Angular-shaped 4,9-dialkylnaphthodithiophene-based donor-acceptor copolymers for efficient polymer solar cells and high-mobility field-effect transistors

Article abstract of DOI:10.1021/acs.macromol.5b00098

Although the tetracyclic angular-shaped naphthodithiophenes (aNDTs) derivatives are an emergent building block for constructing promising semiconductor conjugated polymers, the absence of aliphatic side chains as solubilizing groups on the aNDTs greatly restricted their further application toward polymer synthesis. To create a new class of aNDT-based polymers for widespread applications in solution-processable OFETs and PSCs, side-chain engineering of the aNDT-based structures plays a pivotal role in improving solubility and optimizing electronic/steric properties associated with the resultant solar cell characteristics. In this research, we developed an efficient and straightforward methodology to construct the angular naphthodithophene core with regiospecific introduction of two aliphatic chains at its 4,9-positions via a base-induced double 6π-cyclization. For the first time, the corresponding 2,7-distannylated-4,9-dialkylated aNDT monomers were polymerized with FBT and DPP acceptors to make two new PaNDTDTFBT and PaNDTDPP donor-acceptor copolymers. The photovoltaic devices based on the PaNDTDTFBT:PC₇₁BM blend not only showed a promising PCE of 6.52% with conventional configuration but also achieved a higher PCE of 6.86% with inverted configuration. Moreover, PaNDTDPP with strong intermolecular interaction achieved a high FET hole mobility of 0.202 cm² V^-1 s^-1.

Full text of DOI:10.1021/acs.macromol.5b00098

Article
pubs.acs.org/Macromolecules
Angular-Shaped 4,9-Dialkylnaphthodithiophene-Based Donor−
Acceptor Copolymers for Efficient Polymer Solar Cells and High-
Mobility Field-Effect Transistors
Sheng-Wen Cheng, Che-En Tsai, Wei-Wei Liang, Yung-Lung Chen, Fong-Yi Cao, Chain-Shu Hsu,
and Yen-Ju Cheng*
Department of Applied Chemistry, National Chiao Tung University, 1001 University Road, Hsin-Chu 30010, Taiwan
*
S Supporting Information
ABSTRACT: Although the tetracyclic angular-shaped naphthodithiophenes
aNDTs) derivatives are an emergent building block for constructing promising
(
semiconductor conjugated polymers, the absence of aliphatic side chains as
solubilizing groups on the aNDTs greatly restricted their further application
toward polymer synthesis. To create a new class of aNDT-based polymers for
widespread applications in solution-processable OFETs and PSCs, side-chain
engineering of the aNDT-based structures plays a pivotal role in improving
solubility and optimizing electronic/steric properties associated with the
resultant solar cell characteristics. In this research, we developed an efficient and
straightforward methodology to construct the angular naphthodithophene core
with regiospecific introduction of two aliphatic chains at its 4,9-positions via a
base-induced double 6π-cyclization. For the first time, the corresponding 2,7-
distannylated-4,9-dialkylated aNDT monomers were polymerized with FBT
and DPP acceptors to make two new PaNDTDTFBT and PaNDTDPP
donor−acceptor copolymers. The photovoltaic devices based on the PaNDTDTFBT:PC BM blend not only showed a
71
promising PCE of 6.52% with conventional configuration but also achieved a higher PCE of 6.86% with inverted configuration.
Moreover, PaNDTDPP with strong intermolecular interaction achieved a high FET hole mobility of 0.202 cm V s .
2
−1 −1
INTRODUCTION
Takimiya and Osaka first introduced two alkyl groups at the
■
outer positions (5,10-positions) of the central naphthalene
Donor−acceptor (D−A) copolymers have been extensively
utilized in organic photovoltaics (OPVs) and organic field-
effect transistors (OFETs) due to their easy tunability of
molecular properties and excellent solution processability. A
variety of novel electron-rich conjugated building blocks have
thus been developed for polymerization. Compared to the
tricyclic benzodithiophene derivatives representing the most
successful component for constructing high-performance D−A
copolymers of OPVs, the tetracyclic naphthodithiophenes
7
moiety in the aNDT. Compared to the polymer incorporating
8
the unsubstituted aNDT units, the 5,10-dialkyl aNDT-based
copolymer showed a better solubility and orientational order,
leading to an impressive power conversion efficiency (PCE)
9
1
over 8%. Li et al. reported a 4,9-dialkoxy aNDT-based D−A
10
copolymer delivering moderate solar cell performances. It is
thus desirable to further create another isomeric structure, 4,9-
dialkyl-aNDT, to investigate the substituent effects on the
electronic and structural properties of the resulting copolymers.
In this regard, we have developed a useful methodology to
regiospecifically implant two alkyl chains at the inner 4,9-
2
(
NDTs) also attract growing attention considering their
3
extended conjugation as well as diverse structures. Depending
on the molecular geometry, the NDT derivatives can have
linear-shaped (lNDT) and angular-shaped (aNDT) isomeric
structures (Figure 1). It was found that aNDT-based
copolymers have higher ordered structures than the lNDT4-
based copolymers, thereby achieving higher OFET mobilities.
Furthermore, the aNDT molecules exhibit lower-lying HOMO
energy levels than the lNDT counterparts, which are beneficial
for better air stability and greater open-circuit voltage (V ) for
OPVs. To fully exploit the aNDT-containing polymers for the
optoelectronic applications, side-chain engineering by introduc-
ing solubilizing groups onto an aNDT framework is highly
essential to not only ensure the solution processability but also
11
positions of an aNDT unit. By using this synthetic strategy,
two 4,9-di(2-octyldodecyl) aNDT (aNDT-OD) and 4,9-di(2-
butyloctyl) aNDT (aNDT-BO) units were successfully
synthesized. The two corresponding distannylated aNDT
(
Sn-aNDT) monomers were copolymerized with 4,7-bis(5-
5
bromo-4-octylthiophen-2-yl)-5,6-difluorobenzo[1,2,5]-
12
thiadiazole (DTFBT) and 3,6-bis(5-bromothiophen-2-yl)-
,5-bis(2-ethylhexyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-
oc
2
Received: January 16, 2015
Revised: March 10, 2015
6
induce suitable molecular packing. To address the issue,
©
XXXX American Chemical Society
A
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Figure 1. Chemical structures of aNDTs, 4,9-dialkyl aNDT, and their corresponding copolymers, PaNDTDTFBT and PaNDTDPP.
