Conjugated polymers of rylene diimide and phenothiazine for n-channel organic field-effect transistors

Article abstract of DOI:10.1021/ma3005058

A series of new n-type copolymers based on perylene diimide (PDI) or naphthalene diimide (NDI) and phenothiazine (PTZ) with different side chain length and molecular weight have been designed and synthesized by Pd-catalyzed Suzuki coupling polymerization with or without phase-transfer catalyst Aliquat 336. The effects of main chain, side chain, and molecular weight on the thermal, optical, electronic, and charge transport properties of the polymers have been investigated. Aliquat 336 improves molecular weight as well as reduces polydispersity index of the polymers. All the polymers exhibit a broad absorption extending from 300 to 900 nm. The main chain and side chain structure and molecular weight have minor effects on the HOMO (-5.8 to -5.9 eV) and LUMO (-3.7 to -3.8 eV) levels of the polymers. n-Channel field-effect transistors with bottom-gate top-contact geometry based on these copolymers exhibit electron mobilities as high as 0.05 cm² V^-1 s^-1 and on/off ratios as high as 10⁵ in nitrogen, which are among the best reported for rylene diimide-based polymers under the same test conditions.

Full text of DOI:10.1021/ma3005058

Article
pubs.acs.org/Macromolecules
Conjugated Polymers of Rylene Diimide and Phenothiazine for
n‑Channel Organic Field-Effect Transistors
Weiyi Zhou,†,§ Yugeng Wen,†,§ Lanchao Ma,†,§ Yunqi Liu,*,† and Xiaowei Zhan*,†
†Beijing National Laboratory for Molecular Sciences and CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese
Academy of Sciences, Beijing 100190, China
§Graduate University of Chinese Academy of Sciences, Beijing 100049, China
S
* Supporting Information
ABSTRACT: A series of new n-type copolymers based on
perylene diimide (PDI) or naphthalene diimide (NDI) and
phenothiazine (PTZ) with different side chain length and
molecular weight have been designed and synthesized by Pd-
catalyzed Suzuki coupling polymerization with or without phase-
transfer catalyst Aliquat 336. The effects of main chain, side chain,
and molecular weight on the thermal, optical, electronic, and
charge transport properties of the polymers have been
investigated. Aliquat 336 improves molecular weight as well as
reduces polydispersity index of the polymers. All the polymers
exhibit a broad absorption extending from 300 to 900 nm. The
main chain and side chain structure and molecular weight have
minor effects on the HOMO (−5.8 to −5.9 eV) and LUMO
(−3.7 to −3.8 eV) levels of the polymers. n-Channel field-effect transistors with bottom-gate top-contact geometry based on
these copolymers exhibit electron mobilities as high as 0.05 cm2 V−1 s−1 and on/off ratios as high as 105 in nitrogen, which are
among the best reported for rylene diimide-based polymers under the same test conditions.
tetracarboxylic diimide (NDI) are widely used building blocks
for n-type polymers. Since Zhan et al. reported the first rylene
diimide-based conjugated polymer in 2007,5a several n-type
conjugated polymers-based PDI and NDI have been synthe-
sized and used in n-channel OFETs and PSCs.5 A few ladder
polymers-based PDI and NDI were also reported.6
Owing to electron-rich nitrogen and sulfur heteroatoms in a
heterocyclic structure, phenothiazine (PTZ) has been well-
known as an excellent electron-donating chromophore.
Phenothiazine-based semiconductors are widely utilized in
organic electronic devices, such as light-emitting devices,7
photovoltaic cells,8 thin film transistors,9 and dye-sensitized
solar cells.10 Nonplanar butterfly conformation in phenothia-
zine can inhibit molecular aggregation and increase solubility of
the polymers.
The molecular weight as well as conjugation length of a
polymer semiconductor affects electronic and optical properties
as well as morphology of the polymer thin film. There have
been some reports addressing effect of molecular weight on
carrier mobility of conjugated polymers,11 suggesting that
increasing molecular weight could significantly improve charge
transporting ability of polymer semiconductors. However, most
of these literatures discussed effect of molecular weight in p-
INTRODUCTION
■
Polymer semiconductors have been the subject of intensive
academic and commercial interest over the past two decades.
Electronic devices based on polymer semiconductors, such as
polymer light-emitting diodes (PLEDs), polymer solar cells
(PSCs), and organic field-effect transistors (OFETs), have
advantages such as low cost, light weight, and flexibility.
