conceptual idea for designing solution processed organic semi-
conductors capable of forming highly ordered thin films in
large areas.
This work is supported by National Basic Research Program
of China (973 Project, No. 2009CB623603) of Chinese Ministry
of Science and Technology, NSFC (No. 20921061 and
50833004).
Notes and references
ꢀ
z Crystal data: C28
32 4
H S , M = 496.76, triclinic, space group P1, a =
.8660(7) A, b = 7.5451(9) A, c = 56.721(7) A, a = 91.309(2)1, b =
˚
˚
˚
5
9
1
3
˚
1.191(2)1, g = 90.093(2)1, V = 2509.2(5) A , T = 185(2) K, Z = 4,
2 251 reflections measured, 8584 unique (Rint = 0.0261). R = 0.1367,
1
2
wR = 0.3014. CCDC 863201.
1
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Fig. 5 The top-contact device geometries (a). (b) The photographic
image of an OTFT device. The width and length of the channel are 1500
and 50 mm, respectively. Typical output (c) and transfer (d) curves of the
OTFTs.
2
3
4
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crystal films. In contrast, DTBDT-C9 and condensed benzo-
17
20
thiophene derivative adopt a 1D p–p stacking motif in the
crystals and the thin film prepared by dip-coating shows a rod or
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Fig. 5a were fabricated on the entrained single crystal films by
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0 (a) Y. Zhou, T. Lei, L. Wang, J. Pei, Y. Cao and J. Wang, Adv.
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(
Fig 5b). Since BTTT-T-C12 exhibits a deep highest occupied
molecular orbital (HOMO) energy level at ꢀ5.57 eV as
(
c) R. Li, L. Jiang, Q. Meng, J. Gao, H. Li, Q. Tang, M. He,
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2
1
ESIw), the F16CuPc/CuPc buffer layer was used in order to
reduce the contact resistance. At least 6 devices were fabri-
cated for confirming the reliability. Device performance
measurements were done in an ambient atmosphere. The typical
output and transfer curves of the devices are shown in Fig. 5c
and d, and the mobility was calculated from the saturation
regime. For the devices with the channel length along the
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1
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2
ꢀ1 ꢀ1
dip-coating direction, a mobility of 0.6–0.7 cm V
threshold voltage of ꢀ10 to ꢀ15 V and a current on/off ratio of
s with a
1
29, 2224.
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5
0 was achieved. The mobility perpendicular to the dip-coating
1
2
direction was 0.2–0.3 cm V
ꢀ1 ꢀ1
s , one third of that along the
dip-coating direction. It is found that a non-linear drain current
increases at a low-drain voltage even with the F16CuPc/CuPc
buffer layer. A similar phenomenon was also observed in other
1
7 L. Li, P. Gao, K. C. Schuermann, S. Ostendorp, W. Wang, C. Du,
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¨
1
0a,b,22
18 L. Jiang, H. Dong, Q. Meng, H. Li, M. He, Z. Wei, Y. He and
W. Hu, Adv. Mater., 2011, 23, 2059.
SCOFETs.
at the metal/organic-semiconductors interface
resistance of the films itself from the metal to the conductive
This should be ascribed to the injection barrier
10a,b
or the high
1
9 (a) E. Menard, A. Marchenko, V. Podzorov, M. E. Gersherson,
D. Fichou and J. A. Rogers, Adv. Mater., 2006, 18, 1552;
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Appl. Phys. Lett., 2009, 95, 093302.
22
channel.
In conclusion, we have shown that the single crystal film with
lateral dimensions of several millimetres can be prepared from a
highly asymmetric conjugated oligomer by a dip-coating method.
2
2
2
0 N. Liu, Y. Zhou, L. Wang, J. Peng, J. Wang, J. Pei and Y. Cao,
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2
ꢀ1 ꢀ1
A high mobility of 0.7 cm V
s along with the high current
on/off ratio has been realized with a device structure generally
used in solution processed OTFTs. These results provide a
(b) L. Jiang, W. Hu, Z. Wei, W. Xu and H. Meng, Adv. Mater.,
2009, 21, 3649.
This journal is c The Royal Society of Chemistry 2012
Chem. Commun., 2012, 48, 3557–3559 3559