Scheme 1. Synthetic Routes for the 4,9-Dialkyl aNDT Units and the Corresponding Copolymers
1
3
dione (DPP) acceptors to prepare two PaNDTDTFBT and
PaNDTDPP copolymers, respectively (Figure 1). Their
molecular properties have been carefully characterized, and
bulk-heterojunction (BHJ) solar cells incorporating the
polymers have exhibited promising photovoltaic performance
in both conventional and inverted architectures.
alkyl substituents regiospecifically at the 4,9-positions of the
aNDT unit. The length and the branch of alkyl groups can be
adjustable depending on the preparation of the alkynes. The
lithiation of aNDT-OD and aNDT-BO followed by reacting
with trimethyltin chloride, resulted in the Sn-aNDT-OD and
Sn-aNDT-BO monomers, respectively. Two monomers were
copolymerized with 4 and 5 monomers by the Stille coupling to
give PaNDTDTFBT and PaNDTDPP, respectively (Scheme
RESULTS AND DISCUSSION
■
1
). The molecular weight of PaNDTDTFBT (M = 67.8 kDa;
n
Synthesis. The synthesis of the monomers Sn-aNDT is
described in Scheme 1. 1,2-Bis(3-bromothiophen-2-yl)ethene
2) with exclusive E-form olefinic configuration was synthesized
PDI = 1.2) and PaNDTDPP (M = 23.1 kDa; PDI = 3.1) was
n
determined by GPC measurements in THF.
(
Thermal Properties. The thermal stability of two polymers
was measured by thermogravimetric analysis (TGA).
PaNDTDTFBT and PaNDTDPP showed sufficiently high
by the McMurry coupling reaction of 3-bromothiophene-2-
carbaldehyde (1) in the presence of titanium tetrachloride and
a reducing agent of Zn. The Sonogashira coupling of (E)-1,2-
bis(3-(alkynyl)thiophen-2-yl)ethene with 4-butyldec-1-yne or
-octyltetradec-1-yne afforded the dithiophenyl-ene-diynes 3a
and 3b in high yields, respectively. The double base-induced
π-cyclizations of compound 3 with diazabicycloundecene
DBU) constructed the central naphthalene moiety with the
decomposition temperatures (T ) of 447 and 429 °C,
d
4
respectively (Figure 2). According to the differential scanning
calorimetry (DSC) analysis, PaNDTDPP does not show
6
(
obvious melting point (T ) while PaNDTDTFBT exhibits
m
crystalline nature with the observation of a T at 300 °C during
m
B
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suggest that the electron-withdrawing ability of the DPP is
stronger than that of the FBT unit.
Electrochemical Properties. Cyclic voltammetry (CV)
was used to examine the electrochemical properties and
evaluate the HOMO/LUMO levels and the electronic band
gaps of the polymers (Table 1 and Figure 6). The two polymers
showed stable and reversible processes in the oxidative scans,
which are important prerequisites for p-type organic semi-
conductors. The deep-lying HOMO energy levels were
estimated to be −5.47 eV for PaNDTDTFBT and −5.34 eV
for PaNDTDPP. It is worth noting that compared to the alkoxy
substituents, the less donating alkyl groups at the 4,9-positions
of the aNDT could lower the HOMO levels of the aNDT-
10b,14
based copolymers.
On the other hand, the LUMO energy
levels are approximately located at −3.50 eV for
PaNDTDTFBT and −3.64 eV for PaNDTDPP, which are
higher than the LUMO level of the PC BM (−3.8 eV) to
Figure 2. Thermogravimetric analysis of PaNDTDTFBT and
PaNDTDPP.
7
1
ensure energetically favorable electron transfer.
Theoretical Calculations. To further understand the
molecular orbital properties of the polymeric π-electron
systems, quantum-chemical calculations were performed with
heating and a crystallization point (T ) at 280 °C upon cooling
c
(
Figure 3).
X-ray Diffraction. Two-dimensional wide-angle X-ray
15
the Gaussian09 suite employing the B3LYP density functional
diffraction (2D-WAXD) was employed to investigate the
crystallinity of two polymers which were extruded as a fiber
at 250 °C in the solid state. The results are shown in Figure 4.
Diffraction arcs were distinctly observed in PaNDTDTFBT
in combination with the 6-31G(d) basis set. Geometry
optimizations were performed with solvation in dichloro-
methane by applying the polarized continuum model (PCM)
and with tight SCF and convergence criteria and an ultrafine
integration grid by applying the GEDIIS optimization
algorithm. The minimum nature of each stationary point was
confirmed by a frequency analysis. For simplicity, two model
compounds, aNDTDTFBT and aNDTDPP, containing two
repeating units are used, and the linear and branched side
chains are replaced by methyl and isobutyl groups, respectively,
in the actual calculations. Theoretical characterization of low-
lying electronic states of aNDTDTFBT and aNDTDPP is
performed using time-dependent density functional theory
(Figure 4a). However, only diffraction rings were observed in
PaNDTDPP (Figure 4b), implying that PaNDTDTFBT
possesses a more ordered and closer backbone structure than
PaNDTDPP, and hence the higher π-stacking crystallinity. The
crystalline nature of PaNDTDTFBT is also consistent with the
observation of a T at 300 °C from its DSC curve.
m
UV−Vis Absorption Spectroscopy. The absorption
spectra of the polymers are shown in Figure 5. Both of the
polymers exhibited two distinct bands in the absorption spectra.
Compared to PaNDTDTFBT showing the absorption maxima
at 600 nm in the solution and the solid state, PaNDTDPP
exhibited the apparent bathochromic shift of the intramolecular
charge transfer (ICT) band at 728 nm and showed a tailing of
the absorption band with a shoulder around 850 nm in the thin
film, which comes from the strong intermolecular interactions.
(
TD-DFT). The frontier orbitals of aNDTDTFBT and
aNDTDPP are shown in Figure 7, and the detailed results
are summarized in Table 2. The electron densities are
homogeneously distributed along the molecular backbone in
the HOMOs but located at the FBT or the DPP acceptor
regions in the LUMOs, indicating distinct intramolecular
charge transfer between donor and acceptor upon excitation.
The energy of HOMO−LUMO transition is calculated to be
opt
The optical band gaps (Eg ) calculated from the absorption
edges of the solid state spectra are determined to be 1.70 eV for
PaNDTDTFBT and 1.38 eV for PaNDTDPP. These results
Figure 3. Differential scanning calorimetry of (a) PaNDTDTFBT and (b) PaNDTDPP.
C
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Figure 4. 2D-WAXD patterns of the ordered phases of (a) PaNDTDTFBT and (b) PaNDTDPP after shearing. The arrows indicate the direction of
mechanical extruding force applied on the samples.
Figure 5. Normalized absorption spectra of PaNDTDTFBT and PaNDTDPP (a) in ODCB solutions and (b) in solid states.