Polymer semiconductors are generally classified as p-type, n-
type, and ambipolar materials according to the type of orderly
transferring charge carriers. Most of polymer semiconductors
are p-type that have seen a dramatic rise in performance over
the past decade, and hole mobilities on the order of 1 cm2 V−1
s−1 have been achieved in p-channel or ambipolar transistors.1
n-Type polymers are essential for the fabrication of organic p−
n junctions, PSCs, n-channel OFETs, PLEDs, and comple-
mentary logic circuits.2 Although some novel n-type conjugated
polymers have been created recently,2−6 development of this
field has lagged behind their p-type counterparts. Most of n-
type polymer semiconductors exhibited electron mobilities
below 0.1 cm2 V−1 s−1 in OFETs.
Rylene diimides are one of the classical n-type semiconductor
materials due to the substitution of rylene core with two sets of
π-accepting six-membered dicarboxylic imide rings that are
mutually conjugated. Rylene diimides exhibit relatively high
electron affinities, high electron mobilities, and excellent
thermal, chemical, and photochemical stabilities.4 Perylene-
3,4:9,10-tetracarboxylic diimide (PDI) and naphthalene-1,8:4,5-
Received: March 12, 2012
Revised: April 27, 2012
Published: May 8, 2012
© 2012 American Chemical Society
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type polymers, while a few literatures referred to that in n-type
polymers.
In this work, we designed and synthesized a series of n-type
conjugated copolymers of PDI or NDI and PTZ with different
side chains and different molecular weights (Figure 1). These
3,4:9,10-tetracarboxylic diimide (1) in 64% yield. The new
monomer, N,N′-bis(2-decyl-tetradecyl)-2,6-dibromonaphtha-
lene-1,4:5,8-tetracarboxylic diimide (2), was synthesized by
condensation of 2,6-dibromonaphthalene dianhydride with 2-
decyltetradecylamine in 13% yield. Suzuki coupling reactions
between N,N′-bis(2-decyl-tetradecyl)-1,7-dibromoperylene-
3,4:9,10-tetracarboxylic diimide,5a 1, or 2 and the known
compound 10-hexyl-2,8-bis(4,4,5,5-tetramethyl-1,3,2-dioxabor-
olan-2-yl)-phenothiazine (3)12 afforded new copolymers
PPP24-L, PPP16-L, and PNP24-L in 88%, 60%, and 73%
yields. Then other three copolymers PPP24-H, PPP16-H, and
PNP24-H with higher molecular weights were obtained by
Suzuki coupling reactions in the presence of phase-transfer
catalyst Aliquat 336.
All the polymers have good solubility in common organic
solvents such as chloroform, THF, and chlorobenzene.
Molecular weights of the polymers were determined by gel
permeation chromatography (GPC), using polystyrene stand-
ards as calibrants with THF as eluent (Table 1). The three
copolymers synthesized without Aliquat 336 (PPP24-L,
PPP16-L, and PNP24-L) exhibit number-average molecular
weights (Mn) below 7000 with polydispersity index (Mw/Mn)
up to 2.77, while the three copolymers synthesized with Aliquat
336 (PPP24-H, PPP16-H, and PNP24-H) exhibit relatively
larger Mn of 7800−11 800 with lower Mw/Mn below 1.7. Thus,
phase-transfer catalyst Aliquat 336 can improve degree of
polymerization and molecular weight as well as reduce
polydispersity index in Suzuki coupling polymerization.
The thermal properties of the polymers were determined by
thermogravimetric analysis (TGA) under nitrogen. The
decomposition temperatures (Td) at 5% weight loss for higher
molecular weight polymers PPP24-H, PPP16-H, and PNP24-
Figure 1. Chemical structures of copolymers discussed in this paper.
polymers exhibited electron mobilities as high as 0.05 cm2 V−1
s−1 in OFETs in nitrogen. We also investigated effect of main
chain, side chain, and molecular weight on electronic, optical,
and electron transport properties of the polymers.
RESULTS AND DISCUSSION
■
Synthesis and Characterization. The synthetic routes to
the polymers are outlined in Scheme 1. 1,7-Dibromoperylene
dianhydride was condensed with 2-hexyldecylamine to yield a
new compound N,N′-bis(2-hexyldecyl)-1,7-dibromoperylene-
Scheme 1. Synthesis of the Polymers
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Table 1. Molecular Weights and Thermal Properties of the
Polymers
Table 2. Absorption Maxima and Energy Levels of the
Polymers
a
a
a
b
a
b
c
d
d
e
polymer
yield (%)
Mn
Mw
Mw/Mn
Td (°C)
λmax,s
(nm)
λmax,f
(nm)
Eg
HOMO
(eV)
LUMO
(eV)
EgCV
polymer
(eV)
(eV)
PPP24-L
PPP24-H
PPP16-L
PPP16-H
PNP24-L
PNP24-H
88
54
60
57
73
76
4830
9971
2621
7850
6823
11821
9414
15278
3596
1.95
1.53
1.37
1.69
2.77
1.57
404
407
322
397
281
405
PPP24-L
330, 518, 336, 522,
600 610
1.5
−5.82
−5.85
−5.84
−5.81
−5.89
−5.83
−3.73
−3.75
−3.68
−3.74
−3.72
−3.79
2.1
PPP24-H
PPP16-L
PPP16-H
PNP24-L
328, 518, 332, 522,
610 630
1.5
1.4
1.5
1.4
1.4
2.1
2.1
2.1
2.2
2.0
13273
18966
18540
330, 522, 320, 526,
600 610
a
324, 518, 342, 524,
610 630
Number-average molecular weight (Mn), weight-average molecular
weight (Mw), and polydispersity index (Mw/Mn) determined by means
of GPC with THF as eluent on the basis of polystyrene calibration.
