Tetraazabenzodifluoranthene diimides: Building blocks for solution-processable n-type organic semiconductors

Article abstract of DOI:10.1002/anie.201210085

11-Ring heterocyclic diimides were synthesized and found to be planar and to exhibit a slipped face-to-face πstacking. Variation of the substituents tunes the electronic structure and properties. In n-channel organic field-effect transistors, the new organic semiconductors have a high electron mobility. When they were used as acceptor material in polymer solar cells, a power conversion efficiency of 1.8 % was obtained. Copyright

Full text of DOI:10.1002/anie.201210085

Angewandte
Chemie
DOI: 10.1002/anie.201210085
Organic Semiconductors
Tetraazabenzodifluoranthene Diimides: Building Blocks for Solution-
Processable n-Type Organic Semiconductors**
Haiyan Li, Felix Sunjoo Kim, Guoqiang Ren, Emily C. Hollenbeck, Selvam Subramaniyan, and
Samson A. Jenekhe*
Organic electronics, which exploits organic molecular materi-
als as semiconductors and active elements in devices, is
a rapidly growing interdisciplinary field of research. Its
applications include organic field-effect transistors
(OFETs), logic circuits, memories, organic light-emitting
diodes and displays, lighting, and organic photovoltaic devices
(OPVs).[1] Both hole-conducting (p-type) and electron-con-
ducting (n-type) organic semiconductors are required in these
device applications. In the past two decades, considerable
progress has been made in developing p-type organic semi-
conductors of diverse molecular structures, which have
enabled advances in device performance and understanding
of charge transport.[1a,d,f] In contrast, n-type organic semi-
conductors have limited molecular diversity, their device
performance (e.g. electron mobility) is still lower than that of
p-type organic materials, and the understanding of electron
transport is not as good as that of p-type materials.[1c,2]
Current n-type organic semiconductors are roughly of two
types: 1) those obtained by functionalizing known p-type
molecules (e.g. oligothiophenes) with electron-withdrawing
groups;[3] and 2) those constructed from distinct electron-
deficient polycyclic rings as exemplified by naphthalene
diimide (NDI) and perylene diimide (PDI).[4] Functionaliza-
tion with electron-withdrawing groups can efficiently increase
the electron affinity. However, the substituents may reduce
the planarity of the parent molecules because of steric effects;
the distortion from planarity leads to interruption of the p-
electron orbital overlap and can adversely affect charge
transport.[5] Among current n-type organic semiconductors,
naphthalene diimides (NDIs) and perylene diimides (PDIs)
and their derivatives have shown promising electron-trans-
port properties.[4,6]
Scheme 1. Synthesis of BFIs.
We report herein the first examples of heterocyclic
diimides, tetraazabenzodifluoranthene diimides (BFIs); the
synthesis involves fusion of a synthetically tunable tetraaza-
anthracene core and two naphthalene imide units (Scheme 1).
This molecular design aims to: 1) obtain high electron affinity
by combining the electron-deficient imine nitrogen contain-
ing aromatic groups with the dicarboxylic acid imide func-
tionality; 2) form a large rigid ladder-type structure: in
comparison to NDI and PDI, the 11-ring BFI system has an
even larger framework, which can further extend the p con-
jugation, promote intermolecular orbital overlap, and
improve carrier mobilities; 3) potentially tune the optical
and electronic properties through nitrogen protonation or
quaternization;[7] and 4) enable fine-tuning of the electronic
structure, solution processability, and solid-state morphology.
Further molecular modification of the BFIs can either occur
at the imide nitrogen atoms, the “bay” area, or even the
“core” itself. Unlike the sterically crowded NDI and PDI
rings, the new tetraazabenzodifluoranthene diimide has two
[*] Dr. H. Li, Dr. F. S. Kim, G. Ren, E. C. Hollenbeck,
Dr. S. Subramaniyan, Prof. Dr. S. A. Jenekhe
Department of Chemical Engineering and Department of Chemistry
University of Washington
Seattle, WA 98195-1750 (USA)
E-mail: jenekhe@u.washington.edu
[**] We thank Dr. Werner Kaminsky for obtaining the X-ray single crystal
structure of BFI. This work was supported by the NSF (DMR-
1035196), Office of Naval Research (ONR) (N00014-11-1-0317),
and Solvay S. A.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201210085.