Table 1. Summary of the Intrinsic Properties of the Polymers
λmax (nm)
polymer
M (kDa)
Td (°C)
ODCB
420
film
Egopt (eV) (film)
HOMO (eV)
LUMO (eV)
Egele (eV)
n
PaNDTDTFBT
67.8
447
420
606
410
738
1.70
−5.47
−3.50
1.97
6
00
400
28
PaNDTDPP
23.1
430
1.38
−5.34
−3.64
1.70
7
Transistor Characterization. The OFET mobilities of the
aNDT-based polymers were measured by the devices using a
bottom-gate, bottom-contact configuration with evaporated
gold source/drain electrodes (40 nm in thickness). All of the
output and transfer plots of the devices showed typical p-type
OFET characteristics (Figure 8). The hole mobilities were
calculated from the transfer characteristics of the devices in the
saturation regime. The OFET devices used SiO2 as gate
dielectric whose surfaces were modified with octadecyltrichlor-
osilane (ODTS) to form a self-assembled monolayer (SAM).
−
2
The hole mobility of the PaNDTDTFBT device is 4.7 × 10
2
−1 −1
5
cm V
s
with an on−off ratio of 1.0 × 10 . Moreover,
PaNDTDPP flanked with the shorter 2-butyloctyl groups at the
2
aNDT core possesses highest hole mobility, reaching 0.202 cm
−1
−1
4
V
s
with a on−off ratio of 1.0 × 10 , which is attributed to
the strong π−π stacking of the polymer backbone associated
Figure 6. Cyclic voltammograms of PaNDTDTFBT and PaNDTDPP.
with the rigid and coplanar structure of the aNDT units (Table
3
).
Photovoltaic Characteristics. Bulk heterojunction solar
7
05 nm for aNDTDTFBT and 739 nm for aNDTDPP, which
cells were fabricated on the basis of traditional ITO/
PEDOT:PSS/polymer:PCBM/Ca/Al conventional configura-
tion. The current density−voltage characteristics of the devices
are in acceptable agreement with their experimental ICT
absorption (650 and 730 nm in ODCB, respectively).
D
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16
OPV industry. The inverted devices were fabricated based on
the configuration of ITO/ZnO/polymer:PC BM/MoO /Ag.
71
3
The inverted device using PaNDTDTFBT:PC BM (1:1.2, in
71
wt %) blend with 5 vol % CN delivered a comparable PCE of
.50% with a high FF of 71%. By adding 5 vol % CN into
6
17
ODCB along with a buffer layer PFN to modify the work
funtion of ZnO, the device further achieved the highest PCE of
6
.86% with a good V of 0.84 V, an improved J of 11.38 mA/
oc sc
2
cm , and a higher FF of 71.8%. The corresponding external
quantum efficiencies (EQEs) for both the conventional and
inverted solar cells were measured under illumination of
monochromatic light to confirm the accuracy of the measure-
ments of the devices (Figure 9b). The Jsc calculated from
integration of the EQE spectra with an AM 1.5 G reference
spectrum agrees well with the Jsc obtained from the J−V
measurements. The morphology of the films was evaluated by
atomic force microscope (AFM) to understand the perform-
ance enhancement (Figure 10). Compared to the film on the
non-PFN-modified ZnO, the PaNDTDTFBT:PC BM blend
7
1
with 5 vol % additive CN film on top of the ZnO/PFN showed
smaller phase separation domains and surface roughness,
suggesting that the PFN interlayer could also influence the
domains of the active layer to form the more favorable
morphology.
Figure 7. HOMO and LUMO plots of the model compounds,
aNDTDTFBT (a, b), and aNDTDPP (c, d), respectively, calculated at
the level of B3LYP/6-31G(d) in ODCB.
CONCLUSION
■
In conclusion, the tetracyclic angular-shaped NDTs have
emerged as superb building blocks for creating a new class of
promising solution-processable materials. Side-chain engineer-
ing of the aNDT-based structures play a key role in optimizing
electronic/steric and intermolecular/intramolecular properties
associated with the device characteristics. We have developed a
facile strategy to construct the angular naphthadithiophene core
with regiospecific substitution of two aliphatic chains at its 4,9-
positions, leading to the two new PaNDTDTFBT and
PaNDTDPP D−A copolymers. The OPV devices based on
the PaNDTDTFBT:PC71BM blend delivered a promising PCE
of 6.52% in the conventional configuration and a higher PCE of
6.86% in the inverted architecture. Moreover, PaNDTDPP
having strong intermolecular interactions also achieved a high
under simulated 100 mW cm−2 AM 1.5 G illumination are
shown in Figure 9, and all the device parameters are shown in
Table 4. The device with PaNDTDPP:PC BM (1:2, in wt %)
6
1
2
blend exhibited a V of 0.72 V, a J of 6.90 mA/cm , an FF of
oc
sc
6
2.6%, and a PCE of 3.11%. On the other hand, the device
based on PaNDTDTFBT:PC BM (1:1, in wt %) blend
exhibited a V of 0.86 V, a J of 10.03 mA/cm , and a high FF
6
1
2
oc
sc
of 69.8% leading to a PCE of 6.02%. By adding 5 vol % 1-
chloronaphthalene (CN) as an additive, the
PaNDTDTFBT:PC BM (1:1, in wt %) device obtained a
6
1
2
higher J of 10.25 mA/cm , a similar FF of 69.9%, and a slightly
sc
higher PCE of 6.16%. More encouragingly, the device using
PaNDTDTFBT:PC BM (1:1, wt %) blend with 5 vol % CN
2
−1 −1
OFET mobility of 0.2 cm V s with an on−off ratio of 1.0 ×
10 . We envisioned that the 4,9-dialkyl aNDT unit could be
7
1
2
4
delivered superior performance with a J of 11.28 mA/cm , a
sc
Voc of 0.84 V, a high FF of 68.8%, and an improved PCE of
widely used to construct a new series of promising donor−
acceptor conjugated copolymers for solution-processable
devices.
6
.52%. This result reveals that the rigid and coplanar 4,9-dialkyl
aNDT unit with deep-lying HOMO level is a superior
component for donor−acceptor copolymers.