Decomposition temperature (5% weight loss) estimated using TGA
328, 362, 342, 364,
616 670
b
PNP24-H 328, 362, 342, 364,
628 682
under N2.
a
b
c
Absorption maxima in solution. Absorption maxima in film. Optical
d
band gap estimated from the absorption edge in film. HOMO and
LUMO estimated from the onset oxidation and reduction potentials,
respectively, assuming the absolute energy level of ferrocene/
ferrocenium to be 4.8 eV below vacuum. HOMO−LUMO gap
estimated electrochemistry.
H are 397−407 °C, while lower molecular weight polymers
PPP24-L, PPP16-L, and PNP24-L exhibit relatively lower Td
of 281−404 °C (Table 1).
e
Optical Properties. The UV−vis absorption spectra of all
polymers were measured in CHCl3 (ca. 10−6 M) solution and
in thin films (Figure 2). The detailed absorption data, including
maximum absorption wavelength of solutions and films and the
optical band gap deduced from the absorption edge in films, are
summarized in Table 2. Four PDI-based copolymers (PPP24-
L, PPP16-L, PPP24-H, and PPP16-H) in solution exhibit
similar absorption spectra with three absorption maxima, which
are reminiscent of those of PDI with dithienothiophene
(DTT)13 in the 1,7-positions and PDI−DTT copolymers.5c
These similarities suggest that the band at ca. 330 nm can be
assigned to a PTZ-centered transition, the 520 nm band to a
principally PDI-based transition, and the low-energy band
located at ca. 600 nm to a transition with significant PTZ-to-
PDI charge-transfer character. In absorption spectra of
solutions of two NDI-based copolymers (PNP24-L and
PNP24-H), there are also three characteristic bands located
at ca. 330, 360, and 620 nm, related to a PTZ-centered
transition, a principally NDI-based transition, and a significant
PTZ-to-NDI charge-transfer transition, respectively. The PTZ-
centered and PDI/NDI-based transition bands are not
susceptible to the polymer molecular weights, while the low-
energy charge-transfer bands of the copolymers with higher
molecular weights red-shift ca. 10 nm in comparison with those
with lower molecular weights. The N,N′-substituents on the
PDI have only minor effects on the spectra, as is also seen in
the case of small-molecule PDIs.14
The UV−vis spectra of thin films of all polymers show
absorption throughout the visible region. Moreover, there is
significant absorption extending into the near-IR region (as far
as ca. 900 nm, equivalent to optical band gaps as low as ca. 1.5
eV). The absorption spectra (particularly the low-energy
charge-transfer bands) of the polymer films show red-shift
relative to those of their chloroform solutions, which is a
common phenomenon for conjugated polymers owing to the
aggregation of the conjugated polymer main chains in the solid
films. The low-energy charge-transfer band of NDI-based
copolymers red-shifts 54 nm, larger than those for the PDI-
based copolymers (10−20 nm), indicating that there are
stronger intermolecular interactions in more planar NDI-based
copolymers.
Electrochemistry. To estimate the highest occupied
molecular orbital (HOMO) and the lowest unoccupied
molecular orbital (LUMO) energy levels of the conjugated
copolymers, we studied electrochemical properties using cyclic
voltammetry (CV) of films drop-cast onto glassy carbon
working electrodes. The cyclic voltammograms of all polymers
are shown in Figure 3. The HOMO and LUMO values of the
polymers are estimated from the onset oxidation and reduction
potentials, assuming the absolute energy level of FeCp2+/0 to be
4.8 eV below vacuum (Table 3). Six rylene-based copolymers
Figure 2. UV−vis spectra of the polymers in chloroform (left) and in film (right).
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LUMO levels of ca. −3.7 eV and HOMO levels of ca. −5.8 eV.
The energies of LUMO and HOMO for these polymers are
relatively insensitive to the main chain structure, side chain
structure, and molecular weight.
Field-Effect Transistors. Electron transport properties of
these polymers were investigated using OFET devices with a
bottom-gate top-contact configuration using Au as source and
drain electrodes. The output and transfer plots of all polymers
in nitrogen are shown in Figure 4 and Figure S1 (Supporting
Information), and the performance data of OFETs based on
the polymers are listed in Table 3.
