Tuning photovoltaic performance of 9,9-dioctylfluorene-alt-5,7- bis(thiophen-2-yl)-2,3-biphenylthieno[3,4-b]pyrazine copolymeric derivatives by attaching additional donor units in pendant phenyl ring

Article abstract of DOI:10.1002/pola.26284

A class of the 9,9-dioctylfluorene-alt-5,7-bis(thiophen-2-yl)-2,3- biphenylthieno [3,4-b]pyrazine copolymeric derivatives (PFO-3ThPz-D) attaching additional donor (D) units in the pendant phenyl ring with a D-A D structure was synthesized and investigated, where the additional D unit is a substituent group of fluorene, carbazole, and triphenylamine (Tpa). Their photovoltaic properties were significantly tuned by these pending donor units. Among these copolymers, the PFO-3ThPz-Tpa exhibited the best photovoltaic properties in the bulk heterojunction polymeric solar cells (BHJ-PSC). The maximum power conversion efficiency (PCE) of 2.09% and the highest circuit current density (J_sc) of 7.91 mA/cm² were obtained in the cell using a blend of PFO-3ThPz-Tpa and PC₆₀BM (1:3, w/w) as active layer, which are 2.5 and 1.8 times higher than those corresponding levels in the other cell using the parent PFO-3ThPz-Ph copolymer instead of PFO-3ThPz-Tpa as donor, respectively. While PC₆₀BM was replaced by PC₇₀BM, the PFO-3ThPz-Tpa-based BHJ-PSC exhibited better photovoltaic properties with PCE of 3.08% and J_sc of 10.3 mA/cm². This work demonstrated that attaching donor units into the D-A-based copolymeric side-chain is a simple and effective method to improve the photovoltaic properties for the resulting copolymers. Copyright

Full text of DOI:10.1002/pola.26284

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
Tuning Photovoltaic Performance of 9,9-Dioctylfluorene-alt-5,7-
bis(thiophen-2-yl)-2,3-biphenylthieno[3,4-b]pyrazine Copolymeric
Derivatives by Attaching Additional Donor Units in Pendant Phenyl Ring
Jianmin Li, Xianping Deng, Zhiyong Zhang, Yafei Wang, Yu Liu, Keqi He, Ying Huang,
Qiang Tao, Lixia Quan, Weiguo Zhu
Key Laboratory of Environment-Friendly Chemistry and Application in Ministry of Education, College of Chemistry, Xiangtan
University, Xiangtan 411105, China
Correspondence to: Y. Wang (E-mail: qiji830404@hotmail.com) or W. Zhu (E-mail: zhuwg18@126.com)
Received 4 April 2012; accepted 25 June 2012; published online
DOI: 10.1002/pola.26284
ABSTRACT: A class of the 9,9-dioctylfluorene-alt-5,7-bis(thiophen-
2-yl)-2,3-biphenylthieno [3,4-b]pyrazine copolymeric derivatives
(PFO-3ThPz-D) attaching additional donor (D) units in the pend-
ant phenyl ring with a D-A D structure was synthesized and
investigated, where the additional D unit is a substituent group
of fluorene, carbazole, and triphenylamine (Tpa). Their photovol-
taic properties were significantly tuned by these pending donor
units. Among these copolymers, the PFO-3ThPz-Tpa exhibited
the best photovoltaic properties in the bulk heterojunction poly-
meric solar cells (BHJ-PSC). The maximum power conversion
efficiency (PCE) of 2.09% and the highest circuit current density
(Jsc) of 7.91 mA/cm2 were obtained in the cell using a blend of
PFO-3ThPz-Tpa and PC60BM (1:3, w/w) as active layer, which are
2.5 and 1.8 times higher than those corresponding levels in the
other cell using the parent PFO-3ThPz-Ph copolymer instead of
PFO-3ThPz-Tpa as donor, respectively. While PC60BM was
replaced by PC70BM, the PFO-3ThPz-Tpa-based BHJ-PSC exhib-
ited better photovoltaic properties with PCE of 3.08% and Jsc of
10.3 mA/cm2. This work demonstrated that attaching donor
units into the D-A-based copolymeric side-chain is a simple and
effective method to improve the photovoltaic properties for the
C
V
resulting copolymers. 2012 Wiley Periodicals, Inc. J Polym Sci
Part A: Polym Chem 000: 000–000, 2012
KEYWORDS: high-performance
polymer; dioctylfluorene-alt-
5,7-bis(thiophen-2-yl)-2,3-biphenylthieno[3,4-b]pyrazine copoly-
mers; functionalization of polymers; synthesis; polymer solar
cells
INTRODUCTION In the past decade, polymer solar cells
(PSCs) have received a great deal of attention as a potential
renewable energy source because of their advantages such
as low cost, light weight, mechanical flexibility, and easy
manufacture by high-throughput and large-area reel-to-reel
coating processes.1–4 To achieve high-efficiency PSCs, most of
conjugated polymers with low band-gap, strong solar absorp-
tion, and high charge-carrier mobility have been devel-
oped.5–7 In these reported photovoltaic polymers, the low
band-gap polymers containing alternating electron-rich do-
nor (D) and electron-deficient acceptor (A) units in the poly-
mer chain were specially focused.8–16 Using this class of low
band-gap polymers as donor materials and taking intensive
device engineering, the PSCs exhibited ascending power con-
