 2016, 2, 1500222; u) B. Nketia-Yawson,
S.-J. Kang, G. D. Tabi, A. Perinot, M. Caironi, A. Facchetti, Y.-Y. Noh,
Adv. Mater. 2017, 29, 1605685.
In conclusion, new SBT-based small molecules (1–3) and a
polymer (5) were synthesized with the aim of understanding the
⋯
extent of the S S intramolecular lock in SBT and whether the
use of this unit is a good strategy to semiconductor materials.
A systematic study of the electronic structure, molecular and
thin-film packing, and charge transport properties of solution-
sheared films was performed. Our preliminary results indicate
that OFETs based on solution-sheared small molecular (1) and
polymeric (5) films exhibit µmax of ≈1.7 and ≈0.1 cm2 V−1 s−1,
respectively, due to the considerable π-conjugation, planar struc-
ture, close π-stacked packing, and highly textured films. Perfor-
mance optimization of SBT-based semiconductors for different
optoelectronic devices will include the screening of different-SR
solubilizing functionalities and (hetero) aromatic co-units.
Supporting Information
[2] a) M. M. Payne, S. R. Parkin, J. E. Anthony, C.-C. Kuo, T. N. Jackson,
J. Am. Chem. Soc. 2005, 127, 4986; b) F. S. Melkonyan, W. Zhao,
M. Drees, N. D. Eastham, M. J. Leonardi, M. R. Butler, Z. Chen,
X. Yu, R. P. H. Chang, M. A. Ratner, A. F. Facchetti, T. J. Marks,
J. Am. Chem. Soc. 2016, 138, 6944; c) C. K. Frederickson, B. D. Rose,
M. M. Haley, Acc. Chem. Res. 2017, 50, 977; d) C. Zhang, Y. Zang,
F. Zhang, Y. Diao, C. R. McNeill, C.-a. Di, X. Zhu, D. Zhu,
Adv. Mater. 2016, 28, 8456; e) S. Vegiraju, G.-Y. He, C. Kim,
P. Priyanka, Y.-J. Chiu, C.-W. Liu, C.-Y. Huang, J.-S. Ni, Y.-W. Wu,
Z. Chen, G.-H. Lee, S.-H. Tung, C.-L. Liu, M.-C. Chen, A. Facchetti,
Adv. Funct. Mater. 2017, 27, 1606761; f) N. Zhou, S. Vegiraju, X. Yu,
E. F. Manley, M. R. Butler, M. J. Leonardi, P. Guo, W. Zhao, Y. Hu,
K. Prabakaran, R. P. H. Chang, M. A. Ratner, L. X. Chen, A. Facchetti,
M.-C. Chen, T. J. Marks, J. Mater. Chem. C. 2015, 3, 8932; g) J. Youn,
S. Vegiraju, J. D. Emery, B. J. Leever, S. Kewalramani, S. J. Lou,
S. Zhang, K. Prabakaran, Y. Ezhumalai, C. Kim, P.-Y. Huang,
C. Stern, W.-C. Chang, M. J. Bedzyk, L. X. Chen, M.-C. Chen,
A. Facchetti, T. J. Marks, Adv. Electron. Mater. 2015, 1, 1500098.
Supporting Information is available from the Wiley Online Library or
from the author.
Acknowledgements
S.V and B.-C.C. contributed equally to this work. The authors
acknowledge the financial support received from the Ministry of Science
and Technology of Taiwan (MOST). The authors thank Beamline
TLS 13A1/17A1 (National Synchrotron Radiation Research Center
(NSRRC) of Taiwan) for providing beamtime. The discussion with
Dr. Chun-Jen Su of NSRRC is also highly appreciated.
Conflict of Interest
The authors declare no conflict of interest.
©
1702414 (7 of 8)
2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Mater. 2017, 1702414

www.advancedsciencenews.com
www.advmat.de
[3] a) J. Youn, S. Kewalramani, J. D. Emery, Y. Shi, S. Zhang,
H.-C. Chang, Y.-J. Liang, C.-M. Yeh, C.-Y. Feng, H. Huang, C. Stern,
L.-H. Chen, J.-C. Ho, M.-C. Chen, M. J. Bedzyk, A. Facchetti,
T. J. Marks, Adv. Funct. Mater. 2013, 23, 3850; b) P.-Y. Huang,
L.-H. Chen, Y.-Y. Chen, W.-J. Chang, J.-J. Wang, K.-H. Lii, J.-Y. Yan,
J.-C. Ho, C.-C. Lee, C. Kim, M.-C. Chen, Chem. Eur. J. 2013, 19, 3721.