Compared to the conventional devices, the BHJ devices with
an inverted architecture possess much improved long-term
stability and better architecture for roll-to-roll fabrication in the
EXPERIMENTAL SECTION
■
Materials. Unless otherwise stated, all reactions were carried out
on a vacuum line under an N atmosphere. All chemicals are purchased
2
Table 2. Calculated HOMO/LUMO Energy, Excitation Energy, Oscillator Strength, and Configurations (with Largest CI
a
Coefficients) of the Excited State
excitation energy
b
c
compound
HOMO (eV)
LUMO (eV)
λexp (nm)
λcalc (nm)
oscillator strength
configurations
aNDTDTFBT
−5.00
−2.90
650
705
443
739
588
469
2.04
1.71
3.38
0.60
0.14
H → L
4
20
H → L + 2
H → L
aNDTDPP
−4.88
−2.94
730
6
60
10
H-1 → L + 1
H-5 → L
4
a
b
c
TD-B3LYP/6-31G(d), PCM = ODCB. Experimental values were measured in the o-dichlorobenzene solution. Configurations with major
contribution and largest coefficients in the CI expansion of each state.
E
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Figure 8. Typical output curves (a, c) and transfer plots (b, d) of the OFET devices based on PaNDTDTFBT and PaNDTDPP with the ODTS-
SAM layer, respectively.
Table 3. p-Type OFET Characteristics of PaNDTDTFBT and PaNDTDPP
mobility (cm V s−1
)
2
−1
polymer
SAM layer
annealing (°C)
Vth (V)
Ion/off
PaNDTDTFBT
PaNDTDTFBT
PaNDTDPP
bare SiO2
ODTS
200
200
200
200
−36
−25
−18
−12
1 × 103
1 × 105
7 × 10
1 × 104
0.0035
0.0470
0.0108
0.2020
3
bare SiO2
ODTS
PaNDTDPP
Figure 9. Current density−voltage characteristics (a) and EQE spectra (b) of the conventional devices (ITO/PEDOT:PSS/polymer:PCBM/Ca/Al)
−2
and inverted devices (ITO/ZnO/PFN/polymer:PC BM/MoO /Ag) devices under illumination of AM 1.5 G, 100 mW cm .
71
3
from Sigma-Aldrich, TCI, Alfa Aesar, or Acros and used as received
unless otherwise specified, and all solvents were distilled before using.
1.43 mmol) in THF (15 mL) and diisopropylamine (15 mL) was
added Pd(PPh ) Cl (250 mg, 0.36 mmol, 25 mol %), CuI (68 mg,
3
2
2
3
-Bromothiophene-2-carbaldehyde (1) and (E)-1,2-bis(3-bromothio-
0.36 mmol, 25 mol %), PPh (94 mg, 0.36 mmol, 25 mol %), and 4-
3
11
phen-2-yl)ethene (2) were synthesized as reported. Polymerization
was operated with a microwave reactor, CEM Discover System.
Polymer average molecular weights were determined by gel
permeation chromatography (GPC) with a Shodex KF-804 using
tetrahydrofuran (THF) as a solvent and calibrated with polystyrene
standards.
octyltetradec-1-yne (130 mg, 4.28 mmol). The mixture was stirred for
12 h at 80 °C, and water (15 mL) and hydrochloric acid (1 M, 15 mL)
were then added. The resulting mixture was extracted with EA (15 mL
× 3), and the combined organic layer was dried over anhydrous
MgSO
, filtered, and concentrated in vacuo. The residue was purified
4
by column chromatography on silica gel (hexane) to give a yellow oil
1
Synthesis of (E)-1,2-Bis(3-(4-octyltetradec-1-yn-1-yl)thiophen-2-
3a (yield: 88%). H NMR (CDCl , 400 MHz): δ 7.33 (s, 2 H), 7.05
3
yl)ethene (3a). To a deoxygenated solution of compound 2 (500 mg,
(d, J = 5.2 Hz, 2 H), 6.96 (d, J = 5.2 Hz, 2 H), 2.49 (d, J = 5.6 Hz, 4
F
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=
5.4 Hz, 2 H), 7.48 (d, J = 5.4 Hz, 2 H), 3.48 (d, J = 7.2 Hz, 4 H),
Table 4. Photovoltaic Characteristics
1
3
2
.20−2.10 (m, 2 H), 1.59−1.20 (m, 32 H), 0.95−0.85 (m, 12 H).
C
polymer:PCBM
(% wt ratio)
Voc
Jsc
FF
PCE
(%)
NMR (CDCl , 100 MHz): δ 137.31, 134.38, 134.17, 128.61, 125.63,
3
2
polymers
(V) (mA/cm ) (%)
1
24.88, 123.71, 41.87, 36.79, 32.66, 32.42, 31.89, 29.81, 28.25, 25.97,
a
+
PaNDTDPP
1:2
0.72
0.86
0.86
0.84
0.84
0.84
6.90
10.03
10.25
11.28
10.90
62.6
69.8
69.9
68.8
71.0
71.8
3.11
6.02
6.16
6.52
6.50
6.86
23.18, 22.66, 14.15, 14.10. HRMS (APCI, C H S H ) calcd,
577.3896; found, 577.3874.
38 56 2
a
PaNDTDTFBT
1:1
a
,
,
e
e
c
1
1
1
1
:1
:1
Synthesis of 2,7-Bis(trimethylstannyl)-4,9-bis(2-butyloctyl)-
naphtho[1,2-b:5,6-b′]dithiophene (Sn-aNDT-OD). To an anhydrous
THF (70 mL) solution of aNDT-OD (2.0 g, 2.54 mmol) was added n-
butyllithium (2.54 mL, 2.5 M) slowly at −78 °C. The stirring was
continued for 30 min at −78 °C and subsequently for 30 min at rt.
After cooling to −78 °C, trimethyltin chloride (7.62 mL, 1 M) was
added in one portion. The mixture was slowly warmed to rt and stirred
for 6 h. It was quenched with saturated NH Cl solution (10 mL). The
organic layer was separated, and the aqueous layer was extracted with
EA (10 mL). The combined organic extract was washed with brine
b
,
e
:1.2
:1.2
d
,
e
11.38
b
a
ITO/PEDOT:PSS/polymer:PC BM/Ca/Al. ITO/PEDOT:PSS/
6
1
c
polymer:PC BM/Ca/Al. ITO/ZnO/polymer:PC BM/MoO /Ag.
7
1
71
3
d
e
ITO/ZnO/PFN/polymer:PC BM/MoO /Ag. With 5 vol % CN
71
3
4
additive.
solution (20 mL × 3) and dried over anhydrous MgSO . After
4
filtration, the solvent was removed under vacuum to give a yellow oil
1
Sn-aNDT-OD (yield: 90%). H NMR (CDCl , 400 MHz): δ 7.81 (s, 2
3
H), 7.55 (s, 2 H), 3.48 (d, J = 7.2 Hz, 4 H), 2.15−2.05 (m, 2 H),
1
3
1
(
.50−1.20 (m, 64 H), 0.90−0.85 (m, 12 H), 0.48 (s, 18 H). C NMR
CDCl , 100 MHz): δ 139.50, 138.55, 138.47, 134.28, 131.73, 127.97,
3
1
2
24.36, 42.02, 36.96, 32.77, 32.73, 31.92, 31.90, 30.23, 29.73, 29.67,
9.64, 29.35, 29.32, 26.14, 26.12, 22.68, 22.66, 14.11, −8.28. HRMS
+
(APCI-H, C H S Sn H ): calcd, 1129.5696; found, 1129.5720.