version efficiency (PCE) high over 6%.17–20 Recently, the PSC
with highest PCE of 8.37% was demonstrated by He et al.21
(Eg) and is available to construct photovoltaic polymers.3 As
a result, various D-p-A-based polymers were developed using
thieno-[3,4-b]pyrazine as acceptor unit, together with
fluorene (Fl) or carbazole (Cz) as donor unit, and thiophene
as p-spacer in main-chain.22–24 By attaching some functional
groups, such as phenyl and alkyl, into the top pyrazine ring,
the formed D-p-A-based polymers exhibited variational band
gaps and growing PCEs in PSCs. For example, diethylhex-
ylfluorene-alt-5,7-bis-(thiophen-2-yl)-2,3-biphenyl-thieno[3,4-
b]pyrazine copolymer (TP2) displayed an Eg level of 1.74 eV
and a PCE of 0.89% in PSCs.22 While attaching C-8 alkyl into
the pendant phenyl ring and using n-octyl instead of diethyl-
hexyl in the 9-position of fluorene in TP2, the resulting
copolymers of APFO-Green5 and APFO-Green6 showed a
lower Eg level of 1.6 eV and a higher PCE of 2.2%.23
To further study the influence of functional groups in the
pendant phenyl rings of thieno[3,4-b]pyrazine unit on photo-
voltaic performance of their corresponding copolymers,
Among these D-A-based polymers, the electron-deficient
thieno[3,4-b]pyrazine unit is a quite favorable acceptor unit
because it contains a N-heterocycle with narrow energy-gap
in this article,
a
class of 9,9-dioctylfluorene-alt-5,7-
C
V
2012 Wiley Periodicals, Inc.
WWW.MATERIALSVIEWS.COM
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 000, 000–000
1

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
SCHEME 1 Synthesis of the PFO-3ThPz-D and PFO-3ThPz-Ph copolymers.
bis(thiophen-2-yl)-2,3-biphenylthieno[3,4-b] pyrazine copoly-
meric derivatives (PFO-3ThPz-D) with a D-A/|D structure
containing additional D units in the 4-positions of the pend-
ant two phenyl rings was synthesized, where the additional
D units are substituent groups of Fl, Cz, and triphenylamine
(Tpa), respectively. For comparison, their parental counter-
part of 9,9-dioctyl fluorene-alt-5,7-bis-(thiophen-2-yl)-2,3-
biphenyl-thieno[3,4-b]pyrazine (PFO-3ThPz-Ph), without any
additional D units was also prepared for comparison. Their
synthetic routes are shown in Scheme 1. Attaching the addi-
tional D units into side-chain of the A units in the parent D-
p-A-based copolymer is expected to further enhance the
2
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 000, 000–000

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
absorbed solar radiation and improve the PCEs for the
resulting copolymers in PSCs. Morever, adding octyl or
octoxy group into the end of the additional D units is sug-
gested to be available for improving the solubility and dis-
persibility of the copolymers. Although most of the reported
copolymers have a D-p-A structure in main-chain,25–27 the
copolymers with a D-A/|D structure is rare yet.28–32 As
expected, these designed PFO-3ThPz-D copolymeric deriva-
tives exhibited significantly improved photovoltaic perform-
ances than the parent PFO-3ThPz-Ph copolymer in the bulk
heterojunction (BHJ) PSCs using a blend of copolymers do-
nor and PC60BM acceptor (1:3, w/w) as the active layer. The
maximum circuit current density (Jsc) of 7.91 mA/cm2 and
the maximum PCE of 2.09% were obtained in the PFO-
3ThPz-Tpa-based device, which are 1.8 and 2.4 times higher
than the corresponding levels for the PFO-3ThPz-Ph-based
device, respectively. When PC60BM was replaced by PC71BM,
the PFO-3ThPz-Tpa-based device exhibited better photovol-
taic performances with Jsc of 10.3 mA/cm2, fill factor (FF) of
40%, and PCE of 3.08%. Therefore, introducing the addi-
tional D unit into the side-chain of the A unit in the D-p-A-
based copolymers is available to significantly improve photo-
voltaic performance for its resulting copolymers.
FIGURE 1 TGA curves of the PFO-3ThPz-D and PFO-3ThPz-Ph
copolymers at
atmosphere.
a
scan rate of 20ꢀC minꢂ1 under nitrogen
available to improve the solubility of copolymers and facili-
tate the coupling reaction.
Thermal Stability
The thermal stability of PFO-3ThPz-D and PFO-3ThPz-Ph
was investigated by thermogravimetric analysis (TGA) under
a nitrogen atmosphere. The recorded TGA curves are shown
in Figure 1, and their corresponding thermal degradation
temperatures (Td) at 5% weight loss are also summarized in
Table 1. The Td levels high over 391ꢀC are observed for
these copolymers. Furthermore, all PFO-3ThPz-D copolymers
have higher Td level than the PFO-3ThPz-Ph copolymer.
Therefore, introducing additional donor units into the pend-
ant phenyl rings of thieno-[3,4-b]pyrazine segment has a
positive effect on enhancing thermal stability for the result-
ing copolymers.