[4] a) X. Guo, F. S. Kim, S. A. Jenekhe, M. D. Watson, J. Am. Chem. Soc.
2009, 131, 7206; b) X. Guo, J. Quinn, Z. Chen, H. Usta, Y. Zheng,
Y. Xia, J. W. Hennek, R. P. Ortiz, T. J. Marks, A. Facchetti, J. Am.
Chem. Soc. 2013, 135, 1986; c) H. Huang, Z. Chen, R. P. Ortiz,
C. Newman, H. Usta, S. Lou, J. Youn, Y.-Y. Noh, K.-J. Baeg,
L. X. Chen, A. Facchetti, T. Marks, J. Am. Chem. Soc. 2012, 134,
10966; d) H. G. Kim, B. Kang, H. Ko, J. Lee, J. Shin, K. Cho,
Chem. Mater. 2015, 27, 829; e) X. Guo, Q. Liao, E. F. Manley,
Z. Wu, Y. Wang, W. Wang, T. Yang, Y.-E. Shin, X. Cheng, Y. Liang,
L. X. Chen, K.-J. Baeg, T. J. Marks, X. Guo, Chem. Mater. 2016, 28,
2449; f) J.-H. Dou, Y.-Q. Zheng, Z.-F. Yao, Z.-A. Yu, T. Lei, X. Shen,
X.-Y. Luo, J. Sun, S.-D. Zhang, Y.-F. Ding, G. Han, Y. Yi, J.-Y. Wang,
J. Pei, J. Am. Chem. Soc. 2015, 137, 15947; g) W. Zhang, K. Shi,
J. Huang, D. Gao, Z. Mao, D. Li, G. Yu, Macromolecules 2016, 49,
2582; h) W. Zhang, Z. Mao, N. Zheng, J. Zou, L. Wang, C. Wei,
J. Huang, D. Gao, G. Yu, J. Mater. Chem. C 2016, 4, 9266; i) S. Shi,
Q. Liao, Y. Tang, H. Guo, X. Zhou, Y. Wang, T. Yang, Y. Liang,
X. Cheng, F. Liu, X. Guo, Adv. Mater. 2016, 28, 9969; j) W. Zhang,
Z. Mao, J. Huang, D. Gao, G. Yu, Macromolecules 2016, 49, 6401;
k) H. Huang, N. Zhou, R. P. Ortiz, Z. Chen, S. Loser, S. Zhang,
X. Guo, J. Casado, J. T. López Navarrete, X. Yu, A. Facchetti,
T. J. Marks, Adv. Funct. Mater. 2014, 24, 2782; l) Y. Liu, Z. Zhang,
S. Feng, M. Li, L. Wu, R. Hou, X. Xu, X. Chen, Z. Bo, J. Am. Chem.
Soc. 2017, 139, 3356.
Y. Deng, H. Tian, J. Zhang, D. Yan, Y. Geng, F. Wang, Adv. Mater.
2017, 29, 1606217.
[6] a) F. Raymond, N. D. Césare, M. Belletête, G. Durocher, M. Leclerc,
Adv. Mater. 1998, 10, 599; b) F. Di Maria, P. Olivelli, M. Gazzano,
A. Zanelli, M. Biasiucci, G. Gigli, D. Gentili, P. D’Angelo,
M. Cavallini, G. Barbarella, J. Am. Chem. Soc. 2011, 133, 8654.
[7] S. J. Evenson, S. C. Rasmussen, Org. Lett. 2010, 12, 4054.
[8] a) M.-C. Chen, S. Vegiraju, C.-M. Huang, P.-Y. Huang,
K. Prabakaran, S. L. Yau, W.-C. Chen, W.-T. Peng, I. Chao,
C. Kim, Y.-T. Tao, J. Mater. Chem. C 2014, 2, 8892; b) M.-C. Chen,
Y.-J. Chiang, C. Kim, Y.-J. Guo, S.-Y. Chen, Y.-J. Liang, Y.-W. Huang,
T.-S. Hu, G.-H. Lee, A. Facchetti, T. J. Marks, Chem. Commun. 2009,
1846; c) S. Vegiraju, D.-Y. Huang, P. Priyanka, Y.-S. Li, X.-L. Luo,
S.-H. Hong, J.-S. Ni, S.-H. Tung, C.-L. Wang, W.-C. Lien, S. L. Yau,
C.-L. Liu, M.-C. Chen, Chem. Commun. 2017, 53, 5898; d) C. Kim,
M.-C. Chen, Y.-J. Chiang, Y.-J. Guo, J. Youn, H. Huang, Y.-J. Liang,
Y.-J. Lin, Y.-W. Huang, T.-S. Hu, G.-H. Lee, A. Facchetti, T. J. Marks,
Org. Electron. 2010, 11, 801.