60
104
2
2
Synthesis of 2,7-Bis(trimethylstannyl)-4,9-bis(2-butyloctyl)-
naphtho[1,2-b:5,6-b′]dithiophene (Sn-aNDT-BO). In a similar
manner to preparation of Sn-aNDT-OD, Sn-aNDT-BO was
synthesized from aNDT-BO (2.0 g, 3.47 mmol) (yield: 91%). H
1
Figure 10. AFM height images of the surface of (a)
PaNDTDTFBT:PC BM blend with 5 vol % CN on the ZnO (5.0
NMR (CDCl , 400 MHz): δ 7.82 (s, 2 H), 7.55 (s, 2 H), 3.5 (m, 4 H),
71
3
μm × 5.0 μm) and (b) PaNDTDTFBT:PC BM with 5 vol % CN on
2.20−2.08 (m, 2 H), 1.59−1.20 (m, 32 H), 0.90−0.80 (m, 12 H), 0.48
71
(s, 18 H). 13C NMR (CDCl , 100 MHz): δ 139.54, 138.58, 138.49,
the PFN-modified ZnO (5.0 μm × 5.0 μm). The surface roughness is
estimated to be 9.19 and 4.74 nm, respectively.
3
134.30, 131.77, 127.99, 124.38, 42.07, 36.93, 32.71, 32.56, 31.97,
2
9.91, 28.44, 26.09, 23.28, 22.68, 14.24, 14.13, −8.28. HRMS (APCI-
+
H, C H S Sn H ) calcd, 905.3192; found, 905.3213.
44
72
2
2
H), 1.70−1.60 (m, 2 H), 1.55−1.20 (m, 64 H), 0.95−0.80 (m, 12 H).
1
3
Synthesis of PaNDTDTFBT. To a 50 mL round-bottom flask was
introduced Sn-aNDT-OD (150 mg, 0.133 mmol), 4 (95.64 mg, 0.133
mmol), tris(dibenzylideneacetone)dipalladium (4.87 mg, 0.0053
mmol), tri(2-methylphenyl)phosphine (13.0 mg, 0.043 mmol), and
deoxygenated chlorobenzene (5.5 mL). The mixture was then
degassed by bubbling nitrogen for 10 min at room temperature. The
round-bottom flask was placed into the microwave reactor and
refluxed for 50 min under 270 W. Then, tributyl(thiophen-2-
yl)stannane (24.8 mg, 0.067 mmol) was added to the mixture
solution and reacted for 10 min under 270 W. Finally, 2-
bromothiophene (11.7 mg, 0.072 mmol) was added to the mixture
solution and reacted for 10 min under 270 W. The solution was added
into methanol dropwise. The precipitate was collected by filtration and
washed by Soxhlet extraction with acetone (24 h) and hexane (24 h)
sequentially. The product was redissolved in hot chlorobenzene (200
mL). The Pd−thiol gel (Silicycle Inc.) was added to the above
chlorobenzene solution to remove the residual Pd catalyst at 80 °C for
C NMR (CDCl , 100 MHz): δ 143.86, 130.50, 122.98, 122.05,
3
1
2
8
21.13, 94.05, 75.83, 37.24, 33.65, 31.90, 29.95, 29.69, 29.65, 29.35,
+
6.91, 23.88, 22.67, 14.10. HRMS (APCI, C H S H ): calcd,
5
4
88 2
01.6400; found, 801.6375.
Synthesis of (E)-1,2-Bis(3-(4-butyldec-1-yn-1-yl)thiophen-2-yl)-
ethane (3b). In a similar manner to preparation of 3a, 3b was
synthesized from compound 2 (500 mg, 1.43 mmol) (yield: 95%). H
1
NMR (CDCl , 400 MHz): δ 7.30 (s, 2 H), 7.05 (d, J = 5.2 Hz, 2 H),
3
6
.94 (d, J = 5.2 Hz, 2 H), 2.47 (d, J = 6.0 Hz, 4 H), 1.68−1.58 (m, 2
13
H), 1.50−1.22 (m, 32 H), 0.95−0.85 (m, 12 H). C NMR (CDCl ,
3
1
3
1
5
00 MHz): δ 143.87, 130.52, 123.03, 122.06, 121.16, 94.07, 75.84,
7.26, 33.69, 33.36, 31.92, 29.63, 29.14, 26.90, 23.90, 22.98, 22.69,
4.15, 14.10. HRMS (APCI, C H S H ): calcd, 577.3896; found,
77.3903.
Synthesis of 4,9-Bis(2-octyldodecyl)naphtho[1,2-b:5,6-b′]-
dithiophene (aNDT-OD). To a deoxygenated N-methyl-2-pyrrolidone
NMP, 10 mL) solution of compound 3a (2.0 g, 2.46 mmol) was
+
38
56 2
(
1
h. After filtration of solution and removal of the solvent under
added 1,8-diazabicycloundec-7-ene (DBU) (0.75 mL, 5.00 mmol).
The resulting mixture was refluxed for 2 days, cooled to rt, diluted with
water (100 mL), and extracted with EA (30 mL × 3). The combined
organic layer was washed with brine solution (30 mL) and dried over
reduced pressure, the polymer solution was added into methanol to
reprecipitate. The purified polymer was collected by filtration and
dried under vacuum for 1 day to give a purple black solid (140 mg,
1
yield 77%). M = 67.8 kDa; PDI = 1.2. H NMR (CDCl , 400 MHz):
anhydrous MgSO . After filtration, the solvent was removed under
n
3
4
δ 8.00−7.70 (br, 2 H), 7.60−7.30 (br, 4 H), 3.50−3.10 (br, 4 H),
vacuum, and the residue was purified by column chromatography on
1
3
1
.10−2.90 (br, 4 H), 2.10−2.00 (br, 2 H), 2.00−1.80 (br, 6H), 1.50−
.10 (br, 82 H), 1.00−0.70 (br, 18H).