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symmetric and easily accessible sites for substitution. We
envision that the new dibromide derivative BFI-Br2 will
become an important intermediate for the design and syn-
thesis of new organic/polymer semiconductors.
Scheme 1 presents the synthesis of BFI and its derivatives.
Starting from acenaphthene (1), the diketo intermediates 2-
(2-hexyldecyl)-1H-indeno[6,7,1-def]isoquinoline-1,3,6,7(2H)-
tetraone and 2-(2-decyltetradecyl)-1H-indeno[6,7,1-def]iso-
quinoline-1,3,6,7(2H)-tetraone (5 and 8) were synthesized in
four steps. 1,2-Diketone is well-known to readily react with
ortho-arylenediamine to form a pyrazine ring.[8] By taking
advantage of this reaction, BFI (6) and BFI-Br2 (9) were
synthesized in the reactions of 5 with 1,2,4,5-benzenetetra-
amine tetrahydrochloride and 8 with 3,6-dibromobenzene-
1,2,4,5-tetraamine, respectively. The reaction of the key
precursor BFI-Br2 with 2-tributylstannylthiophene or 5-
methyl-2-trimethylstannylthiophene under standard Stille
cross-coupling reaction conditions afforded BFI-T2 (com-
pound 10-T2) and BFI-TM2 (compound 10-TM2), respec-
tively. The dicyano derivative BFI-CN2 (10-CN2) was pre-
pared by the reaction of BFI-Br2 with CuCN in DMF. BFI-T2
and BFI-TM2 were isolated as green solids, and BFI-CN2 was
isolated as a yellow solid. The parent BFI has a poor solubility
in aprotic organic solvents, but can be dissolved in organic
acids (e.g. trifluoroacetic acid) or organic solvent/organic acid
solvent mixtures. With two bromo groups, BFI-Br2 has
moderate solubility and can be dissolved in warm organic
solvents. Fortunately, attachment of substituent groups dra-
matically enhances the solubility of the BFI derivatives. BFI-
CN2, BFI-T2, and BFI-TM2 all have good solubility in
organic solvents (chloroform, dichloromethane, toluene, etc.).
Thermogravimetric analysis showed that all the molecules
are thermally stable with high thermal decomposition tem-
peratures (Td ꢀ 4008C; Figure S6 and Table S2 in the Sup-
porting Information). Differential scanning calorimetry
(DSC) showed that the parent BFI (6) has no detectable
phase transitions in the temperature range from 308C to
2508C, whereas BFI-T2, BFI-TM2, and BFI-CN2 each
exhibited multiple melting and liquid-crystalline transitions
(Figure S7 and Table S2 in the Supporting Information). The
high thermal stability of BFI arises from the dense packing of
the large planar backbones and strong intermolecular inter-
actions induced by the polar imide groups and the imine
nitrogen atoms. On the other hand, the substituents on BFI-
CN2, BFI-T2, and BFI-TM2 increase the free space between
the molecular backbones and enable the observed thermal
transitions.