The highest electron mobility obtained from the PDI-based
copolymers is up to 0.05 cm2 V−1 s−1 (PPP24-H), higher than
those of the PDI-DTT copolymer (0.013 cm2 V−1 s−1)5a and
the PDI-bithiophene copolymer (0.002 cm2 V−1 s−1)5e in the
same device geometry and in the same atmosphere. The highest
electron mobility obtained from the NDI-based copolymers is
up to 0.05 cm2 V−1 s−1 (PNP24-H), similar to that of the
NDI−bithiophene copolymer (0.06 cm2 V−1 s−1)5e in the same
device geometry and in the same atmosphere. However, the
same OFET arrays do not function in air since the LUMOs of
the polymers are not deep enough.
Figure 3. Cyclic voltammograms of polymer films in CH3CN/0.1 M
[nBu4N]+[PF6]− at 50 mV s−1. The horizontal scale refers to an
anodized Ag wire pseudoreference electrode.
Table 3. Performance of n-Channel OFETs Based on the
Polymers in Nitrogen
The copolymers with higher molecular weights show higher
electron mobilities than their lower molecular weight counter-
parts. Generally, electron transport in polymer films has two
pathways: transport along the main chain and interchain
hopping. Electron transport in conjugated polymers along an
individual chain is easier than transport through interchain
hopping.11a Since the carriers are frequently trapped in the
chain ends, increasing molecular weight means decreasing chain
end density, leading to improved carrier mobility.11e On the
other hand, increasing molecular weight improves the
coalescence between molecular chains and optimizes the film
polymer
μe (cm2 V−1 s−1
)
Ion/Ioff
VT (V)
PPP24-L
PPP24-H
PPP16-L
PPP16-H
PNP24-L
PNP24-H
0.02
0.05
10−4
0.02
0.02
0.05
104
105
104
105
105
104
21
8
9
17
4
14
exhibit an irreversible oxidation peak and one or two quasi-
reversible reduction waves. All of the copolymers exhibit similar
Figure 4. Current−voltage characteristics (Ids vs Vds) at several values of the gate voltage (Vg) (left) and Ids and (Ids)1/2 vs Vg plots (right) for a top
contact device based on PPP24-H (top) and PNP24-H (bottom).
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morphology in FET devices, finally enhancing interchain
hopping of carriers since the probability of this hopping is
related to the density of low activation energy pathways for
crossing between polymer chains whose number should
increase with the chain length.11a
Replacing the shorter 2-hexyldecyl groups in PPP16-L and
PPP16-H with longer 2-decyltetradecyl groups (PPP24-L and
PPP24-H) in the N-position of the PDI moiety leads to
significant enhancement in electron mobility, which could be
attributed to stronger intermolecular interaction and/or higher
molecular weight in the copolymers with longer side chains.
Figure 5 and Figure S2 show AFM height images of the
polymer films. All the polymer films exhibited typical
CONCLUSION
■
A series of new copolymers based on perylene diimide (PDI)
or naphthalene diimide (NDI) and phenothiazine (PTZ) with
different side chain length and molecular weight have been
synthesized by Pd-catalyzed Suzuki coupling polymerization
with or without phase-transfer catalyst Aliquat 336. Aliquat 336
improves molecular weight as well as reduces polydispersity
index of the polymers. The PDI-based polymers with longer
side chains have higher molecular weights than those with
shorter side chains. The polymers with higher molecular
weights exhibit relatively higher decomposition temperature,
red-shift of low-energy absorption band, more uniform film
morphology, stronger π−π stacking, and higher electron
mobility than those with lower molecular weights. The main
chain and side chain structure and molecular weight have minor
effects on the HOMO and LUMO levels of the polymers. The
electron mobilities obtained from the PDI or NDI-based
copolymers are as high as 0.05 cm2 V−1 s−1, which are among
the best reported for rylene diimide-based polymers under the
same test conditions.
EXPERIMENTAL SECTION
■
Materials. Unless stated otherwise, starting materials were
obtained from Aldrich or Acros and were used without further
purification. 1,7-Dibromoperylene dianhydride,15 2,6-dibromonaph-
thalene-1,4:5,8-tetracarboxydianhydride,16 2-decyltetradecylamine,5a 2-
hexyldecylamine,5a 10-hexyl-2,8-bis(4,4,5,5-tetramethyl-1,3,2-dioxabor-
olan-2-yl)-phenothiazine,12 and N,N′-bis(2-decyl-tetradecyl)-1,7-dibro-
moperylene-3,4:9,10-tetracarboxylic diimide5a were synthesized ac-
cording to the literature methods.