Synthesis of PaNDTDPP. To a 50 mL round-bottom flask was
silica gel (hexane) to give a yellow oil aNDT-OD (yield: 65%). H
NMR (CDCl , 400 MHz): δ 7.83 (s, 2 H), 7.57 (d, J = 5.4 Hz, 2 H),
3
7
.48 (d, J = 5.4 Hz, 2 H), 3.46 (d, J = 7.2 Hz, 4 H), 2.2−2.05 (m, 2 H),
13
introduced Sn-aNDT-BO (100 mg, 0.110 mmol), 5 (75.60 mg, 0.110
mmol), tris(dibenzylideneacetone)dipalladium (4.00 mg, 0.0044
mmol), tri(2-methylphenyl)phosphine (10.7 mg, 0.035 mmol), and
deoxygenated chlorobenzene (5.0 mL). The mixture was then
degassed by bubbling nitrogen for 10 min at room temperature. The
round-bottom flask was placed into the microwave reactor and
refluxed for 50 min under 270 W. Then, tributyl(thiophen-2-
yl)stannane (20.5 mg, 0.055 mmol) was added to the mixture
solution and reacted for 10 min under 270 W. Finally, 2-
1
.50−1.18 (m, 64 H), 1.95−1.85 (m, 12 H). C NMR (CDCl , 100
3
MHz): δ 137.29, 134.36, 134.16, 128.59, 125.62, 124.87, 123.69, 41.87,
3
2
8
6.81, 32.67, 31.91, 31.89, 30.12, 29.65, 29.63, 29.60, 29.34, 29.30,
+
5.98, 22.68, 22.66, 14.10. HRMS (APCI, C H S H ): calcd,
5
4
88 2
01.6400; found, 801.6376.
Synthesis of 4,9-Bis(2-butyloctyl)naphtho[1,2-b:5,6-b′]-
dithiophene (aNDT-BO). In a similar manner to preparation of
aNDT-OD, aNDT-BO was synthesized from 3b (2.0 g, 3.47 mmol)
1
(
yield: 67%). H NMR (CDCl , 400 MHz): δ 7.84 (s, 2 H), 7.58 (d, J
3
G
DOI: 10.1021/acs.macromol.5b00098
Macromolecules XXXX, XXX, XXX−XXX

Macromolecules
Article
bromothiophene (9.7 mg, 0.060 mmol) was added to the mixture
solution and reacted for 10 min under 270 W. The solution was added
into methanol dropwise. The precipitate was collected by filtration and
washed by Soxhlet extraction with acetone (24 h) and hexane (24 h)
sequentially. The product was redissolved in hot chlorobenzene (200
mL). The Pd−thiol gel (Silicycle Inc.) was added to the above
chlorobenzene solution to remove the residual Pd catalyst at 80 °C for
PaNDTDTFBT /PC BM or PC BM (10 mg/mL; 1000 rpm). The
cathode made of calcium (35 nm thick) and aluminum (100 nm thick)
61
71
was evaporated through a shadow mask under high vacuum (<1 ×
−
6
10 Torr). Each device is constituted of 4 pixels defined by an active
2
area of 0.04 cm . Finally, the J−V curves were measured in air under
AM 1.5 G spectrum from a solar simulator.
1
9
For the inverted architectures, the ZnO precursor solution was
spin-coated onto ITO-coated glass and followed by thermal annealing
at 170 °C in air for 15 min to crystallize the film (thickness = ca. 50
nm). Subsequently, the PFN interlayer material was dissolved in
methanol in the presence of a small amount of acetic acid (2 μL/mL),
and its solution (concentration, 2 mg/mL) was spin-coated on top of
the ZnO layer. The same process for the active layer in the
1
h. After filtration of solution and removal of the solvent under
reduced pressure, the polymer solution was added into methanol to
reprecipitate. The purified polymer was collected by filtration and
dried under vacuum for 1 day to give a purple black solid (90 mg, yield
1
7
9
3
4%). M = 23.1 kDa; PDI = 3.1. H NMR (CDCl , 400 MHz): δ
n
3
.40−8.60 (br, 4 H), 7.80−7.40 (br, 4 H), 4.20−3.80 (br, 4 H), 3.60−
.20 (br, 4 H), 2.10−0.80 (br, 104 H).
conventional architecture was used for the inverted devices. A MoO
3
Instrumentation. H and 13C NMR spectra were measured using
1
layer (thickness = ca. 7 nm) and silver top anode (thickness = ca. 150
nm) were then thermally evaporated through a shadow mask under
a Varian 400 MHz instrument spectrometer and obtained in
−6
deuterated chloroform (CDCl ) with TMS as internal reference
high vacuum (<1 × 10 Torr) to complete the inverted devices. Each
3
2
unless otherwise stated, and chemical shifts (δ) are reported in parts
per million. Thermogravimetric analysis (TGA) was recorded on a
PerkinElmer Pyris under a nitrogen atmosphere at a heating rate of 10
device is constituted of 4 pixels defined by an active area of 0.04 cm .
Finally, the J−V curves were measured in air under AM 1.5 G
spectrum from a solar simulator.
°
C/min. Differential scanning calorimetry (DSC) was measured on a
TA Q200 Instrument under a nitrogen atmosphere at a heating rate of
ASSOCIATED CONTENT
■
1
0 °C/min. Absorption spectra were taken on a HP8453 UV−vis
*
S
Supporting Information
spectrophotometer. Electrochemical cyclic voltammetry was con-
ducted on a CH instruments electrochemical analyzer. A carbon
glass was used as the working electrode, Pt wire was used as the
1
H NMR and 13C NMR spectra of the unknown compounds
and copolymers. This material is available free of charge via the
Internet at http://pubs.acs.org.
+
counter electrode, and Ag/Ag electrode (0.01 M AgNO , 0.1 M
3
TBAP in acetonitrile) was used as the reference electrode in a solution
of acetonitrile with 0.1 M TBAPF (tetrabutylammonium hexafluor-
AUTHOR INFORMATION
Corresponding Author
E-mail: yjcheng@mail.nctu.edu.tw (Y.-J.C.).
6
■
*
ophosophate) at 80 mV/s. CV curves were calibrated using ferrocence
18
as the standard; the E1/2 of ferrocence is 0.09 V calculated as the
average of the two peak maxima E and E . The HOMO energy levels
pa
pc
onset
Notes
were obtained from the equation HOMO = −(E
.8) eV, and the LUMO energy levels were obtained from the
− E
+
1/2(ferrocene)
ox
4
The authors declare no competing financial interest.
onset
equation LUMO = −(E
− E
+ 4.8) eV. Bruker APEX
red
1/2(ferrocene)
DUO single crystal diffraction was employed for 2D-WAXD patterns,
and a INCOATEC 18 kW rotating I microfocus X-ray generator (Cu
Kα radiation λ = 0.1542 nm) attached to an APEX II CCD camera was
used. The exposure time to obtain high-quality patterns was 40 s.
Fabrication and Characterization of OFET Devices. Bottom-
ACKNOWLEDGMENTS
We thank the Ministry of Science and Technology, the Ministry
of Education, and the Center for Interdisciplinary Science
■
(
CIS) of the National Chiao Tung University, Taiwan, for
gate, bottom-contact OFETs were fabricated on Si/SiO substrates
financial support. We thank the National Center of High-
Performance Computing (NCHC) in Taiwan for computer
time and facilities. We thank Prof. Chien-Lung Wang at NCTU
for the help of the 2D-WAXD measurements. Y.J.C. acknowl-
edges the support from the Golden−Jade fellowship of the
Kenda Foundation, Taiwan.
2
with Ti/Au electrodes. Gold source and drain contacts (40 nm in
thickness) were deposited by vacuum evaporation after titanium on
octadecyltrichlorosilane (ODTS)-treated SiO /Si substrates through
2
the same shadow mask. The gold source and drain contacts were
treated with the pentafluorothiophenol SAM. The channel width and
length of the transistors are 1 mm and 0.1 mm, respectively. The
polymers were dissolved in chlorobenzene (10 mg/mL) and spin-
coated at 1000 rpm from a hot solution before being annealed at 200
REFERENCES
■
°
C for 10 min. Electrical measurements of OTFT devices were carried
out at room temperature under vacuum using an Agilent Technologies
156C. The field-effect mobility was calculated in the saturation
(1) (a) Cheng, Y.-J.; Yang, S.-H.; Hsu, C.-S. Chem. Rev. 2009, 109,
5868. (b) Scharber, M. C.; Mu
̈
hlbacher, D.; Koppe, M.; Denk, P.;
4
Waldauf, C.; Heeger, A. J.; Brabec, C. J. Adv. Mater. 2006, 18, 789.
(c) Wu, J.-S.; Cheng, S.-W.; Cheng, Y.-J.; Hsu, C.-S. Chem. Soc. Rev.
2015, in press. (d) Yu, G.; Gao, J.; Hummelen, J. C.; Wudl, F.; Heeger,
A. J. Science 1995, 270, 1789. (e) Zhao, X.; Zhan, X. Chem. Soc. Rev.
2011, 40, 3728.
2
regime by using the equation Ids = (μWC /2L)(V − V ) , where I is
the drain-source current, μ is the field-effect mobility, W is the channel
i
g
t
ds
width, L is the channel length, C is the capacitance per unit area of the
i
gate dielectric layer, V is the gate voltage, and V is threshold voltage.
g
t
Fabrication and Characterization of OPV Devices. ITO/glass
substrates were ultrasonically cleaned sequentially in detergent, water,
acetone, and isopropyl alcohol. Then, the substrates were covered by a
(2) (a) Chen, H.-Y.; Hou, J.; Zhang, S.; Liang, Y.; Yang, G.; Yang, Y.;
Yu, L.; Wu, Y.; Li, G. Nat. Photonics 2009, 3, 649. (b) Huo, L.; Zhang,
S.; Guo, X.; Xu, F.; Li, Y.; Hou, J. Angew. Chem., Int. Ed. 2011, 50,
9697. (c) Huo, L.; Hou, J. Polym. Chem. 2011, 2, 2453. (d) Son, H. J.;
Wang, W.; Xu, T.; Liang, Y.; Wu, Y.; Li, G.; Yu, L. J. Am. Chem. Soc.
2011, 133, 1885. (e) Wang, M.; Hu, X.; Liu, P.; Li, W.; Gong, X.;
Huang, F.; Cao, Y. J. Am. Chem. Soc. 2011, 133, 9638. (f) Zhou, H.;
Yang, L.; Stuart, A. C.; Price, S. C.; Liu, S.; You, W. Angew. Chem., Int.
Ed. 2011, 50, 2995. (g) Chen, Y.-L.; Chang, C.-Y.; Cheng, Y.-J.; Hsu,
C.-S. Chem. Mater. 2012, 24, 3964. (h) Ye, L.; Zhang, S.; Huo, L.;
Zhang, M.; Hou, J. Acc. Chem. Res. 2014, 47, 1595. (i) Zhang, M.; Guo,
X.; Zhang, S.; Hou, J. Adv. Mater. 2014, 26, 1118.
3
0 nm thick layer of PEDOT:PSS (Clevios P Al 4083 provided by H.
C. Stark) by spin-coating. After annealing in air at 150 °C for 10 min,
the samples were cooled to room temperature. Polymers were
dissolved in o-dichlorobenzene (ODCB), and PC BM or PC BM
61
71
(
purchased from UR) was added to reach the desired ratio. The
solution were stirred at 80 °C overnight and then heated at 110 °C for
h without cooling and filtration before spin-coating. The photoactive
1
layers were then spin-coated at different spin-coating speed without
annealing in a glovebox. The detailed processing parameters
(
polymer/ODCB concentration; spin coating speed) are shown as
(3) (a) Shinamura, S.; Miyazaki, E.; Takimiya, K. J. Org. Chem. 2010,
follows: PaNDTDPP/PC BM (5 mg/mL; 700 rpm) and
75, 1228. (b) Osaka, I.; Shinamura, S.; Abe, T.; Takimiya, K. J. Mater.
6
1
H
DOI: 10.1021/acs.macromol.5b00098
Macromolecules XXXX, XXX, XXX−XXX

Macromolecules
Article
Chem. C 2013, 1, 1297. (c) Wu, Z.; Yang, T.; Ong, B. S.; Liang, Y.;
Guo, X. Org. Photonics Photovolt. 2014, 2, 21.
(e) Duan, C.; Zhang, K.; Zhong, C.; Huang, F.; Cao, Y. Chem. Soc. Rev.
2013, 42, 9071. (f) Duan, C.; Cai, W.; Hsu, B. B. Y.; Zhong, C.; Zhang,
K.; Liu, C.; Hu, Z.; Huang, F.; Bazan, G. C.; Heeger, A. J.; Cao, Y.
Energy Environ. Sci. 2013, 6, 3022. (g) Gu, C.; Chen, Y.; Zhang, Z.;
Xue, S.; Sun, S.; Zhong, C.; Zhang, H.; Lv, Y.; Li, F.; Huang, F.; Ma, Y.
Adv. Energy Mater. 2014, 4, 1301771. (h) Long, G.; Wan, X.; Kan, B.;
Hu, Z.; Yang, X.; Zhang, Y.; Zhang, M.; Wu, H.; Huang, F.; Su, S.;
Cao, Y.; Chen, Y. ChemSusChem 2014, 7, 2358.