RESULTS AND DISCUSSION
Synthesis and Characterization
The copolymers of PFO-3ThPz-D (D ¼ Fl, Cz, Tpa) and their
parental counterpart of PFO-3ThPz-Ph were synthesized by a
palladium-catalyzed Suzuki coupling reaction and end-
capped successively by phenyl-boronic acid and bromo-ben-
zene referred to Zhou et al.22 and Mammo et al.23 works.
Their chemical structures were confirmed by 1H NMR and
13C NMR. The yield of PFO-3ThPz-D is mediate and higher
than that of PFO-3ThPz-Ph. In additional, their number-aver-
age molecular weights (Mn) and weight-average molecular
weights (Mw) as well as polydispersity indices (PDIs) were
determined by gel permeation chromatography (GPC) using
polystyrene as standard calibration. The resulting data are
shown in Table 1. Higher Mn and Mw are also observed in
these PFO-3ThPz-D copolymers rather than PFO-3ThPz-Ph.
Higher yields and average molecular weights for these PFO-
3ThPz-D copolymers could be attributed to the increased
alkyl or alkoxyl chains in the pending D units, which are
Dispersible Property
As the morphography of the active layer is an important factor
affecting the device performance, we investigated dispersible
property of these copolymers in PC60BM acceptor. The typical
blend films of these copolymers and PC60BM were spun on irid-
ium tin oxide (ITO) glass substrates, in which the weight ratio
between copolymer and PC60BM is 1:3. Their surface morpholo-
gies were recorded in Figure 2 by atomic force microscopy
(AFM) in a surface area of 5 ꢁ 5 lm2 at a tapping mode. The
roughness of the PFO-3ThPz-Fl:PC60BM, PFO-3ThPz-Cz:PC60BM,
PFO-3ThPz-Tpa:PC60BM, and PFO-3ThPz-Ph:PC60BM, blend films
are observed to be 0.55, 0.64, 0.46, and 0.43 nm, respectively.
All films show a smooth surface and small degree of phase
separation. It indicates that the introducing additional donor
units in 2,3-position of pyrazine have few effects on the
dispersibility of its copolymers in PC60BM acceptor.
TABLE 1 Physical Properties of the PFO-3ThPz-D and PFO-
3ThPz-Ph Copolymers
Polymer
Mn (kg/mol)a Mw (kg/mol)a PDIa Td (ꢀC)b
PFO-3ThPz-Fl
PFO-3ThPz-Cz
14.2
10.3
18.1
16.7
68.4
9.1
1.3
1.6
1.5
1.3
422
433
424
391
Optical Property
PFO-3ThPz-Tpa 44.6
The UV–vis absorption spectra of PFO-3ThPz-D and PFO-
3ThPz-Ph in dichloromethane solution (DCM, 10ꢂ5 M) and in
their neat films are shown in Figure 3, respectively. Their
UV–vis absorption data are summarized in Table 2. Two dis-
tinct UV–vis absorption peaks from 400 nm to 700 nm are
PFO-3ThPz-Ph
6.8
a
Calculated from gel permeation chromatography (eluent: THF; polysty-
rene standard).
Temperꢂa1ture at 5% weight loss measured by TGA at a heating rate of
b
20ꢀC min under nitrogen atmosphere.
WWW.MATERIALSVIEWS.COM
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 000, 000–000
3

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
FIGURE 2 AFM images of the PFO-3ThPz-Fl:PC60BM (a), PFO-3ThPz-Cz:PC60BM (b), PFO- 3ThPz-Tpa:PC60BM (c), and PFO-3ThPz-
Ph:PC60BM (d) blend films at a 1:3 weight radio between polymer and PC60BM.
observed for these copolymers in the thin films, which are a
common feature of the D-A copolymers.33–35 According to
the literatures, the peak at longer wavelength about 666 nm
is attributed to the intramolecular charge transfer transition
between the donor unit of dioctylfluorene and the acceptor
unit of 5,7-bis(thiophen-2-yl)-2,3-biphenylthieno[3,4-b]pyraz-
ine in the main-chain,35,36 and the other peak at short wave-
length about 435 nm is assigned to the localized p–p* transi-
tion.22,35,37 When compared with PFO-3ThPz-Ph, these PFO-
3ThPz-D copolymers display an additional absorption peak
at high-lying region about 307 nm, which is assigned to p–p*
transition of the attached D units in the side-chain of the A
unit. Thus, both D-A units in the main chain and side chain
have contribution to the broad absorption bands of the PFO-
3ThPz-D polymers. Furthermore, these PFO-3ThPz-D
polymers presented apparently red shift than the parent
PFO-3ThPz-Ph polymer in the absorption threshold. The
additional absorption and red-shift absorption threshold are
beneficial to harvest sunlight for PFO-3ThPz-D. On the other
hand, these absorption profiles accompany with somewhat
red shift in the neat films relative to those in dilute DCM so-
lution for the PFO-3ThPz-D. This indicates that intermolecu-
lar self-organization behavior should exist for PFO-3ThPz-D
in the films due to the stronger D-A effect.38 Incorporating
additional D units in the side-chain of the D-A-based copoly-
mer can further decrease the band gap, optimize the energy
levels, and enlarge the responsive wavelength region.