Figure 1. Crystal structure of BFI. a) Thermal ellipsoid plot with ellip-
soids drawn at 50% probability level. b) Face-to-face p–p stacking with
À
an interplanar distance of 3.24 ꢀ. c) C H···O hydrogen bonding
between stacks (dashed lines in red circle).
nitrogen atoms. The neighboring BFI molecules feature
a short vertical distance of 3.24 ꢀ, which is significantly
shorter than the interplanar distance of graphite (3.35 ꢀ)[10]
and suggests strong p–p interactions (Figure 1b). Further-
more, we found that p–p stacking is not the only driving force
that controls the assembly of BFI molecules. Figure 1c shows
À
another type of close contacts, C H···O hydrogen bonds,
which are shorter than the sum of van der Waals radii and
exist between the neighboring stacks. In these hydrogen
bonds, the oxygen atom on the carbonyl group and the ortho-
carbon atom on the naphthalene ring of the neighboring
molecule function as the hydrogen acceptor and donor,
respectively. The H···O distance is measured to be 2.44 ꢀ and
the C-H···O angle to be 140.18. Both the rigid planar structure
and strong intermolecular interactions are highly desirable for
achieving high crystallinity, high degree of molecular orbital
coupling, and efficient carrier transport.
Single-crystal X-ray diffraction analysis of BFI (Figure 1)
showed that the BFI molecules are aligned in a triclinic unit
cell with a = 4.681(4) ꢀ, b = 16.30(2) ꢀ, c = 17.554(16) ꢀ, a =
94.08(5)8, b = 93.92(3)8, g = 95.36(6)8.[9] The polycyclic BFI
ring has a planar geometry involving both the diimide groups
and tetraazabenzodifluoranthene backbone (Figure 1a). The
molecules of BFI form a slipped face-to-face p–p stacking,
and the displacement between two neighboring molecules is
less than one sixth of the length of the molecule; this ratio is
relatively smaller than that of the NDI and PDI molecules,[4d,i]
which might be due to the much longer length of BFI and
stronger intermolecular interactions induced by the imine
X-ray quality single crystals of BFI-T2, BFI-TM2, or BFI-
CN2 could not be obtained under normal solution conditions.
X-ray diffraction (XRD) from solution-cast films was thus
used to evaluate the crystallinity of this series of molecules.
The intense first Bragg reflection and its higher-order
reflections from BFI films were observed at 3.08, 9.38, 12.38,
18.58, and 21.28 corresponding to a d-spacing of 2.9 nm, which
is close to the length of the long axis of the BFI molecules and
thus is assigned to the edge-to-edge packing of the BFI
molecules along the long axis (Figure S8 in the Supporting
Information). BFI-T2 and BFI-TM2 exhibit similar X-ray
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diffraction patterns as BFI, although the reflection angles are
slightly different: the long-axis reflections of BFI-T2 and BFI-
TM2 are observed at 2.98 (d = 3.1 nm) and 3.28 (d = 2.8 nm),
respectively. The 2-thienyl and 5-methyl-2-thienyl groups
significantly enlarge the d-spacing of the short-axis reflec-
tions, which are observed at 7.58 (d = 11.8 ꢀ) for BFI-T2 and
7.48 (d = 11.9 ꢀ) for BFI-TM2 in comparison to that of BFI at
10.58 (d = 8.5 ꢀ). Unlike BFI, BFI-T2, and BFI-TM2 films,
which favor edge-to-edge packing, BFI-CN2 is less crystalline
with two broad peaks at 25.78(d=3.55 ꢀ) and 20.08 (d =
4.50 ꢀ), corresponding to the face-to-face p–p stacking.
Such a substituent-dependent solid-state morphology can be
expected to affect the charge transport properties of these
materials in devices.
Effects of the substituent group on the electronic structure
of BFI molecules were examined by UV/Vis absorption
spectroscopy of BFIs in dilute solution and as thin films. The
absorption maxima, molar absorptivity (emax), absorption
coefficient (amax), and optical absorption edge band gaps are
collected in Table S2 in the Supporting Information. In
solution (Figure 2a), all the BFIs show a common high-
energy absorption band centered at around 400 nm with emax
of (1.0–1.7) ꢁ 105 mÀ1 cmÀ1, which is thus assigned to the
transition characteristic of the tetraazabenzodifluoranthene
diimide chromophore. A new low-energy band appears in the
region of 460–700 nm (emax = (1.3–1.8) ꢁ 104 mÀ1 cmÀ1) for both
BFI-T2 and BFI-TM2, which is consistent with the facts that
BFI and BFI-CN2 are yellow, whereas BFI-T2 and BFI-TM2
are green in color. The observed low-energy absorption band
in BFI-T2 and BFI-TM2, which is absent in BFI and BFI-
CN2, originates from intramolecular charge transfer between
the electron-deficient BFI and electron-donating thiophene
or methylthiophene substituents.[11] Going from dilute solu-
tion to thin films (Figure S9 in the Supporting Information),
the high-energy absorption band is blue-shifted by 20–40 nm
suggesting an H aggregation in the solid state. In contrast, the
lower-energy absorption of BFI-T2 and BFI-TM2 becomes
significantly red shifted (ca. 100 nm), which could be under-
stood as a result of enhanced intramolecular charge transfer
enabled by the strong intermolecular interactions.[11] BFI and
BFI-CN2 have energy gaps of 2.43–2.50 eV, whereas BFI-T2
and BFI-TM2 have a significantly narrower band gap of
1.6 eV. We note that the band gap of BFI-T2 and BFI-TM2 is
about 0.46 eV narrower than that of the NDI analogue (NDI-
1TH),[4d] thus suggesting a higher degree of electron delocal-
ization. The absorption coefficient (amax) at the higher-energy
absorption maximum of the thin films varied from 6.7 ꢁ
104 cmÀ1 in BFI-T2 to 1.4 ꢁ 105 cmÀ1 in BFI-CN2, which is
indicative of strongly absorbing chromophores.
Figure 2b shows the thin-film cyclic voltammograms of
the BFI molecules in acetonitrile with tetrabutylammonium
hexafluorophosphate as the electrolyte (0.1m). BFI shows two
quasi-reversible reduction waves at E1/2 = À0.80 V/À1.20 V,
whereas the reduction peaks of BFI-T2 and BFI-TM2 are
seen at more negative potentials of E1/2 = À1.10 V/À1.35 V
and À1.23 V (peak), respectively. As expected, BFI-CN2,
with two strong electron-withdrawing cyano groups attached,
is reduced at much higher potentials with three reversible
waves at E1/2 = À0.34 V/À0.46 V/À0.75 V. Accordingly, the
resulting estimate of the lowest unoccupied molecular orbital
(LUMO) energy level of BFI-CN2 is À4.32 eV, which is about
0.6–0.8 eV lower than that of BFI, BFI-T2, and BFI-TM2 and
0.4–0.6 eV lower than that of NDI and PDI.[4f] CV scans
showed that BFIs either had a very weak oxidation or did not
show any oxidation up to 1.2 V, indicative of a rather deep
lying highest occupied molecular orbital (HOMO) energy
level.
OFETs with bottom-gate geometry were fabricated by
solution deposition of thin films to investigate the polarity and
field-effect mobility of charge carriers in the BFIs. All the
BFIs were found to exhibit n-channel charge transport
characteristics in OFETs, thereby giving moderate to high
electron mobilities (me) of 0.021 to 0.12 cm2 VÀ1 sÀ1 in the
saturation region and excellent on/off current modulation
(105–106; Figure 3 and Figures S10 and S11 in the Supporting
Information). Among them, BFI-T2 thin films had the highest
carrier mobility of me = 0.12 cm2 VÀ1 sÀ1 (Figure 3 and Fig-
ure S12 in the Supporting Information). The average field-
effect electron mobilities of the parent BFI and BFI-TM2
were 0.03 cm2 VÀ1 sÀ1 and 0.05 cm2 VÀ1 sÀ1, respectively.
Although BFI-CN2 has a higher electron affinity, it has the
lowest electron mobility of 0.021 cm2 VÀ1 sÀ1 in the transistors,
which can be attributed to its poorer solid state packing as
revealed by previously discussed XRD analysis. The BFIs
Figure 2. a) UV/Vis absorption spectra of BFIs in dilute solution (1.4–
3.4 mm). b) Cyclic voltammograms of BFI molecules with the ferro-
cene/ferrocenium (Fc/Fc+) couple as the internal reference. SCE=sa-
turated calomel electrode. c) HOMO/LUMO energy levels of BFI
molecules.
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ure 4b) shows that the photoresponse begins near 800 nm, an
important demonstration that the new electron acceptor can
harvest photons from the near-IR region of the solar
spectrum. The EQE spectrum has peaks of 31% at 370 nm
and 28% at 630 nm. The Jsc value calculated by integrating
the EQE spectrum is 4.85 mAcmÀ2, which is within 6.0% of
the directly measured value. These preliminary results
demonstrate that the BFIs are promising small-molecule,
nonfullerene, acceptor materials for organic photovoltaics.
In conclusion, we have successfully created new hetero-
cyclic diimides as building blocks for developing n-type
organic semiconductors. The X-ray single-crystal structure
shows that tetraazabenzodifluoranthene diimide has a ladder-
type planar conformation, which facilitates desirable solid-
state molecular packing. The symmetric substitution sites on
the core BFI framework provide a means for fine-tuning the
electronic structure, solid-state morphology, and properties of
the new class of n-type organic semiconductors. The BFIs
combine large electron affinities (3.6–4.3 eV) with attractive
optical band gaps of 2.5–1.6 eV by varying the substituents at
the core position. Preliminary n-channel OFETs and BHJ
solar cells based on solution-processed thin films gave an
electron mobility of 0.12 cm2 VÀ1 sÀ1 and a power conversion
efficiency of 1.8%, respectively, and thus demonstrated that
the BFIs are promising n-type materials for organic elec-
tronics and nonfullerene photovoltaics. Indeed, BFI-T2 is the
first nonfullerene small molecule that combines both high
electron mobility in solution-processed n-channel OFETs and
high power conversion efficiency as an electron acceptor in
BHJ solar cells.
Figure 3. Transfer curve of a) BFI-T2 transistors after annealing at
1508C (Vds =80 V). b) Electron mobilities of the BFIs measured in
nitrogen as a function of annealing temperatures. Ids =drain current,
Vgs =gate voltage, Vds =drain voltage.
showed an annealing temperature dependence of the electron
mobility (Figure 3b). Annealing at 1508C gave the highest
mobility in accord with expectation from the DSC results. We
note that the electron mobility derived from the linear region
was generally 2–7-fold lower than the saturation mobility
(Table S3 in the Supporting Information). Moderate thresh-
old voltage (17–32 V) and hysteresis in forward and backward
scans were also observed from the transistors (Figure S11 in
the Supporting Information), possibly owing to traps at
interfaces. The threshold voltage and the hysteresis, as well as
the electron mobility could be significantly improved by
interfacial engineering and optimization of device fabrica-
tion.[1]
In a preliminary evaluation of the potential of the BFIs to
function as an electron acceptor in bulk heterojunction (BHJ)
solar cells, we fabricated and tested devices of the type ITO/
PEDOT:PSS/PSEHTT:BFI-T2(1:4 wt/wt)/LiF/Al under AM
1.5 solar illumination at 1 sun (100 mWcmÀ2) in ambient air
[ITO = indium tin oxide, PEDOT= poly(3,4-ethylenedioxy-
thiophene), PSS = poly(styrenesulfonate)]. The donor poly-
mer PSEHTT is a reported ethylhexyl derivative of thiazo-
lothiazole copolymer.[12] The current density (J)–voltage (V)
curves for these devices are shown in Figure 4a. The resulting
photovoltaic parameters include an open circuit voltage (Voc)
of 0.79 V, a short-circuit current density (Jsc) of 5.14 mAcmÀ2,
and a fill factor (FF) of 0.44. A maximum power conversion
efficiency of 1.80% (average of 1.74 Æ 0.06%) was achieved.
The EQE spectrum of the PSEHTT:BFI-T2 devices (Fig-
Received: December 18, 2012
Revised: March 17, 2013
Published online: && &&, &&&&
Keywords: electron transport · energy conversion ·
.
field-effect transistors · semiconductors · solar cells
[1] a) C. Wang, H. Dong, W. Hu, Y. Liu, D. Zhu, Chem. Rev. 2012,
112, 2208; b) A. Mishra, P. Bꢂuerle, Angew. Chem. 2012, 124,
2060; Angew. Chem. Int. Ed. 2012, 51, 2020; c) H. Usta, A.
Facchetti, T. J. Marks, Acc. Chem. Res. 2011, 44, 501; d) F. S.
Kim, G. Ren, S. A. Jenekhe, Chem. Mater. 2011, 23, 682; e) A. R.
Murphy, J. M. J. Frꢃchet, Chem. Rev. 2007, 107, 1066; f) S.
Allard, M. Forster, B. Souharce, H. Thiem, U. Scherf, Angew.
Chem. 2008, 120, 4138; Angew. Chem. Int. Ed. 2008, 47, 4070;
g) F. Wꢄrthner, Angew. Chem. 2001, 113, 1069; Angew. Chem.
Int. Ed. 2001, 40, 1037; h) A. Facchetti, Chem. Mater. 2010, 23,
733.
[2] a) J. E. Anthony, A. Facchetti, M. Heeney, S. R. Marder, X.
Zhan, Adv. Mater. 2010, 22, 3876; b) Y. Wen, Y. Liu, Adv. Mater.
2010, 22, 1331; c) J. Zaumseil, H. Sirringhaus, Chem. Rev. 2007,
107, 1296; d) C. R. Newman, C. D. Frisbie, D. A. da Silva Filho,
J.-L. Brꢃdas, P. C. Ewbank, K. R. Mann, Chem. Mater. 2004, 16,
4436; e) C. J. Tonzola, M. M. Alam, W. Kaminsky, S. A. Jenekhe,
J. Am. Chem. Soc. 2003, 125, 13548; f) A. Babel, S. A. Jenekhe, J.
Am. Chem. Soc. 2003, 125, 13656.
Figure 4. a) J–V characteristics of a PSEHTT:BFI-T2 (1:4 wt/wt) blend
solar cell and b) the corresponding external quantum efficiency (EQE)
spectrum.
[3] a) F. Babudri, G. M. Farinola, F. Naso, R. Ragni, Chem.
Commun. 2007, 1003; b) M.-H. Yoon, S. A. DiBenedetto, A.
Facchetti, T. J. Marks, J. Am. Chem. Soc. 2005, 127, 1348; c) A.
4
www.angewandte.org
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Angew. Chem. Int. Ed. 2013, 52, 1 – 6
These are not the final page numbers!

Angewandte
Chemie
Facchetti, M. Mushrush, M.-H. Yoon, G. R. Hutchison, M. A.
Ratner, T. J. Marks, J. Am. Chem. Soc. 2004, 126, 13859.
Ed. 2010, 49, 740; c) R. Schmidt, J. H. Oh, Y.-S. Sun, M.
Deppisch, A.-M. Krause, K. Radacki, H. Braunschweig, M.
Kçnemann, P. Erk, Z. Bao, F. Wꢄrthner, J. Am. Chem. Soc. 2009,
131, 6215.
[4] a) X. Guo, F. S. Kim, M. J. Seger, S. A. Jenekhe, M. D. Watson,
Chem. Mater. 2012, 24, 1434; b) J. L. Segura, H. Herrera, P.
Bꢂuerle, J. Mater. Chem. 2012, 22, 8717; c) F. Wꢄrthner, M.
Stolte, Chem. Commun. 2011, 47, 5109; d) E. Ahmed, G. Ren,
F. S. Kim, E. C. Hollenbeck, S. A. Jenekhe, Chem. Mater. 2011,
23, 4563; e) L. E. Polander, S. P. Tiwari, L. Pandey, B. M.
Seifried, Q. Zhang, S. Barlow, C. Risko, J.-L. Brꢃdas, B.
Kippelen, S. R. Marder, Chem. Mater. 2011, 23, 3408; f) X.
Zhan, A. Facchetti, S. Barlow, T. J. Marks, M. A. Ratner, M. R.
Wasielewski, S. R. Marder, Adv. Mater. 2011, 23, 268; g) F. S.
Kim, X. Guo, M. D. Watson, S. A. Jenekhe, Adv. Mater. 2010, 22,
478; h) H. Yan, Z. Chen, Y. Zheng, C. Newman, J. R. Quinn, F.
Dotz, M. Kastler, A. Facchetti, Nature 2009, 457, 679; i) A. L.
Briseno, S. C. B. Mannsfeld, C. Reese, J. M. Hancock, Y. Xiong,
S. A. Jenekhe, Z. Bao, Y. Xia, Nano Lett. 2007, 7, 2847; j) H. E.
Katz, A. J. Lovinger, J. Johnson, C. Kloc, T. Siegrist, W. Li, Y. Y.
Lin, A. Dodabalapur, Nature 2000, 404, 478.
[6] a) S.-L. Suraru, U. Zschieschang, H. Klauk, F. Wꢄrthner, Chem.
Commun. 2011, 47, 11504; b) Y. Zhao, C.-A. Di, X. Gao, Y. Hu,
Y. Guo, L. Zhang, Y. Liu, J. Wang, W. Hu, D. Zhu, Adv. Mater.
2011, 23, 2448; c) Y. Avlasevich, C. Li, K. Mꢄllen, J. Mater.
Chem. 2010, 20, 3814.
[7] D. Izuhara, T. M. Swager, J. Am. Chem. Soc. 2009, 131, 17724.
[8] Y. Zhu, C.-T. Yen, S. A. Jenekhe, W.-C. Chen, Macromol. Rapid
Commun. 2004, 25, 1829.
[9] CCDC 915892 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.
cam.ac.uk/data_request/cif.
[10] A. Hꢃrold in Physics of Intercalation Compounds (Eds.: L.
Pietronero, E. Tosatti), Springer, Berlin, 1981, p. 7.
[11] a) S. A. Jenekhe, L. D. Lu, M. M. Alam, Macromolecules 2001,
34, 7315; b) Y. Zhu, R. D. Champion, S. A. Jenekhe, Macro-
molecules 2006, 39, 8712.
[5] a) R. P. Ortiz, H. Herrera, C. Seoane, J. L. Segura, A. Facchetti,
T. J. Marks, Chem. Eur. J. 2012, 18, 532; b) M. Gsꢂnger, J. H. Oh,
M. Kçnemann, H. W. Hçffken, A.-M. Krause, Z. Bao, F.
Wꢄrthner, Angew. Chem. 2010, 122, 752; Angew. Chem. Int.
[12] S. Subramaniyan, H. Xin, F. S. Kim, S. Shoaee, J. R. Durrant,
S. A. Jenekhe, Adv. Energy Mater. 2011, 1, 854.
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Communications
Organic Semiconductors
11-Ring heterocyclic diimides were syn-
thesized and found to be planar and to
exhibit a slipped face-to-face p stacking.
Variation of the substituents tunes the
electronic structure and properties. In n-
channel organic field-effect transistors,
the new organic semiconductors have
a high electron mobility. When they were
used as acceptor material in polymer
solar cells, a power conversion efficiency
of 1.8% was obtained.
H. Li, F. S. Kim, G. Ren, E. C. Hollenbeck,
S. Subramaniyan,
S. A. Jenekhe*
&&&& — &&&&
Tetraazabenzodifluoranthene Diimides:
Building Blocks for Solution-Processable
n-Type Organic Semiconductors
6
www.angewandte.org
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2013, 52, 1 – 6
These are not the final page numbers!