Figure 5. AFM topographic images (5 μm × 5 μm) of thin films of
PPP24-H and PPP24-L.
amorphous state without any crystalline domains. The root-
mean-square (rms) roughness of these films is in the range of
0.3−0.9 nm. More uniform morphology with lower defect
density was observed for the polymers with higher molecular
weight relative to those with lower molecular weight, which is
beneficial to electron transport.
In order to further investigate the thin film organization of
the copolymers, we carried out X-ray diffraction measurements
as shown in Figures 6 and Figure S3. All thin films of the
1
Characterization. The H and 13C NMR spectra were measured
on a Bruker AVANCE 400 MHz spectrometer using tetramethylsilane
(TMS; δ = 0 ppm) as an internal standard. Mass spectra were
measured on a Bruker Daltonics BIFLEX III MALDI-TOF analyzer
using MALDI mode. Elemental analyses were carried out using a
FLASH EA1112 elemental analyzer. Solution (chloroform) and thin-
film (on quartz substrate) UV−vis absorption spectra were recorded
on a JASCO V-570 spectrophotometer. Electrochemical measure-
ments were carried out under nitrogen on a deoxygenated solution of
tetra-n-butylammonium hexafluorophosphate (0.1 M) in acetonitrile
using a computer-controlled Zahner IM6e electrochemical work-
station, a glassy-carbon working electrode coated with polymer films, a
platinum-wire auxiliary electrode, and an Ag wire anodized with AgCl
as a pseudoreference electrode. Thermogravimetric analysis (TGA)
measurements were performed on Shimadzu thermogravimetric
analyzer (model DTG-60) under a nitrogen flow at a heating rate of
10 °C min−1. The gel permeation chromatography (GPC) measure-
ments were performed on a Waters 515 chromatograph connected to a
Waters 2410 refractive index detector, using THF as eluent and
polystyrene standards as calibrants; three Waters Styragel columns
(HT3, 5, 6E) connected in series were used. The X-ray diffraction
(XRD) pattern was recorded by a Rigaku D/max-2500 diffractometer
operated at 40 kV voltage and a 200 mA current with Cu Kα radiation.
The samples for XRD measurements were prepared by spin-coating
chloroform solution of the polymers on the OTS-modified SiO2.
Fabrication and Characterization of Field-Effect Transistors.
FET devices were fabricated with a top-contact bottom-gate
configuration. A heavily doped n-type Si wafer with a SiO2 layer of
500 nm and a capacitance of 11.5 nF cm−2 was used as the gate.
Octadecyltrichlorosilane (OTS) was used as a self-assembled surface
modifier for SiO2. A 60 nm thick ( 10 nm) semiconductor film was
spin-coated on top of the OTS-treated SiO2 from 10 mg mL−1
chloroform solution of the polymers. Gold source and drain contacts
(40 nm) were deposited on the organic layer through a shadow mask
under high vacuum. The channel length (L) and width (W) were 80
μm and 8.8 mm, respectively. All the measurement of electric property
was carried out in nitrogen using a Keithley 4200 SCS semiconductor
Figure 6. X-ray diffraction patterns of thin films of PPP24-H and
PPP24-L.
polymers with higher molecular weights exhibit a broad peak in
2θ = 15°−25° region accompanied by one sharp peak at 21.4°
corresponding to π−π stacking distance of 0.41 nm. Thin films
of polymers PPP24 and PNP24 with lower molecular weights
do not exhibit a broad peak in 2θ = 15°−25° region. Thus, high
molecular weight is beneficial to π−π stacking of the polymer
chain and electron transport.
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parameter analyzer. The mobility in the saturated regime was extracted
from the following equation: Ids = Ciμe(W/2L)(Vg − VT)2, where Ids is
the drain current, Ci is the capacitance per unit area of the gate
dielectric layer, μe is field-effect electron mobility, W and L are the
channel width and length, and Vg and VT are the gate voltage and
threshold voltage, respectively. AFM images of organic thin films were
obtained on a NanoMan VS microscope (Digital Instruments) in
tapping mode.
MHz, CDCl3): δ 8.5 (br, 2H), 8.3 (br, 4H), 7.8 (br, 2H), 7.6 (br, 4H),
4.1−3.9 (br, 6H), 2.00 (br, 4H), 1.6−1.0 (br, 86H), 0.9−0.6 (br,
15H). Anal. Calcd for (C90H123N3O4S)n: C, 80.49; H, 9.23; N, 3.13.
Found: C, 76.04; H, 8.86; N, 2.82.
Poly{[N,N′-bis(2-hexyldecyl)-3,4:9,10-perylenediimide-1,7-
diyl]-alt-(10-hexyl- phenothiazine-2,8-diyl)}. To a 50 mL three-
neck round-bottom flask were added N,N′-bis(2-hexyldecyl)-1,7-
dibromo-3,4:9,10-perylene diimide (0.51 mmol, 505 mg) and 10-
hexyl-2,8-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenothia-
zine (0.51 mmol, 271 mg), and the mixture was deoxygenated with
nitrogen for 30 min. Pd(PPh3)4 (59 μmol, 68 mg), toluene (15 mL),
and a solution of K2CO3 (0.57 g) in deoxygenated water (5 mL) were
added under nitrogen. The dark red solution was stirred at 95 °C for 3
days. Phenylboronic acid (87 μmol, 10.6 mg) was added under
nitrogen. The brown sticky mixture was stirred at 95 °C for 5 h.
Bromobenzene (0.3 mL) was added under nitrogen. The mixture was
stirred at 95 °C for 10 h. The brown sticky mixture was cooled down
to room temperature. The mixture was extracted with CH2Cl2 (2 ×
100 mL), washed with water (2 × 100 mL), and dried over anhydrous
MgSO4. The solution was concentrated to 15 mL and then dropped
into 100 mL of methanol. The black precipitate was filtered and
washed with methanol. Finally, the polymer was purified by size
exclusion column chromatography over Bio-Rad Bio-Beads S-X1
eluting with chloroform to afford a dark red-brown solid. PPP16-L:
340 mg, 60%. GPC: Mn, 2621; Mw, 3596; Mw/Mn, 1.37. 1H NMR (400
MHz, CDCl3): δ 8.6 (br, 2H), 8.3 (br, 4H), 7.7 (br, 2H), 7.5 (br, 4H),
4.1−3.9 (br, 6H), 2.00 (br, 4H), 1.6−1.0 (br, 54H), 0.9−0.7 (br,
15H). Anal. Calcd for (C74H91N3O4S)n: C, 79.46; H, 8.20; N, 3.76.
Found: C, 70.59; H, 8.43; N, 2.75. PPP16-H: with Aliquat 336 (190
μmol, 76 mg) in the reaction mixture, 320 mg, 57%. GPC: Mn, 7850;
Synthesis. N,N′-Bis(2-hexyldecyl)-1,7-dibromo-3,4:9,10-per-
ylene Diimide (1). 1,7-Dibromoperylene-3,4:9,10-tetracarboxylic acid
dianhydride (2.96 mmol, 1.63 g) in 120 mL of nBuOH/H2O (1:1, v/v)
was sonicated for 10 min. 2-Hexyldecylamine (11.33 mmol, 2.73 g)
was added, and the reaction mixture was stirred at 80 °C for 24 h
under nitrogen. Concentrated aqueous HCl (13 mL) was added, and
the mixture was stirred at room temperature for 30 min. The mixture
was extracted with chloroform (2 × 90 mL), washed with water (2 ×
180 mL), and dried over anhydrous MgSO4. The solvent was removed
and the residue was purified by column chromatography over silica gel
eluting with CH2Cl2/petroleum ether (1:1) to give a red solid (1.90 g,
1
64%). H NMR (400 MHz, CDCl3): δ 9.36 (d, J = 8.1 Hz, 2H), 8.81
(s, 2H), 8.59 (d, J = 8.2 Hz, 2H), 4.12 (d, J = 7.1 Hz, 4H), 1.98 (m,
2H), 1.5−1.1 (m, 48H), 0.85 (m, 12H). 13C NMR (100 MHz,
CDCl3): δ 163.0, 162.5, 138.0, 132.9, 132.6, 129.8, 129.0, 128.3, 126.8,
123.0, 122.6, 120.8, 44.8, 36.6, 32.0, 31.8, 31.6, 30.0, 29.7, 29.6, 29.3,
26.5, 22.6, 14.1. MS (MALDI): m/z 996 (M+). Anal. Calcd for
C56H72Br2N2O4: C, 67.46; H, 7.28; N, 2.81. Found: C, 67.53; H, 7.25;
N, 2.91.
N,N′-Bis(2-decyltetradecyl)-2,6-dibromo-1,4:5,8-naphtha-
lene Diimide (2). A mixture of 2,6-dibromonaphthalene-1,4:5,8-
tetracarboxylic acid dianhydride (1.85 mmol, 789 mg), 2-decylte-
tradecylamine (5.08 mmol, 1.80 g), o-xylene (5 mL), and propionic
acid (3 mL) was stirred overnight at 140 °C. Upon cooling to room
temperature, the mixture was extracted with chloroform (2 × 90 mL),
washed with water (2 × 180 mL), and dried over anhydrous MgSO4.
The residue was purified by column chromatography on silica gel with
a mixture of chloroform:petroleum ether (1:1, v/v) as eluent, affording
1
Mw, 13273; Mw/Mn, 1.69. H NMR (400 MHz, CDCl3): δ 8.5 (br,
2H), 8.3 (br, 4H), 7.8 (br, 2H), 7.6 (br, 4H), 4.1−3.9 (br, 6H), 2.00
(br, 4H), 1.6−1.0 (br, 54H), 0.9−0.6 (br, 15H). Anal. Calcd for
(C74H91N3O4S)n: C, 79.46; H, 8.20; N, 3.76. Found: C, 70.71; H, 7.90;
N, 3.09.
1
a pale yellow solid (271 mg, 13.4%). H NMR (400 MHz, CDCl3): δ
8.99 (s, 2H), 4.14 (d, J = 7.3 Hz, 4H), 1.98 (m, 2H), 1.20−1.40 (m,
80H), 0.84−0.89 (m, 12H). 13C NMR (100 MHz, CDCl3): δ 161.3,
161.1, 139.3, 128.5, 127.9, 125.4, 124.2, 45.6, 36.6, 32.1, 32.0, 31.7,
30.2, 29.8, 29.7, 29.5, 26.5, 22.8, 14.3. MS (MALDI): m/z 1095 (M+).
Anal. Calcd for C62H100Br2N2O4: C, 67.86; H, 9.19; N, 2.55. Found: C,
67.73; H, 9.04; N, 2.59.
Poly{[N,N′-bis(2-decyltetradecyl)-1,4:5,8-naphthalenedii-
mide-2,6-diyl]-alt-(10-hexylphenothiazine-2,8-diyl)}. To a 25
mL three-neck round-bottom flask were added N,N′-bis(2-decylte-
tradecyl)-2,6-dibromo-1,4:5,8-naphthalene diimide (0.15 mmol, 166
mg) and 10-hexyl-2,8-bis(4,4,5,5-tetramethyl-1,3,2- dioxaborolan-2-
yl)-phenothiazine (0.15 mmol, 81 mg), and the mixture was
deoxygenated with nitrogen for 30 min. Pd(PPh3)4 (31 μmol, 36
mg), toluene (4 mL), and a solution of K2CO3 (131 mg) in
deoxygenated water (0.5 mL) were added under nitrogen. The yellow
solution was stirred at 95 °C for 3 days. Phenylboronic acid (8.1 mg)
was added under nitrogen. The dark green mixture was stirred at 95
°C for 5 h. Bromobenzene (0.1 mL) was added under nitrogen. The
dark green mixture was stirred at 95 °C for 10 h. The dark green
mixture was cooled down to room temperature. The mixture was
extracted with CH2Cl2 (2 × 100 mL), washed with water (2 × 100
mL), and dried over anhydrous MgSO4. The solution was
concentrated to 15 mL and then dropped into 100 mL of methanol.
The dark green precipitate was filtered and washed with methanol.
The dark green precipitate was filtered and purified by size exclusion
column chromatography over Bio-Rad Bio-Beads S-X1 eluting with
chloroform to afford a dark green solid. PNP24-L: 134 mg, 73%. GPC:
Mn, 6823; Mw, 18 966; Mw/Mn, 2.77. 1H NMR (400 MHz, CDCl3): δ
8.6 (br, 2H), 7.2 (br, 2H), 7.0 (br, 4H), 4.2−4.0 (br, 6H), 2.00 (br,
4H), 1.6−1.1 (br, 86H), 0.9−0.7 (br, 15H). Anal. Calcd for
(C80H119N3O4S)n: C, 78.83; H, 9.84; N, 3.45. Found: C, 72.89; H,
8.74; N, 2.95. PNP24-H: with Aliquat 336 (108 μmol, 44 mg) in the
reaction mixture, 140 mg, 76%. GPC: Mn, 11821; Mw, 18 540; Mw/Mn,
Poly{[N,N′-bis(2-decyltetradecyl)-3,4:9,10-perylenediimide-
1,7-diyl]-alt-(10-hexyl-phenothiazine-2,8-diyl)}. To a 50 mL
three-neck round-bottom flask were added N,N′-bis(2-decyltetradec-
yl)-1,7-dibromo-3,4:9,10-perylene diimide (0.25 mmol, 308 mg) and
10-hexyl-2,8-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-pheno-
thiazine (0.25 mmol, 135 mg), and the mixture was deoxygenated with
nitrogen for 30 min. Pd(PPh3)4 (18 μmol, 21 mg), toluene (15 mL),
and an aqueous solution of K2CO3 (1.36 g) in deoxygenated water (25
mL) were added under nitrogen. The dark red solution was stirred at
95 °C for 3 days. Phenylboronic acid (46 μmol, 5.6 mg) was added
under nitrogen. The brown sticky mixture was stirred at 95 °C for 5 h.
Bromobenzene (1.8 mmol, 290 mg) was added under nitrogen. The
brown sticky mixture was stirred at 95 °C for 10 h. The brown sticky
mixture was cooled down to room temperature. The mixture was
extracted with CH2Cl2 (2 × 100 mL), washed with water (2 × 100
mL), and dried over anhydrous MgSO4. The solution was
concentrated to 15 mL and then dropped into 200 mL of methanol.
The brown precipitate was filtered and washed with methanol. Finally,
the polymer was purified by size exclusion column chromatography
over Bio-Rad Bio-Beads S-X1 eluting with chloroform to afford a dark
red-brown solid. PPP24-L: 300 mg, 88%. GPC: Mn, 4830; Mw, 9414;
1
Mw/Mn, 1.95. H NMR (400 MHz, CDCl3): δ 8.6 (br, 2H), 8.3 (br,
4H), 7.8 (br, 2H), 7.5 (br, 4H), 4.1−3.9 (br, 6H), 2.00 (br, 4H), 1.6−
1.0 (br, 86H), 0.9−0.6 (br, 15H). Anal. Calcd for (C90H123N3O4S)n:
C, 80.49; H, 9.23; N, 3.13. Found: C, 74.70; H, 8.82; N, 2.83. PPP24-
H: with Aliquat 336 (37 μmol, 15 mg) in the reaction mixture, 181
1
1.57. H NMR (400 MHz, CDCl3): δ 8.6 (br, 2H), 7.2 (br, 2H), 7.0
(br, 4H), 4.1−3.9 (br, 6H), 2.00 (br, 4H), 1.6−1.0 (br, 86H), 0.9−0.7
(br, 15H). Anal. Calcd for (C80H119N3O4S)n: C, 78.83; H, 9.84; N,
3.45. Found: C, 71.84; H, 9.42; N, 3.01.
1
mg, 54%. GPC: Mn, 9971; Mw, 15278; Mw/Mn, 1.53. H NMR (400
4120
dx.doi.org/10.1021/ma3005058 | Macromolecules 2012, 45, 4115−4121

Macromolecules
Article
C. H.; Hashimoto, K. J. Mater. Chem. 2010, 20, 2362. (k) Zhou, E.;
Cong, J.; Wei, Q.; Tajima, K.; Yang, C. H.; Hashimoto, K. Angew.
Chem., Int. Ed. 2011, 50, 2799. (l) Popere, B. C.; Della Pelle, A. M.;
Thayumanavan, S. Macromolecules 2011, 44, 4767. (m) Sajoto, T.;
Tiwari, S. P.; Li, H.; Risko, C.; Barlow, S.; Zhang, Q.; Cho, J. Y.;
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(b) Durban, M. M.; Kazarinoff, P. D.; Segawa, Y.; Luscombe, C. K.
Macromolecules 2011, 44, 4721. (c) Yuan, Z.; Xiao, Y.; Yang, Y.; Xiong,
T. Macromolecules 2011, 44, 1788.
ASSOCIATED CONTENT
* Supporting Information
Output and transfer curves of OFETs; AFM images of PPP16-
H, PPP16-L, PNP24-H, and PNP24-L; XRD patterns of
PPP16-H, PPP16-L, PNP24-H, and PNP24-L. This material is
available free of charge via the Internet at http://pubs.acs.org.
■
S
AUTHOR INFORMATION
Corresponding Author
*E-mail: xwzhan@iccas.ac.cn (X.Z.); liuyq@iccas.ac.cn (Y.L.).
Notes
■
(7) (a) Jang, S. E.; Lee, J. Y. J. Ind. Eng. Chem. 2011, 17, 575.
(b) Hsieh, B. Y.; Chen, Y. J. Polym. Sci., Part A: Polym. Chem 2009, 47,
833. (c) Kong, X. X.; Kulkarni, A. P.; Jenekhe, S. A. Macromolecules
2003, 36, 8992.
The authors declare no competing financial interest.
(8) (a) Mi, D.; Kim, J.-H.; Xu, F.; Lee, S.-H.; Yoon, S. C.; Shin, W. S.;
Moon, S. J.; Lee, C.; Hwang, D. H. Sol. Energy Mater. Sol. Cells 2011,
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Shin, W. S.; Moon, S. J.; Hwang, D. H.; Kang, I. N. J. Polym. Sci., Part
A: Polym. Chem. 2010, 48, 635. (c) Huang, J. H.; Li, K. C.; Wei, H. Y.;
Chen, P. Y.; Lin, L. Y.; Kekuda, D.; Lin, H. C.; Ho, K. C.; Chu, C. W.
Org. Electron. 2009, 10, 1109.
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ACKNOWLEDGMENTS
■
This material is based upon work supported in part by the
NSFC (Grants 21025418, 50873107, and 21021091), 973
Project (Grant 2011CB808401), the Chinese Academy of
Sciences, and Solvay S. A.
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