Electrochemical Study
The electrochemical behaviors of PFO-3ThPz-D and PFO-
3ThPz-Ph-based neat films were investigated by cyclic vol-
tammetry (CV). The CV measure was carried out in a typical
4
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 000, 000–000

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
important prerequisite for p-type semiconductor materials.
The onset oxidation potentials (Eox) and reduction potentials
(Ered) for these PFO-3ThPz-D copolymers were observed in a
range of 0.80–0.87 V and ꢂ0.89 to ꢂ0.97 V versus saturated
calomel electrode (SCE), respectively. Thus, the HOMO and
LUMO energy levels (EHOMO and ELUMO) were calculated
according to the empirical formulas EHOMO ¼ ꢂ(Eox þ 4.40)
eV and ELUMO ¼ ꢂ(Ered þ 4.40) eV, respectively.35 The elec-
trochemical bandgaps (Eg) were calculated based on the for-
mula of Eg ¼ ELUMO ꢂ EHOMO and the optical band gaps
(Egopt) were estimated the onset absorption edges of the
thin film spectra.
The results show that the EHOMO and ELUMO levels of the
PFO-3ThPz-D copolymers located in a range of ꢂ5.23 to
ꢂ5.27 eV and ꢂ3.43 to ꢂ3.48 eV, respectively. It is evident
that the EHOMO levels lower and the ELUMO levels raise for
PFO-3ThPz-D relative to the corresponding energy levels for
PFO-3ThPz-Ph. The rising ELUMO levels are available to facili-
tate energetically electron transfer as the ELUMO levels for
PFO-3ThPz-D are higher than those of PC60BM (ꢂ3.9 eV)
and PC71BM (ꢂ3.8 eV) acceptors in the cells. The lower
EHOMO levels are useful to increase the open-circuit voltage
for their cells. For this reason, introducing additional donor
units into the pendant phenyl rings of thieno[3,4-b]pyrazine
segment can rightly tune the HOMO and LUMO energy levels
which is in favor of improving the photovoltaic performance
for the D-A-based copolymers.
Photovoltaic Properties
To investigate the photovoltaic properties of the PFO-3ThPz-
D and PFO-3ThPz-Ph copolymers, their BHJ-based PSCs with
a sandwich structure of ITO/PEDOT:PSS/copolymer:PC60BM/
LiF/Al were fabricated. The J–V characteristics of these cells
are shown in Figures 4 and 5 measured under the illumina-
tion of AM 1.5 G (100 mW mꢂ2) from a solar simulator, and
the corresponding photovoltaic data are summarized in
Table 3. The PCE of 1.19–2.09%, Jsc of 4.36–7.91 mA/cm2,
open-circuit voltage (Voc) of 0.73–0.79 V, and FF of 0.32–0.39
were obtained in these PFO-3ThPz-D-based cells. It is
obvious that the photovoltaic performance of the PFO-
3ThPz-D-based cells were significantly improved relative to
FIGURE 3 UV–vis absorption spectra of the PFO-3ThPz-D and
PFO-3ThPz-Ph copolymers in CH2Cl2 solution (a) and in their
neat films (b).
three-electrode electrochemical cell. The resulting CV data
are listed in Table 2. All these copolymers presented a stable
and reversible redox process, which is suggested to be
TABLE 2 Optical and Electrochemical Properties of the PFO-3ThPz-D and PFO-3ThPz-Ph Copolymers
UV–Vis Absorption Spectra
Electrochemical Dataa
opt
Eg
Eox
EHOMO
Ered
ELUMO
Eg
Polymer
kmax (nm)b [emax (L molꢂ1 cmꢂ1)]
kmax (nm)c
(eV)d
(V)
(eV)
(V)
(eV)
(eV)
PFO-3ThPz-Fl
PFO-3ThPz-Cz
316 (1.9 ꢁ 105), 423 (1.7 ꢁ 105), 652 (6.1 ꢁ 104)
299 (1.1 ꢁ 105), 428 (8.9 ꢁ 104), 649 (3.2 ꢁ 104)
317, 428, 666 1.56
301, 430, 665 1.55
0.83 ꢂ5.23
0.87 ꢂ5.27
0.85 ꢂ5.25
ꢂ0.92 ꢂ3.48
ꢂ0.95 ꢂ3.45
ꢂ0.97 ꢂ3.43
1.75
1.82
1.82
PFO-3ThPz-Tpa 299 (1.2 ꢁ 105), 365 (1.3 ꢁ 105), 445 (1.4 ꢁ 105),
300, 383,
447, 677
1.57
660 (6.1 ꢁ 104)
PFO-3ThPz-Ph
423 (9.5 ꢁ 104), 635 (5.6 ꢁ 104)
435, 655
1.54
0.80 ꢂ5.20
ꢂ0.89 ꢂ3.51
1.69
a
The Eox and Ered were measured by cyclic voltammetry in CH3CN, respectively. EHOMO and ELUMO levels were calculated based on the formula,
EHOMO ¼ ꢂ(Eox þ 4.40) eV and ELUMO ¼ ꢂ(Ered þ 4.40) eV. The electrochemical band gap was calculated on the formula, Eg ¼ ELUMO ꢂ EHOMO
.
b
Measured in CH2Cl2 at a concentration of 10ꢂ6 mol/L.
c
Measured in spun-cast polymer films.
d
opt
Estimated according to the formula Eg ¼ 1,240/kedge, kedge is a onset wavelength of the optical absorption in thin film.