[9] a) B. R. Beno, K.-S. Yeung, M. D. Bartberger, L. D. Pennington,
N. A. Meanwell, J. Med. Chem. 2015, 58, 4383; b) M. Turbiez,
P. Frère, M. Allain, N. Gallego-Planas, J. Roncali, Macromolecules
2005, 38, 6806; c) M. A. Uddin, T. H. Lee, S. Xu, S. Y. Park, T. Kim,
S. Song, T. L. Nguyen, S.-J. Ko, S. Hwang, J. Y. Kim, H. Y. Woo,
Chem. Mater. 2015, 27, 5997.
[10] L. Huang, H. Li, Acta Crystallogr., Sect. E: Struct. Rep. Online 2011,
67, o3512.
[11] a) H. A. Becerril, M. E. Roberts, Z. Liu, J. Locklin, Z. Bao, Adv. Mater.
2008, 20, 2588; b) G. Giri, E. Verploegen, S. C. B. Mannsfeld,
S. Atahan-Evrenk, D. H. Kim, S. Y. Lee, H. A. Becerril,
A. Aspuru-Guzik, M. F. Toney, Z. Bao, Nature 2011, 480, 504;
c) Y. Diao, B. C. K. Tee, G. Giri, J. Xu, D. H. Kim, H. A. Becerril,
R. M. Stoltenberg, T. H. Lee, G. Xue, S. C. B. Mannsfeld, Z. Bao,
Nat. Mater. 2013, 12, 665.
[12] a) R. J. Kline, D. M. DeLongchamp, D. A. Fischer, E. K. Lin,
L. J. Richter, M. L. Chabinyc, M. F. Toney, M. Heeney, I. McCulloch,
Macromolecules 2007, 40, 7960; b) A. Salleo, R. J. Kline,
D. M. DeLongchamp, M. L. Chabinyc, Adv. Mater. 2010, 22,
3812; c) S. Himmelberger, D. T. Duong, J. E. Northrup, J. Rivnay,
F. P. V. Koch, B. S. Beckingham, N. Stingelin, R. A. Segalman,
S. C. B. Mannsfeld, A. Salleo, Adv. Funct. Mater. 2015, 25, 2616.
[13] J. Li, F. Qin, C. M. Li, Q. Bao, M. B. Chan-Park, W. Zhang, J. Qin,
B. S. Ong, Chem. Mater. 2008, 20, 2057.
[5] a) G. C. Welch, R. C. Bakus, S. J. Teat, G. C. Bazan, J. Am. Chem.
Soc. 2013, 135, 2298; b) H. Bronstein, M. Hurhangee, E. C. Fregoso,
D. Beatrup, Y. W. Soon, Z. Huang, A. Hadipour, P. S. Tuladhar,
S. Rossbauer, E.-H. Sohn, S. Shoaee, S. D. Dimitrov, J. M. Frost,
R. S. Ashraf, T. Kirchartz, S. E. Watkins, K. Song, T. Anthopoulos,
J. Nelson, B. P. Rand, J. R. Durrant, I. McCulloch, Chem. Mater.
2013, 25, 4239; c) N. Hergue, P. Leriche, P. Blanchard, M. Allain,
N. Gallego-Planas, P. Frere, J. Roncali, New J. Chem. 2008, 32,
932; d) Y.-Q. Zheng, T. Lei, J.-H. Dou, X. Xia, J.-Y. Wang, C.-J. Liu,
J. Pei, Adv. Mater. 2016, 28, 7213; e) N. E. Jackson, B. M. Savoie,
K. L. Kohlstedt, M. Olvera de la Cruz, G. C. Schatz, L. X. Chen,
M. A. Ratner, J. Am. Chem. Soc. 2013, 135, 10475; f) Y. Gao,
©
Adv. Mater. 2017, 1702414
1702414 (8 of 8)
2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim