Structural Polymorphism and Thin Film Transistor Behavior in the Fullerene Framework Molecule 5,6;11,12-di-o-Phenylenetetracene

Article abstract of DOI:10.1002/anie.201601517

The molecular structure of the hydrocarbon 5,6;11,12-di-o-phenylenetetracene (DOPT), its material characterization and evaluation of electronic properties is reported for the first time. A single-crystal X-ray study reveals two different motifs of intramo

Full text of DOI:10.1002/anie.201601517

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International Edition: DOI: 10.1002/anie.201601517
German Edition: DOI: 10.1002/ange.201601517
Conjugated Polycycles
Structural Polymorphism and Thin Film Transistor Behavior in the
Fullerene Framework Molecule 5,6;11,12-di-o-Phenylenetetracene
Tobias Wombacher, Andrea Gassmann, Sabine Foro, Heinz von Seggern, and Jçrg J. Schneider*
Abstract: The molecular structure of the hydrocarbon
5,6;11,12-di-o-phenylenetetracene (DOPT), its material char-
acterization and evaluation of electronic properties is reported
for the first time. A single-crystal X-ray study reveals two
different motifs of intramolecular overlap with herringbone-
type arrangement displaying either face-to-edge or co-facial
face-to-face packing depicting intensive p–p interactions.
Density functional theory (DFT) calculations underpin that
a favorable electronic transport mechanism occurs by a charge
hopping process due to a p-bond overlap in the DOPT
polymorph with co-facial arene orientation. The performance
of polycrystalline DOPT films as active organic semiconduct-
ing layer in a state-of-the-art organic field effect transistor
(OFET) device was evaluated and proves to be film thickness
dependent. For 40 nm layer thickness it displays a saturation
hole mobility (mhole) of up to 0.01 cm2 VÀ1 sÀ1 and an on/off-
ratio (Ion/Ioff) of 1.5 ” 103.
Figure 1. Left: Superordinated structure of 5,6;11,12-di-o-phenylene-
tetracene (DOPT, 2) as found in e.g., the D2d isomer of the geodesic
fullerene C84. Right: Illustration of the all-planar cruciform structure of
DOPT.
tetracene, 5,6,11,12-tetraphenyltetracenerubrene, or the di-o-
phenylene substituted anthracene molecule rubicene.[2]
Although, reported earlier in elusive experimental work[3]
it was only very recently, that DOPT 2 was made accessible by
Murata[4] and our group[5] in two independent and straightfor-
ward high yield synthetic approaches. Murata et al. presented
a general approach towards cyclo-pentafused polycyclic
aromatics including DOPT-derivatives starting from the
5,11-diaryl-tetracene framework.[4] Shortly after, we were
able to devise a gram-scale synthesis based on well established
Diels–Alder chemistry for the parent molecule DOPT
introducing a so far unprecedented reductive double phenyl
elimination.[5] Highly condensed PAH molecules like DOPT
with their oftentimes energetically favorable molecular
orbital ordering with small electronic band gap differences
excel themselves as promising semiconducting organic mate-
rials for controlled charge transport. The afore mentioned
close structural relationship of DOPT to the polyacene
aromatic family especially the parent tetracene might promise
interesting functional properties applicable in organic elec-
tronics like thin film transistors or future solar energy
harvesting devices.[6]
T
he carbon framework in the title molecule is found as
a basic structural motif in the fullerene molecules C78, C82 and
C84 (Figure 1). In addition, other symmetrical geodesic full-
erene isomers bearing isolated pentagonal ring structures
display molecular units of this conjugated polycycle.
5,6;11,12-di-o-phenylenetetracene (DOPT; 2) belongs to
the class of tetracene derivatives which have spurred interest
over the last decade as model compounds with respect to an
understanding of their chemistry as well as of their electronic
properties like electronic structure and charge transport
ability.[1,2] In the group of cyclo-pentafused polycyclic aro-
matic hydrocarbons (PAH) 2 represents a prototypical acene
framework molecule with peri-substitution closely related to
[*] Dipl.-Ing. T. Wombacher, Prof. Dr. J. J. Schneider
Eduard-Zintl-Institut für Anorganische und Physikalische Chemie,
Technische Universität Darmstadt
Alarich-Weiss-Strasse 12, 64287 Darmstadt (Germany)
E-mail: joerg.schneider@ac.chemie.tu-darmstadt.de
From a synthetic point of view the acene molecule DOPT
is highly stable under ambient conditions when compared to
other substituted tetracene derivatives. This is understandable
when applying the Clar aromatic sextet model which states
that a molecule with more benzenoid sextet moieties
increases its aromatic stabilization energy.[7] Moreover the
fact that DOPT 2 is able to accept at least up to two
electrons[4,5] manifests its high electron affinity and makes it
potentially suited for organic semiconductor applications. In
this regard it falls into the same class of electroactive
molecules as indenofluorenes, emaraldicenes or (silylethyny-
lated) extended p-systems which have been proven as
electron accepting as well as ambipolar molecules in organic
Dr. A. Gassmann, Prof. H. von Seggern
Institut für Material- und Geowissenschaften, Technische Universität
Darmstadt, Fachgebiet Elektronische Materialeigenschaften
Alarich-Weiss-Strasse 2, 64287 Darmstadt (Germany)
S. Foro
Institut für Material- und Geowissenschaften, Technische Universität
Darmstadt, Fachgebiet Strukturforschung (Germany)
Supporting information (thermogravimetric analysis-mass spec-
trometry (TG-MS) and cyclovoltammetric (CV) data of 2, mass
spectrometric (MS) data of 2 recovered from the as-fabricated OFET
units, XPS spectra of 5, 10, 20 and 40 nm films of 2 on SiO2, and
crystal structure parameters of both polymorphs of 2) and the ORCID
identification number(s) for the author(s) of this article can be found
under http://dx.doi.org/10.1002/anie.201601517.
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photovoltaics and organic field effect transistor applica-
tions.[1a,8] Furthermore, such large size PAH molecules have
the capability of coordinating transition metals onto their p-
perimeter framework giving access to organometallics acting
as electroactive molecules which can carry up to four
molecules of redox active metal fragments.[9] Additionally,
such extended p-perimeters show a remarkably high electron
affinity when exposed to strong reductive conditions, in turn
leading to highly charged polyanions accompanied by
a change in the structural shape of the particular neutral
PAH.[10] Herein we report on the single crystal structure and
thin film crystal orientation and phase formation of the title
compound 2 as well as on its electronic properties as studied
by experiment and density functional calculations (DFT).
Finally, we give evidence towards the dependence of its
electronic thin film transistor properties on the deposited film
density. According to our finding, reductive elimination of
two phenyl rings from the dihydrotetracene derivative 5,12-
diphenyl-5,6;11,12-di-o-phenylene-5,12-dihydrotetracenep-
seudorubrene) 1 under re-aromatization has yielded DOPT 2
in high yield on a gram scale.[5]
As an extension of these studies we now report on the
molecular structure of 2. We have found that it crystallizes at
least in two polymorphic crystal arrangements depending on
the crystallization procedures employed. Growth from a con-
centrated tetrahydrofuran or toluene solution gives single
crystals of DOPT which crystallize in space group C 2/c,
whereas slow thermal gradient sublimation gives deep blue,
primitive monoclinic crystals of space group P 21/n (see
Supporting Information).
Figure 2. ORTEP plot of 2 with ellipsoids drawn at 50% probability
level. The tetracenic backbone of 2 is fully planar. The plane of the two
orthogonal phenylene rings deviate only by <18 from planarity towards
the plane of the tetracene ring system. Polymorph P 21/n (b) displays
a herringbone structure with edge-to-face interactions of the DOPT
molecules whereas polymorph C 2/c shows a co-facial herringbone
arrangement with characteristic face-to-face p-interactions of neighbor-
ing DOPT molecules within the unit cell.
Thus, we speculated that the observed difference in the
molecular arrangement of DOPT in the crystalline state
might enable different charge-transport properties. As
reported e.g., for tetracene,[11–13] rubrene,[13] rubicene[8f, 14] or
pentacene,[11b,15a,16] 2 adopts the well established herringbone-
type structure orientation of individual molecules in the
crystalline state (Figure 2). However, significant differences
within the particular degree of the observed p-stacking are
found in both polymorphs of 2. Both monoclinic polymorphs
of 2 consist of two sets of parallel aligned layers of DOPT
molecules with different dihedral angles between two DOPT
molecules (P 21/n polymorph: 848; polymorph C 2/c: 648). The
p-framework of individual molecules of 2 is almost flat and
displays a double cross-conjugation of the acene and the peri-
condensed phenylene moieties as derived from the observed
of the two staggered p-systems is observed, resulting in an
overall denser packing of staggered DOPT layers in this
polymorph (e.g. 1calcd(P 21/n) = 1.387 gcmÀ3 < 1calcd(C 2/c) =
1.412 gcmÀ3) (Figure 3).
The tetracenic core and the peripheric phenylene rings of
staggered 2 are in close contact displaying distances of 349
and 356 pm, respectively. These findings for 2 are in line with
structural motifs found for reported polymorphs of the parent
tetracene molecule,[12,13] the tetracene derivative rubrene[13,17]
or for higher homologue pentacene[16] as well as other related
structures.[8i]
As gas phase deposition of PAHs most often leads to
a typical herringbone orientation with edge-to-face packing, it
was surprising that indeed vacuum deposited films of 2
exclusively reveal the C 2/c polymorph when deposited on Si/
SiO2 substrate (see GIXRD, Figure 4). The C 2/c slipped p-
stacking motive of 2 favors a better face-to-face overlap
compared to the edge-to-face arrangement with its nearly
orthogonal p–p stacked orientation of two DOPT molecules.
In contrast to the P 21/n phase obtained when 2 is
sublimed onto a glass surface (calcd: 11.05, 16.24, 25.508 2q),
the major reflections at 8.10/16.358 2q in GIXRD experiments
give distinct evidence for the full staggered packing mode
(calcd: 8.18, 16.40, 24.418 2q; exp: 8.08, 16.3088 2q) of 2 in C 2/c.
The preferred growth of the polymorphic orientation of 2 on
Si/SiO2 might be due to a substrate induced epitaxial re-
orientation as found for rubicene and has been nicely shown
by Winkler et al.[14] Crystalline 2 obtained from solution as
well as from the gas phase indeed reveals strong anisotropic
À
C C bond-length alternation (Figure 2a). The observed
intramolecular overlap between adjacent molecules of
DOPT within the parallel stacked layer enables an electronic
interplay of the HOMO–LUMO p-orbitals by [p–p]- and
[C–H·p]-interactions necessary for an efficient charge trans-
port within the stack.[2,15]
For the P 21/n phase of 2 the distance d(p–p)core between
two staggered molecules of DOPTA and DOPTB is smallest
for C8A–C2’B with 345 pm which compares nicely to the
interplanar distance of 338 pm between two adjacent mole-
cules in rubicene crystals of space group P 21/n.[14] The peri-
coordinated phenylene units in 2 exhibit a closest distance
d(p–p)peri to neighboring molecules by 368 pm for C14A–
C11’B. In contrast, for the C 2/c-phase a nearly full p-overlap
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Figure 3. Illustration of the orientation and intermolecular distance
between two individual molecules DOPT A and DOPT B in both
monoclinic polymorphs. Dot size in (a) and (c) inversely corresponds
À
to C C distance of carbon atoms in adjacent DOPT molecules. The
À
largest CA CB distance is highlighted with the smallest dot. For the
À
P 21/n polymorph (a), a displacement by two C C bonds compared to
the C 2/c type (b) is observed, resulting in a distinctively increased
face-to-face p-stacking for the latter.
Figure 5. AFM topographic images obtained for film heights h:
a) 5 nm, b) 10 nm, c) 20 nm, d) 40 nm of 2 (white bars indicate scan
direction). All deposited films consist of randomly oriented thin
needles of ca. 1 mm in length. With increasing DOPT layer thickness
enhanced crystal overlap and compacted packing is observed.
to two microns in length. Depending on the deposition
thickness the needle-like thin film thickness increases con-
siderably (Figure 5a–d). Due to the observed film morphol-
ogy the growth mechanism of 2 is in full accordance with
observations on film growth of closely related rubicene on Si/
SiO2 substrate.[14] Thus, mainly Ostwald ripening of the
initially adsorbed molecules leads to an anisotropic island
growth of crystals of 2 preventing the development of
a homogeneous thin film. Furthermore, we analyzed all thin
films of 2 by UV/Vis transmission mode in order to correlate
the absorption spectra to the varying film thickness (5, 10, 20,
and 40 nm) (Figure 6) and to validate evidence of the so far
observed structural ordering what has also an effect on the
electronic behavior.[18]
Figure 4. a) XRD pattern of microcrystalline DOPT 2 obtained from
solution and after grinding; b) GIXRD pattern with a cartoon showing
the face-to-face interaction of individual molecules in a thin film of
vacuum deposited crystalline 2 on Si/SiO2(*); c) calculated spectra
showing all possible reflections (lower trace).
texturing effects resulting in significant diminution of higher
order reflections for both polymorphs in XRD and GIXRD
(Figure 4). This effect could be verified by strong mechanical
grinding of a crystalline sample of 2. This generates the
missing higher order reflections due to a sample homoge-
nization (see Supporting Information).
Compared to the UV/Vis spectra obtained from CHCl3
solution, a J-aggregation[19] is observed and manifests itself by
a strong bathochromic shift (+63 nm) to longer wavelength
(lmax (l)[5]/ lmax (s),40 nm: 607.5/670.5 nm).
In order to understand the substrate influence better, the
morphology of vacuum deposited DOPT films was evaluated
for 5, 10, 20 and 40 nm layers of 2 by atomic force microscopy
(AFM, Figure 5). All macroscopic homogeneously appearing
films are composed of randomly distributed thin needles of up
DFT calculations on B3LYP/6-31G**[20] level give the
frontier orbital energy of the participating HOMO/LUMO
orbitals of DOPT and reveal a significantly enhanced orbital
overlap for the face-to-face p-stacking mode of the C 2/c
compared to the P 21/n polymorph (Figure 7). The exper-
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Vis spectra (Figure 6). Cyclic voltammetry (CV) of 2 reveals
a quasi-reversible (0/À1) reduction at À1.22 V (DEp = 80 mV)
red
1=2
and a reversible reduction (À1/À2) at E À1.65 V (DEp =
60 mV) which is in full agreement with our earlier proposed
synthetic pathway leading to the formation of 2.[5] Due to
ox
1=2
a lack of a reversible oxidation event E (0/+1) for 2 up to
+ 1.0 V no direct determination of the corresponding band
gap DE is possible. However, the LUMO energy of 2 is
Figure 6. a) UV/Vis-spectra of 2 in CHCl3 solution and b) in solid films
of different thickness (h=5, 10, 20, 40 nm). Eg,opt is reduced from
ꢀ1.86 eV in solution down to ꢀ1.70 eV in the solid state. A strong
bathochromic shift (+63 nm) due to J-aggregation effects is observed
for the absorption at longer wavelength (607.5!670.5 nm).[19]
estimated to be À3.10 V (using Er0e=dÀ1 = À1.22 V), respectively
red
À2.67 V (using E
ELUMO(DOPT)
= À1.65 V) according to the equation
À1=À2
=
ox
1=2
À[Ered(DOPT)- E (Fc/Fc+)]ÀEHOMO
-
(Fc)[21] (see Supporting Information). Both values correspond
well with the calculated energy of ELUMO(DOPT) of À2.88 eV
(Figure 7a). The HOMO and LUMO frontier orbital inter-
action for both polymorphs corroborates the strongest
positive overlap for the face-to-face p-stacking mode
observed in C 2/c polymorph of 2 (Figure 7c) resulting in an
apparently most complete interaction of the conjugated
phenylene moieties.[2,15,22] Subsequently, vacuum deposited
DOPT was studied as semiconductor for organic field-effect
transistors employing a bottom-gate/bottom-contact geome-
try (Figure 8a). It is expected that the full planar structure of 2
is a most favorable precondition for a good crystallinity of the
evaporated layer favoring in addition lateral p–p stacking at
the semiconductor/dielectric interface. Due to its face-to-face
structural motif found in the co-facial herringbone arrange-
ment, the C 2/c polymorph of DOPT 2 is a promising
candidate for OFET applications.[2]
Figure 8b shows the output and transfer curves that have
been obtained for OFET devices fabricated using a 40 nm
thick vacuum deposited DOPT layer. 16 OFET devices with
40, 20, 10 and 5 nm thick layers of 2 were evaluated,
respectively, for four different channel lengths of 20, 10, 5,
and 2.5 mm each (see Supporting Information). All output
curves of the devices with 40 and 20 nm DOPT thickness
exhibit a typical transistor like saturation behavior displaying
a small current hysteresis. For low drain voltages a slight S-
shape of the curve is evident for 40 nm DOPT layer pointing
to injection barriers between the gold contacts and the
organic semiconductor. This finding is in line with the results
from the DFT calculations (Figure 7a) which yield a HOMO
level of 5.08 eV. Assuming a work function of 5.1 eV for
gold[23] a small injection barrier of 0.02 eV results. Prototyp-
ical transistor behavior with a current saturation in the output
curves has been observed with only slight hysteresis with
a 20 nm functional DOPT layer. The observed drain current is
already about a factor of 10 smaller. Devices with 10 nm and
5 nm DOPT however, were not functional at all. This
corroborates with the detection of a non-uniform coverage
of the substrate as detected by AFM and does already become
noticeable with 20 nm DOPT as active layer (Figure 5).
Measurements with a drain voltage in the positive potential
range from 0 V to + 40 V did not show any n-type semi-
conducting behavior (see Supporting Information). Overview
of the detailed analysis of the determined hole mobilities mhole
and threshold voltages Vth of all functional devices are given
in Figure 8c as function of the channel length L. Both
quantities have been calculated from the transfer curves
using the Shockley equations[24] for the drain current. The
Figure 7. a) Predicted frontier orbitals HOMOÀ1, HOMO, LUMO and
LUMO+1 of DOPT 2 as obtained by DFT calculations (B3LYP/6-
31G**).[20] The respective HOMO/LUMO overlap in both polymorphs
of 2 is shown in (b) and (c).
imentally obtained bond length alternation derived from the
crystal structure determination (Figure 2a) fully agrees with
the size and sign of the calculated HOMO/LUMO set
based on the DFT method (Figure 7a). Furthermore, the
as calculated gaps between HOMOÀ1/HOMO (514 nm/
2.41 eV), HOMO/LUMO (563 nm/2.20 eV) (and LUMO/
LUMO+1 (595 nm/2.09 eV)) match well the recorded long-
wave p–p* transitions, respectively, of the corresponding UV/
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ing this, as longer channels increase the probability for
defects, for example, voids, in the conduction path. One
method to improve the crystal packing of a layer is its post
heat treatment. Therefore, the as prepared OFET with
a DOPT layer thickness of 40 nm have been additionally
heat treated under inert conditions on a hot plate at 1208C for
30 min. Indeed, mhole can be enhanced to some extent in this
way. Compared to so far reported optimized OFET devices
obtained from tetracene (vapor phase deposited:
0.005 cm2 VÀ1 sÀ1
;
resp.
solution
processed:
0.012–
0.067 cm2 VÀ1 sÀ1)[1a] or pentacene (vapor phase deposited:
0.014–0.40 cm2 VÀ1 sÀ1)[8n,u] as semiconductor layer, already
similar charge carrier mobilities of 0.01 cm2 VÀ1 sÀ1 could be
realized for the title compound DOPT herein without
optimizing the deposition parameters further.
In conclusion we have shown that the title compound 2
crystallizes in two molecular packing motifs depending on the
crystallization deposition mode. Two polymorphs of DOPT
crystallizing in space group P 21/n and C 2/c were observed
and a strong substrate induced growth mechanism favoring
the C 2/c phase in solution as well as on Si/SiO2 was
determined by GIXRD analysis. Based on theoretical con-
siderations a strong intermolecular p–p stacking with a sig-
nificant and stronger overlap contribution from the frontier
orbitals was found for the DOPT molecules in the C 2/c phase
as for the P 21/n polymorph. The intermolecular orientation
and overlap contribution of participating HOMO/LUMO
frontier orbitals in the C 2/c type gives strong evidence for an
enhanced charge carrier transport mechanism in vacuum
deposited DOPT. Gas phase deposition of 2 results in layers
composed of needle-like aggregates and explains the strong
dependence of the OFET performance characteristics from
the deposited film thickness. In the end our findings give
a profound explanation of the functional efficiency of the as
prepared OFET devices of the relatively unexplored acene
molecule 2.
Figure 8. a) Illustration of OFET device structure in bottom-gate/
bottom-contact geometry. A highly n-doped silicon gate (SiÀÀ) with
isolating top layer of SiO2 (90 nm) and deposited Au (30 nm) electro-
des was used as source and drain electrodes and 10 nm indium tin
oxide electrode adhesion layer. b) Output (left) and logarithmic trans-
fer curves (right) of transistor behavior with 40 nm layer of 2. The W/L
ratio is 1000, corresponding to a channel length L of 10 mm and
a width W of 10 mm. The on/off-ratio is up to 1.5”103 (for
VD =VG =À40 V). c) Average hole mobilities mhole (left) and threshold
voltages (right) as a function of channel length for various transistor
devices. The values illustrated with squares have been calculated for
the devices with 40 nm semiconductor, the triangles relate to values
from OFET devices with 20 nm thick functional layers of 2.
calculated hole mobility of DOPT is in the range of
10À3 cm2 VÀ1 sÀ1. However, apparent differences are observed
for the transistors with 40 nm or 20 nm DOPT layer. It is
evident that OFET devices with 40 nm DOPT layer exhibit
considerably higher mhole up to 0.01 cm2 VÀ1 sÀ1 (for L =
2.5 mm) compared to the OFET devices with 20 nm DOPT
which are up to 1.5 ” 10À3 cm2 VÀ1 sÀ1. The associated Vth of the
devices prepared with 40 nm DOPT are rather independent
on the channel length and lay around À13.4 V. This is
significantly higher compared to Vth of the devices with
20 nm DOPT which are around À20.0 V. As Vth is directly
related to the quality of the semiconductor/dielectric inter-
face, for example, the interface trap density, these results
indicate that the interface has a lower trap density in the case
of OFET with 40 nm compared to the one with 20 nm thick
DOPT layer. Although the DOPT molecules are well
behaved with respect to their internal crystalline order
(packing) of the molecules the crystallites are obviously not
densely enough packed to allow for an optimal charge carrier
transport along the transistor channel for a semiconductor
thickness of 20 nm. This hypothesis is strongly substantiated
by the AFM studies (Figure 5). The fact that mhole is found to
be maximum for the respective shortest channels is support-
CCDC 1448430 and 1448442 contain the supplementary
crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/
cif.
Acknowledgements
Discussions as well as initial OFET measurements where
done by S. Sanctis (TU Darmstadt) and are highly appreci-
ated. Support by Dr. W. Brçtz (GIXRD, TU Darmstadt) is
acknowledged.
Keywords: fullerene · fused-ring systems · hydrocarbons ·
organic field effect transistor · polycycles
How to cite: Angew. Chem. Int. Ed. 2016, 55, 6041–6046
Angew. Chem. 2016, 128, 6145–6150
[1] a) C.-T. Chien, C.-C. Lin, M. Watanabe, Y.-D. Lin, T.-H. Chao, T.
Chiang, X.-H. Huang, Y.-S. Wen, C.-H. Tu, C.-H. Sun et al., J.
Mater. Chem. 2012, 22, 13070 – 13075; b) Y. Xia, V. Kalihari,
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C. D. Frisbie, N. K. Oh, J. A. Rogers, Appl. Phys. Lett. 2007, 90,
162106 – 162108; c) R. Sarma, D. Saikia, Indian J. Pure Appl.
Phys. 2009, 47, 876 – 879; d) C. R. Newman, R. J. Chesterfield,
J. a. Merlo, C. D. Frisbie, Appl. Phys. Lett. 2004, 85, 422 – 425;
e) Y. Yoon, S. Kim, H. Lee, T. Kim, A. Babajanyan, K. Lee, B.
Friedman, Thin Solid Films 2011, 519, 5562 – 5566; f) H. M. Lee,
H. Moon, H.-S. Kim, Y. N. Kim, S.-M. Choi, S. Yoo, S. O. Cho,
Org. Electron. 2011, 12, 1446 – 1453; g) T. Hasegawa, J. Takeya,
Sci. Technol. Adv. Mater. 2009, 10, 024314; h) V. Podzorov, V. M.
Pudalov, M. E. Gershenson, Appl. Phys. Lett. 2003, 82, 1739 –
1741; i) V. Podzorov, S. E. Sysoev, E. Loginova, V. M. Pudalov,
M. E. Gershenson, Appl. Phys. Lett. 2003, 83, 3504 – 3506.
[2] H. Dong, X. Fu, J. Liu, Z. Wang, W. Hu, Adv. Mater. 2013, 25,
6158 – 6183.
[3] a) C. Dufraisse, R. Buret, C. R. Chim. 1932, 65, 962 – 964; b) C.
Dufraisse, R. Girard, Mem. Soc. Chim. 1934, 5, 1359 – 1367; c) C.
Moureu, C. Dufraisse, C. Mackall, Bull. Soc. Chim. Fr. 1923, 33,
934 – 942; d) C. Dufraisse, R. Horclois, Bull. Soc. Chim. Fr. 1936,
3, 1894 – 1905; e) M. Badoche, Ann. Chim. 1933, 20, 200; f) K. F.
Lang, E.-A. Theiling, Chem. Ber. 1956, 89, 2734 – 2737; g) G.
Wittig, H. Härle, E. Knauss, K. Niethammer, Chem. Ber. 1960,
951 – 962.
[4] Chaolumen, M. Murata, Y. Sugano, A. Wakamiya, Y. Murata,
Angew. Chem. Int. Ed. 2015, 54, 9308 – 9312; Angew. Chem.
2015, 127, 9440 – 9444.
[5] T. Wombacher, S. Foro, J. J. Schneider, Eur. J. Org. Chem. 2016,
569 – 578.
[6] G. Dai, J. Chang, W. Zhang, S. Bai, K.-W. Huang, J. Xu, C. Chi,
Chem. Commun. 2015, 51, 503 – 506.
[7] E. Clar in Polycyclic Hydrocarbons, Vol. I, Academic Press,
London, New York, Springer, Heidelberg, 1964.
2012, 134, 10349 – 10352; s) H. Xia, D. Liu, X. Xu, Q. Miao,
Chem. Commun. 2013, 49, 4301 – 4303; t) J. L. Jellison, C.-H.
Lee, X. Zhu, J. D. Wood, K. N. Plunkett, Angew. Chem. Int. Ed.
2012, 51, 12321 – 12324; Angew. Chem. 2012, 124, 12487 – 12490;
u) D. Knipp, R. A. Street, A. Vçlkel, J. Ho, J. Appl. Phys. 2003,
93, 347 – 355.
[9] a) J. J. Schneider, D. Spickermann, C. W. Lehmann, J. Magull,
H.-J. Krüger, J. Ensling, P. Gütlich, Chem. Eur. J. 2006, 12, 1427 –
1435; b) J. J. Schneider, D. Spickermann, T. Labahn, M. Fontani,
F. Laschi, P. Zanello, Chem. Eur. J. 2000, 6, 3686 – 3691; c) J. J.
Schneider, D. Wolf, C. W. Lehmann, Inorg. Chim. Acta 2003,
350, 625 – 632; d) C. Elschenbroich, R. Mockel, A. Vasil’kov, B.
Metz, K. Harms, Eur. J. Inorg. Chem. 1998, 10, 1391 – 1401;
e) J. J. Schneider, D. Spickermann, D. Bläser, R. Boese, P.
Rademacher, T. Labahn, J. Magull, C. Janiak, N. Seidel, K. Jacob,
Eur. J. Inorg. Chem. 2001, 1371 – 1382.
[10] a) A. V. Zabula, N. J. Sumner, A. S. Filatov, S. N. Spisak, V. M.
Grigoryants, M. A. Petrukhina, Eur. J. Inorg. Chem. 2012, 4675 –
4683; b) A. S. Filatov, N. J. Sumner, S. N. Spisak, A. V. Zabula,
A. Y. Rogachev, M. A. Petrukhina, Chem. Eur. J. 2012, 18,
15753 – 15760; c) A. V. Zabula, A. S. Filatov, S. N. Spisak, A. Y.
Rogachev, M. A. Petrukhina, Science 2011, 333, 1008 – 1011;
d) A. V. Zabula, S. N. Spisak, A. S. Filatov, M. A. Petrukhina,
Angew. Chem. Int. Ed. 2012, 51, 12194 – 12198; Angew. Chem.
2012, 124, 12360 – 12364; e) H. Bock, Nachr. Chem. 2001, 49, 18 –
21; f) C. Näther, H. Bock, Z. Havlas, T. Hauck, Organometallics
1998, 17, 4707 – 4715.
[11] a) E. Venuti, R. G. Della Valle, L. Farina, A. Brillante, M.
Masino, A. Girlando, Phys. Rev. B 2004, 70, 104106; b) M.
Brinkmann, S. Graff, C. Straupe, J. Wittmann, I. C. Sadron, C.
Chaumont, F. Nuesch, A. Aziz, M. Schaer, L. Zuppiroli, J. Phys.
Chem. B 2003, 107, 10531 – 10539.
[8] a) D. T. Chase, B. D. Rose, S. P. McClintock, L. N. Zakharov,
M. M. Haley, Angew. Chem. Int. Ed. 2011, 50, 1127 – 1130;
Angew. Chem. 2011, 123, 1159 – 1162; b) D. T. Chase, A. G. Fix,
B. D. Rose, C. D. Weber, S. Nobusue, C. E. Stockwell, L. N.
Zakharov, M. C. Lonergan, M. M. Haley, Angew. Chem. Int. Ed.
2011, 50, 11103 – 11106; Angew. Chem. 2011, 123, 11299 – 11302;
c) A. R. Mohebbi, F. Wudl, Chemistry 2011, 17, 2642 – 2646;
d) A. R. Mohebbi, J. Yuen, J. Fan, C. Munoz, M. F. Wang, R. S.
Shirazi, J. Seifter, F. Wudl, Adv. Mater. 2011, 23, 4644 – 4648;
e) X. Gu, X. Xu, H. Li, Z. Liu, Q. Miao, J. Am. Chem. Soc. 2015,
137, 16203 – 16208; f) H. Lee, Y. Zhang, L. Zhang, T. Mirabito,
E. K. Burnett, S. Trahan, A. R. Mohebbi, S. C. B. Mannsfeld, F.
Wudl, A. L. Briseno, J. Mater. Chem. C 2014, 2, 3361 – 3366; g) L.
Zhang, Y. Cao, N. S. Colella, Y. Liang, J.-L. BrØdas, K. N. Houk,
A. L. Briseno, Acc. Chem. Res. 2015, 48, 500 – 509; h) L. Zhang,
A. Fonari, Y. Liu, A. M. Hoyt, H. Lee, D. Granger, S. Parkin,
T. P. Russell, J. E. Anthony, J.-L. BrØdas et al., J. Am. Chem. Soc.
2014, 136, 9248 – 9251; i) X. Yang, D. Liu, Q. Miao, Angew.
Chem. Int. Ed. 2014, 53, 6786 – 6790; Angew. Chem. 2014, 126,
6904 – 6908; j) K. B. Burke, Y. Shu, P. Kemppinen, B. Singh, M.
Bown, I. I. Liaw, R. M. Williamson, L. Thomsen, P. Dastoor, W.
Belcher et al., Cryst. Growth Des. 2012, 12, 725 – 731; k) W. H.
Lee, D. H. Kim, Y. Jang, J. H. Cho, M. Hwang, Y. D. Park, Y. H.
Kim, J. I. Han, K. Cho, Appl. Phys. Lett. 2007, 90, 132106;
l) M. R. Rao, H. T. Black, D. F. Perepichka, Org. Lett. 2015, 17,
4224 – 4227; m) T. Kawase, J.-I. Nishida, Chem. Rec. 2015, 15,
1045 – 1059; n) R. Scholz, A.-D. Müller, F. Müller, I. Thurzo,
B. A. Paez, L. Mancera, D. R. T. Zahn, C. Pannemann, U.
Hilleringmann in Proc. SPIE 5940, Org. Field-Effect Transistors
IV (Eds.: Z. Bao, D. J. Gundlach), 2005, 59400I-1 – 59400I-7;
o) A. Bayn, X. Feng, K. Müllen, H. Haick, ACS Appl. Mater.
Interfaces 2013, 5, 3431 – 3440; p) M. Bendikov, F. Wudl, Chem.
Rev. 2004, 104, 4891 – 4946; q) Z. Sun, Q. Ye, C. Chi, J. Wu,
Chem. Soc. Rev. 2012, 41, 7857 – 7889; r) D. T. Chase, A. G. Fix,
S. J. Kang, B. D. Rose, C. D. Weber, Y. Zhong, L. N. Zakharov,
M. C. Lonergan, C. Nuckolls, M. M. Haley, J. Am. Chem. Soc.
[12] D. H. Arias, J. L. Ryerson, J. D. Cook, N. H. Damrauer, J. C.
Johnson, Chem. Sci. 2016, 41 – 44.
[13] S. Bergantin, M. Moret, Cryst. Growth Des. 2012, 12, 6035 – 6041.
[14] B. Scherwitzl, W. Lukesch, A. Hirzer, J. Albering, G. Leising, R.
Resel, A. Winkler, J. Phys. Chem. C 2013, 117, 4115 – 4123.
[15] a) V. Coropceanu, J. Cornil, A. Demetrio, S. Filho, Y. Olivier, R.
Silbey, J. Bre, Chem. Rev. 2007, 107, 926 – 952; b) C. R. Martinez,
B. L. Iverson, Chem. Sci. 2012, 3, 2191 – 2201.
[16] a) C. C. Mattheus, G. A. De Wijs, R. A. De Groot, T. T. M.
Palstra, J. Am. Chem. Soc. 2003, 125, 6323 – 6330; b) S. Schiefer,
M. Huth, A. Dobrinevski, B. Nickel, J. Am. Chem. Soc. 2007,
129, 10316 – 10317.
[17] a) S. Uttiya, L. Miozzo, E. M. Fumagalli, S. Bergantin, R. Ruffo,
M. Parravicini, A. Papagni, M. Moret, A. Sassella, J. Mater.
Chem. C 2014, 2, 4147 – 4155; b) L. Huang, Q. Liao, Q. Shi, H.
Fu, J. Ma, J. Yao, J. Mater. Chem. 2010, 20, 159 – 166.
[18] S. Venkatesan, E. C. Ngo, Q. Chen, A. Dubey, L. Mohammad, N.
Adhikari, A. F. Mitul, Q. Qiao, Nanoscale 2014, 6, 7093 – 7100.
[19] F. Würthner, T. E. Kaiser, C. R. Saha-Mçller, Angew. Chem. Int.
Ed. 2011, 50, 3376 – 3410; Angew. Chem. 2011, 123, 3436 – 3473.
[20] The three parameter hybrid nonlocal exchange functional of
Becke combined with the Lee–Yang–Parr gradient-corrected
correlation functional was used (B3LYP), a) A. Becke, J. Chem.
Phys. 1993, 98, 5648 – 5652; b) C. Lee, W. Yang, R. G. Parr, Phys.
Rev. B 1988, 37, 785 – 789.
[21] M. M. Ahmida, S. H. Eichhorn, ECS Trans. 2010, 25, 1 – 10.
[22] L. Wang, G. Nan, X. Yang, Q. Peng, Q. Li, Z. Shuai, Chem. Soc.
Rev. 2010, 39, 423 – 434.
[23] T. Yasuda, T. Goto, K. Fujita, T. Tsutsui, Appl. Phys. Lett. 2004,
85, 2098 – 2100.
[24] W. Shockley, W. T. Read, Phys. Rev. 1952, 87, 835 – 842.
Received: February 12, 2016
Revised: March 10, 2016
Published online: April 8, 2016
6046 www.angewandte.org
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Angew. Chem. Int. Ed. 2016, 55, 6041 –6046