WWW.MATERIALSVIEWS.COM
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 000, 000–000
5

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
CONCLUSIONS
In summary,
a
class of 9,9-dioctylfluorene-alt-5,7-bis
(thiophen-2-yl)-2,3-biphenylthieno [3,4-b] pyrazine copoly-
meric derivatives containing additional donor units in the
pendant two phenyl rings, that is, PFO-3ThPz-Fl, PFO-3ThPz-
Cz, and PFO-3ThPz-Tpa, was obtained and characterized. Our
research results show that the photovoltaic properties for
these copolymeric derivatives were significantly improved
relative to those for the parental counterpart of PFO-3ThPz-
Ph. The maximum PCE of 2.09% and the highest Jsc of 7.91
mA cmꢂ2 were exhibited in the PFO-3ThPz-Tpa-based BHJ-
PSC using a blend of PFO-3ThPz-Tpa and PC60BM as active
layer (1:3 w/w). The PCE and Jsc levels are 2.5 and 1.8 times
higher than those corresponding levels in the PFO-3ThPz-Ph-
based cell with the same cell structure, respectively. While
using PC71BM instead of PC60BM as acceptor, the PFO-
3ThPz-Tpa-based cell exhibited better photovoltaic perform-
ances with PCE of 3.08%, Jsc of 10.2 mA/cm2, and FF of
40%. This work demonstrated that attaching additional do-
nor units into the acceptor unit of the D-A-based copolymers
is a simple and effective method to tune UV–vis absorption
and electrochemical properties, further improve photovoltaic
performance for the resulting copolymers.
FIGURE 4 J–V characteristics of the PFO-3ThPz-D and PFO-
3ThPz-Ph copolymers-based BHJ-PSCs with a structure of ITO/
PEDOT:PSS/copolymers:PC60BM (1:3, w/w)/LiF/Al under the illu-
mination of AM 1.5 G from a solar simulator (100 mW cmꢂ2).
those of the PFO-3ThPz-Ph-based cell. The maximum PCE of
2.09% and the highest Jsc of 7.91 mA cmꢂ2 were exhibited
in the cell using a blend of PFO-3ThPz-Tpa and PC60BM (1:3
w/w) as the active layer, which are 2.5 and 1.8 times higher
than the corresponding levels in the PFO-3ThPz-Ph-based
cell with the same cell structure, respectively. It demon-
strates that attaching additional donor units into the pendant
phenyl rings of thieno[3,4-b]pyrazine segment is very benefi-
cial to improve the photovoltaic performances for the D-A-
based copolymers. In addition, by further device optimiza-
tion using PC71BM instead of PC60BM as acceptor, it was
observed that the cell containing the PFO-3ThPz-Tpa:PC71BM
blend (1:3 w/w) exhibited better photovoltaic performances
with PCE of 3.08%, Jsc of 10.2 mA/cm2, and FF of 40%.
EXPERIMENTAL
Measurement and Characterization
1H NMR and 13C NMR spectra were recorded on a Bruker
AV-400 using deuterated chloroform as solvent. Elemental
analyses were carried out on a flash EA 1112 elemental ana-
lyzer. Mass spectra were recorded on a Bruker MALDI-TOF
instrument. Average molecular weights and PDI of copoly-
mers were determined by a Waters 1515 GPC using tetrahy-
drofuran (THF) as an eluent and polystyrene as a standard.
TGAs were performed on a Netzsch TG 209 analyzer under
nitrogen atmosphere at a heating rate of 20ꢀC minꢂ1. Surface
morphologies were recorded by AFM on a Veeco, DI Multi-
mode NS-3D apparatus in a trapping mode under normal air
condition at room temperature (RT). UV–vis spectra were
measured on a Perkin-Elmer Lamada 25 spectrometer. CV
measurements were conducted using a EG&G Princeton
Applied Research Model 273 potentiostat/galvanostat
equipped with an electrochemical analysis system software
TABLE 3 Photovoltaic Performances of the PFO-3ThPz-D and
PFO-3ThPz-Ph Copolymers-Based BHJ-PSCs
Polymer
Jsc (mA/cm2)
Voc (V)
PCE (%)
FF
PFO-3ThPz-Fla
PFO-3ThPz-Cza
PFO-3ThPz-Tpaa
PFO-3ThPz-Pha
PFO-3ThPz-Tpab
a
4.36
4.66
7.91
4.39
10.24
0.73
0.79
0.76
0.73
0.76
1.23
1.19
2.09
0.85
3.08
0.39
0.32
0.35
0.26
0.40
FIGURE 5 J–V characteristics of the PFO-3ThPz-Tpa-based
Polymer:PC60BM ¼ 1:3 (w/w) under the illumination of AM 1.5, 100
BHJ-PSC with
a
structure of ITO/PEDOT:PSS/PFO-3ThPz-
mW/cm2.
b
Tpa:PC71BM(1:3, w/w)/LiF/Al under the illumination of AM 1.5
G from a solar simulator (100 mW cmꢂ2).
Polymer:PC71BM ¼ 1:3 (w/w) under the illumination of AM 1.5, 100
mW/cm2.
6
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 000, 000–000

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
and a standard three-electrode configuration under an argon
atmosphere at RT and a scan rate of 50 mV sꢂ1. Platinum
rod, platinum wire, and SCE were used as working electrode,
counter electrode, and reference electrode in a 0.1 mol Lꢂ1
tetrabutylammonium hexafluorophosphate (Bu4NPF6) aceto-
nitrile solution, respectively. Polymeric thin films on plati-
num rod were prepared by dipping the electrode into a 0.2–
1.0 wt % chloroform solution and dried under a nitrogen
steam before measurement.
14 mL). The mixture was degassed and vigorously stirred at
75ꢀC for 24 h under a nitrogen atmosphere. After cooled to
RT, the reaction mixture was extracted with DCM and water.
The organic layer was collected and dried over anhydrous
magnesium sulfate. The solvent was removed by rotary evap-
oration, and the residue was purified by column chromatog-
raphy (DCM/petroleum ether, 1/2, V/V) to give compound 2
as yellow liquid (1.43 g, 67.2%).
1H NMR (400 MHz, CDCl3, ppm): 8.11–8.09 (d, J ¼ 8.0 Hz,
4H), 7.82–7.80 (d, J ¼ 8.0 Hz, 4H), 7.79–7.77 (s, 2H), 7.74–
7.73 (d, J ¼ 6.2 Hz, 2H), 7.63–7.58 (t, 4H), 7.36–7.31 (m,
6H), 2.02–1.98 (t, 8H), 1.26–1.04 (m, 40H), 0.85–0.72 (m,
12H), 0.72–0.56 (t, 8H).
Polymer Solar Cell Fabrication and Test
The photovoltaic cells were constructed with a traditional
sandwich structure through the following steps. The ITO-
coated glass substrates were cleaned by a series of ultra-
sonic treatments for 10 min in acetone, following by deion-
ized water and then 2-propanol. The substrates were dried
under a nitrogen stream and subjected to the treatment of
Ar/O2 plasma for 5 min. A filtered aqueous solution of
poly(3,4-ethyl-enedioxy-thiophene)-poly(styrenesulfonate)
(PEDOT:PSS; Bayer AG) was spun-coat onto the ITO surface
at 2000 rpm for 30 s and then baked at 150ꢀC for 30 min to
form a PEDOT:PSS thin film with a thickness of 30 nm. A
blend of copolymer and PC60BM (1:3 w/w, 20 mg mLꢂ1 for
polymer) was dissolved in chlorobenzene, filtered through a
0.45-mm poly(tetrafluoroethylene) filter and spun-coat at
3000 rpm for 30 s onto the PEDOT:PSS layer. The substrates
were dried under N2 at RT and then annealed at 150ꢀC for
15 min in a nitrogen-filled glovebox. The devices were com-
pleted after thermal deposition of 10 nm lithium fluoride
and 0.5 nm aluminum as the cathode at a pressure of 6 ꢁ
10ꢂ4 Pa. The active area was 9 mm2 for each cell. The thick-
nesses of the spun-cast films were recorded by a profilome-
ter (Alpha-Step 200; Tencor Instruments).
Synthesis of 1,2-Bis(4-(9-octyl-9H-carbazol-3-yl)phenyl)
ethane-1,2-dione (4)
It was synthesized according to the synthetic procedure of
compound 2 and purified by column chromatography (DCM/
petroleum ether, 1/3, V/V) to give compound 4 as yellow
solid with a yield of 56.2%.
1H NMR (400 MHz, CDCl3, ppm): 8.38 (s, 2H), 8.16–8.01 (br,
6H), 7.89–7.87 (d, J ¼ 8.0 Hz, 4H), 7.78–7.76 (d, J ¼ 8.1 Hz,
2H), 7.50–7.48 (t, 4H), 7.44–7.42 (d, J ¼ 8.0 Hz, 2H), 7.28 (d,
2H), 4.35–4.31 (t, 4H), 1.91–1.88 (m, 4H), 1.40–1.25 (br,
20H), 0.86–0.84 (t, 6H).
Synthesis of Compound 6
It was synthesized according to the synthetic procedure of
compound 2 and purified by column chromatography (DCM/
petroleum ether, 1/3, V/V) to give compound 6 as red liquid
with a yield of 60.1%.
1H NMR (400 MHz, CDCl3, ppm): 8.01–7.99 (d, J ¼ 8.1 Hz,
4H), 7.68–7.66 (d, J ¼ 8.1 Hz, 4H), 7.45–7.43 (d, J ¼ 8.4 Hz,
4H), 7.09–7.07 (d, J ¼ 8.5 Hz, 8H), 6.97–6.95 (d, J ¼ 8.4 Hz,
4H), 6.85–6.83 (d, J ¼ 8.5 Hz, 8H), 3.95–3.92 (t, 8H), 1.79–
1.76 (m, 8H), 1.46–1.44 (m, 8H), 1.32–1.29 (br, 32H), 0.89–
0.87 (t, 12H).
Device characterization was carried out under an AM 1.5G
irradiation with an intensity of 100 mW cmꢂ2 (Oriel 91160,
300 W) calibrated by a NREL-certified standard silicon cell.
Current density–voltage (J–V) characteristics were measured
by a computer-controlled Keithley 2602 source measurement
unit in the dark. PCEs were detected under a monochromatic
illumination (Oriel Cornerstone 260 1/4 m monochromator
equipped with Oriel 70613NS QTH lamp), and the calibration
of the incident light was performed with a monocrystalline
silicon diode. All device characterizations were performed in
an ambient atmosphere at RT.