(
4) Osaka, I.; Abe, T.; Shinamura, S.; Takimiya, K. J. Am. Chem. Soc.
011, 133, 6852.
5) (a) Shinamura, S.; Osaka, I.; Miyazaki, E.; Nakao, A.; Yamagishi,
M.; Takeya, J.; Takimiya, K. J. Am. Chem. Soc. 2011, 133, 5024.
b) Nakano, M.; Shinamura, S.; Houchin, Y.; Osaka, I.; Miyazaki, E.;
Takimiya, K. Chem. Commun. 2012, 48, 5671.
6) (a) Osaka, I.; Houchin, Y.; Yamashita, M.; Kakara, T.; Takemura,
N.; Koganezawa, T.; Takimiya, K. Macromolecules 2014, 47, 3502.
b) Osaka, I.; Komatsu, K.; Koganezawa, T.; Takimiya, K. Sci. Technol.
2
(
(
(
(18) Gagne, R. R.; Koval, C. A.; Lisensky, G. C. Inorg. Chem. 1980,
19, 2854.
(19) Sun, Y.; Seo, J. H.; Takacs, C. J.; Seifter, J.; Heeger, A. J. Adv.
(
Adv. Mater. 2014, 15, 024201. (c) Graham, K. R.; Cabanetos, C.;
Jahnke, J. P.; Idso, M. N.; El Labban, A.; Ngongang Ndjawa, G. O.;
Heumueller, T.; Vandewal, K.; Salleo, A.; Chmelka, B. F.; Amassian,
A.; Beaujuge, P. M.; McGehee, M. D. J. Am. Chem. Soc. 2014, 136,
Mater. 2011, 23, 1679.
9608. (d) Li, J.; Qiao, X.; Xiong, Y.; Li, H.; Zhu, D. Chem. Mater. 2014,
26, 5782. (e) Mei, J.; Bao, Z. Chem. Mater. 2014, 26, 604.
(
7) (a) Nakano, M.; Shinamura, S.; Sugimoto, R.; Osaka, I.; Miyazaki,
E.; Takimiya, K. Org. Lett. 2012, 14, 5448. (b) Shinamura, S.;
Sugimoto, R.; Yanai, N.; Takemura, N.; Kashiki, T.; Osaka, I.;
Miyazaki, E.; Takimiya, K. Org. Lett. 2012, 14, 4718.
(
8) Osaka, I.; Abe, T.; Shimawaki, M.; Koganezawa, T.; Takimiya, K.
ACS Macro Lett. 2012, 1, 437.
9) Osaka, I.; Kakara, T.; Takemura, N.; Koganezawa, T.; Takimiya,
K. J. Am. Chem. Soc. 2013, 135, 8834.
10) (a) Shi, S.; Jiang, P.; Yu, S.; Wang, L.; Wang, X.; Wang, M.;
(
(
Wang, H.; Li, Y.; Li, X. J. Mater. Chem. A 2013, 1, 1540. (b) Shi, S.;
Xie, X.; Jiang, P.; Chen, S.; Wang, L.; Wang, M.; Wang, H.; Li, X.; Yu,
G.; Li, Y. Macromolecules 2013, 46, 3358.
(
11) Cheng, S.-W.; Chiou, D.-Y.; Lai, Y.-Y.; Yu, R.-H.; Lee, C.-H.;
Cheng, Y.-J. Org. Lett. 2013, 15, 5338.
12) (a) Bronstein, H.; Frost, J. M.; Hadipour, A.; Kim, Y.; Nielsen,
(
C. B.; Ashraf, R. S.; Rand, B. P.; Watkins, S.; McCulloch, I. Chem.
Mater. 2013, 25, 277. (b) Jheng, J. F.; Lai, Y. Y.; Wu, J. S.; Chao, Y. H.;
Wang, C. L.; Hsu, C. S. Adv. Mater. 2013, 25, 2445.
(
13) (a) Wu, J.-S.; Lin, C.-T.; Wang, C.-L.; Cheng, Y.-J.; Hsu, C.-S.
Chem. Mater. 2012, 24, 2391. (b) Meager, I.; Ashraf, R. S.; Mollinger,
S.; Schroeder, B. C.; Bronstein, H.; Beatrup, D.; Vezie, M. S.;
Kirchartz, T.; Salleo, A.; Nelson, J.; McCulloch, I. J. Am. Chem. Soc.
2
(
013, 135, 11537.
14) Shi, S.; Xie, X.; Qu, R.; Chen, S.; Wang, L.; Wang, M.; Wang,
H.; Li, X.; Yu, G. RSC Adv. 2013, 3, 18944.
15) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
(
Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci,
B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H.
P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima,
T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery Jr., J. A.;
Peralta, J. E.; Ogliaro, F.; Bearpark, M. J.; Heyd, J.; Brothers, E. N.;
Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.;
Raghavachari, K.; Rendell, A. P.; Burant, J. C.; Iyengar, S. S.;
Tomasi, J.; Cossi, M.; Rega, N.; Millam, N. J.; Klene, M.; Knox, J. E.;
Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.;
Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.;
Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.;
Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A.
̈
D.; Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J.
Gaussian 09; Gaussian, Inc.: Wallingford, CT, 2009.
(
16) (a) Xu, Z.; Chen, L.-M.; Yang, G.; Huang, C.-H.; Hou, J.; Wu,
Y.; Li, G.; Hsu, C.-S.; Yang, Y. Adv. Funct. Mater. 2009, 19, 1227.
b) Hau, S. K.; Yip, H.-L.; Baek, N. S.; Zou, J.; O’Malley, K.; Jen, A. K.
(
Y. Appl. Phys. Lett. 2008, 92, 253301. (c) Hsieh, C.-H.; Cheng, Y.-J.; Li,
P.-J.; Chen, C.-H.; Dubosc, M.; Liang, R.-M.; Hsu, C.-S. J. Am. Chem.
Soc. 2010, 132, 4887.
(
17) (a) Huang, F.; Wu, H.; Wang, D.; Yang, W.; Cao, Y. Chem.
Mater. 2004, 16, 708. (b) Huang, F.; Wu, H.; Cao, Y. Chem. Soc. Rev.
010, 39, 2500. (c) He, Z.; Zhong, C.; Huang, X.; Wong, W. Y.; Wu,
2
H.; Chen, L.; Su, S.; Cao, Y. Adv. Mater. 2011, 23, 4636. (d) He, Z.;
Zhong, C.; Su, S.; Xu, M.; Wu, H.; Cao, Y. Nat. Photonics 2012, 6, 591.
I
DOI: 10.1021/acs.macromol.5b00098
Macromolecules XXXX, XXX, XXX−XXX