Synthesis of Monomer M2
5,500-Dibromo-30,40-dinitro-2,20:50200-terthiophene (1.49 g, 3.0
mmol), iron powder (2.18 g, 39 mmol), and acetic acid (60
mL) were mixed and heated at 60ꢀC for 30 min. The mixture
was cooled to RT and filtered in a 100 mL flask. Then, com-
pound 2 (4.0 mmol) was added to the flask. The mixture
was heated to 60ꢀC and stirred for 5 h under nitrogen
atmosphere. After cooled to RT, the mixture was mixed with
water (100 mL) to give precipitate. The precipitate was fil-
tered off and washed with water and CH3OH. Finally, the
washed precipitate was purified by column chromatography
(DCM/petroleum ether, 1/6, V/V) to give monomer M2 as
black-green solid (1.99 g, 47.8%).
Materials
All solvents and reagents, unless otherwise stated, were pur-
chased from commercial sources and used without further
purification. THF and toluene were dried over sodium/ben-
zophenone and distilled before use. Compounds 1,39 3,40 7,23
M1,41 and M5,22 were synthesized according to the
described procedures before.
Synthesis of 1,2-Bis(4-(9,9-dioctyl-9H-fluoren-2-
yl)phenyl)ethane-1,2-dione (2)
A mixture of compound 1 (2.48 g, 4.8 mmol), 1, 2-bis(4-bro-
mophenyl)ethane-1,2-dione (0.80 g, 2.17 mmol), and
Pd(PPh3)4 (0.14 g, 0.12 mmol) was added in a mixing solu-
tion of THF (42 mL) and aqueous potassium carbonate (2 M,
1H NMR (CDCl3, 400 MHz, ppm): 7.80–7.71 (br, 12H), 7.66–
7.64 (d, J ¼ 9.7 Hz, 4H), 7.35–7.33 (d, J ¼ 5.4 Hz, 8H), 7.08–
7.07 (d, J ¼ 3.7 Hz, 2H), 2.02–1.98 (t, 8H), 1.26–1.16 (br,
40H), 0.83–0.78 (m, 12H), 0.68–0.66 (t, 8H). 13C NMR
(CDCl3, 100 MHz, ppm): 152.9, 151.6, 151.1, 142.5, 141.0,
140.7, 139.0, 137.6, 136.1, 135.6, 130.7, 130.6, 129.9, 127.2,
WWW.MATERIALSVIEWS.COM
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 000, 000–000
7

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
126.9, 126.8, 126.1, 124.2, 124.0, 123.0, 121.4, 120.1, 119.9,
117.3, 114.7, 40.4, 31.8, 30.0, 29.2, 31.8, 30.0, 29.2, 23.8,
23.7, 22.6, 14.1. MALDI-TOF MS (m/z) for C84H94Br2N2S3,
Calcd: 1387.7; Found, 1388.4. ELEM. ANAL. for C84H94Br2N2S3,
Calcd: C, 72.70; H, 6.83; N, 2.02; S, 6.93. Found: C, 72.87; H,
6.97; N, 2.00; S, 6.92%.
for another 6 h. The final mixture was cooled to RT and
poured into methanol (150 mL) to form precipitate. The pre-
cipitate was collected and extracted with methanol, hexane,
acetone, and chloroform successively in Soxhlet apparatus
for 12 h each process. The collected chloroform solution was
concentrated to remove the great mass of chloroform and
the residual solution was dropped into methanol (150 mL)
to yield precipitate again. The precipitate was collected and
dried under vacuum over night to give PFO-3ThPz-Fl as
green solid (183 mg, 55.8%).
Synthesis of Monomer M3
It was synthesized according to the synthetic procedure of
monomer M2 and purified by column chromatography
(DCM/petroleum ether, 1/2, V/V) to give monomer M3 as
black solid with a yield of 45.5%.
1H NMR (CDCl3, 400 MHz, ppm): 7.94–7.60 (br, 24H), 7.52–
7.42 (br, 2H), 7.40–7.31 (br, 6H), 2.16–1.94 (t, 12H), 1.11–
0.69 (br, 90H). 13C NMR (CDCl3, 100 MHz, ppm): 152.6,
152.5, 151.9, 151.6, 151.2, 151.1, 145.8, 145.7, 142.4, 142.3,
141.0, 140.8, 140.7, 140.5, 139.1, 138.1, 138.0, 137.9, 134.3,
133.7, 133.3, 132.9, 130.7, 130.6, 130.4, 127.3, 127.2, 127.1,
126.9, 126.6, 126.3, 126.2, 126.1, 126.0, 125.3, 125.0, 124.8,
124.4, 123.8, 123.7, 123.6, 123.0, 122.9, 122.3, 121.4, 121.3,
120.9, 120.3, 120.2, 120.0, 119.9, 119.8, 55.4, 55.3, 53.3,
40.4, 31.8, 31.7, 30.0, 29.7, 29.2, 29.2, 23.8, 22.6, 14.0. ELEM.
ANAL. for C115H140N2S3, Calcd: C, 83.89; H, 8.57; N, 1.70; S,
5.84. Found: C, 83.95; H, 8.91; N, 1.69; S, 5.97%.
1H NMR (CDCl3, 400 MHz, ppm): 8.41(s, 2H), 8.17–8.15 (d, J
¼ 7.6 Hz, 2H), 7.79–7.72 (br, 10H), 7.50–7.41 (br, 6H), 7.35–
7.34 (d, J ¼ 3.4 Hz, 2H), 7.24–7.22 (d, J ¼ 7.44 Hz, 2H),
7.08–7.07 (d, J ¼ 3.52 Hz, 2H), 4.34–4.31 (t, 4H), 1.91–1.88
(m, 4H), 1.40–1.34 (br, 20H), 0.87–0.85 (t, 6H). 13C NMR
(CDCl3, 100 MHz, ppm): 153.0, 152.8, 142.9, 141.0, 140.2,
137.5, 136.9, 136.7, 136.2, 131.2, 130.7, 129.8, 126.7, 125.8,
125.0, 123.9, 123.8, 123.5, 123.1, 120.5, 119.0, 118.9, 114.5,
109.0, 108.9, 43.2, 31.8, 29.4, 29.2, 29.0, 27.3, 22.6, 14.1.
MALDI-TOF MS (m/z) for C66H60Br2N4S3, Calcd: 1165.2;
Found, 1165.2. ELEM. ANAL. for C66H60Br2N4S3, Calcd: C,
68.03; H, 5.19; N, 4.81; S, 8.26. Found: C, 67.93; H, 5.62; N,
4.66; S, 8.34.
PFO-3ThPz-Cz
Ninety-five milligrams, dark-green solid, yield: 33.4%. 1H
NMR (CDCl3, 400 MHz, ppm): 8.50–8.36 (br, 2H), 8.26–8.09
(br, 2H), 7.94–7.56 (br, 18H), 7.52–7.33 (br, 10H), 4.40–4.16
(t, 4H), 2.16–1.98 (t, 4H), 1.97–1.78 (m, 4H), 1.47–0.96 (br,
44H), 0.94–0.58 (t, 12H). 13C NMR (CDCl3, 100 MHz, ppm):
152.7, 152.6, 151.9, 151.8, 142.8, 142.6, 141.0, 140.5, 140.2,
140.1, 138.1, 138.0, 137.2, 137.1, 134.4, 134.2, 133.3, 133.2,
131.3, 131.2, 131.0, 130.7, 130.6, 130.5, 128.8, 127.2, 126.8,
126.7, 125.9, 125.8, 125.7, 125.0, 124.9, 123.6, 123.5, 123.4,
123.1, 122.4, 120.6, 120.5, 120.4, 120.3, 120.2, 119.9, 119.0,
118.9, 118.8, 109.0, 108.9, 108.8, 55.3, 53.3, 43.3, 43.2, 40.5,
40.4, 31.8, 30.2, 30.1, 30.0, 29.4, 29.2, 29.0, 27.3, 23.9, 23.8,
22.6, 19.0, 14.0. ELEM. ANAL. for C97H106N4S3, Calcd: C, 81.81;
H, 7.50; N, 3.93; S, 6.75. Found: C, 81.95; H, 7.67; N, 3.90; S,
7.06%.
Synthesis of Monomer M4
It was synthesized according to the synthetic procedure of
monomer M2 and purified by column chromatography
(DCM/petroleum ether, 1/2, V/V) to give monomer M4 as
black-red solid with a yield of 35.7%.
1H NMR (CDCl3, 400 MHz, ppm): 7.67–7.65 (d, J ¼ 7.8 Hz,
4H), 7.57–7.55 (d, J ¼ 7.9 Hz, 4H), 7.47–7.45 (d, J ¼ 8.2 Hz,
4H), 7.32–7.31 (d, J ¼ 3.7 Hz, 4H), 7.08–7.06 (d, J ¼ 8.6 Hz,
8H), 6.99–6.97 (d, J ¼ 8.0 Hz, 4H), 6.84–6.82 (d, J ¼ 8.4 Hz,
8H), 3.95–3.92 (t, 8H), 1.79–1.74 (m, 8H), 1.45–1.29 (br,
40H), 0.89–0.87 (t, 12H). 13C NMR (CDCl3, 100 MHz, ppm):
156.1, 153.3, 152.4, 147.5, 146.6, 142.4, 141.8, 138.8, 136.8,
136.5, 136.2, 130.8, 130.6, 130.5, 130.0, 127.4, 127.0, 126.9,
126.7, 126.6, 126.4, 126.1, 126.0, 125.8, 125.0, 115.8, 115.4,
114.6, 68.4, 31.9, 29.7, 29.4, 29.3, 26.3, 26.1, 22.7, 14.1.
MALDI-TOF MS (m/z) for C94H104Br2N4O4S3, Calcd: 1609.9;
Found, 1610.4. ELEM. ANAL. for C94H104Br2N4O4S3, Calcd: C,
70.13; H, 6.51; N, 3.48; S, 5.98. Found: C, 69.83; H, 6.78; N,
3.37; S, 6.12%.
PFO-3ThPz-Tpa
Two hundred fourteen milligrams, dark-green solid, yield:
1
57.2%. H NMR (CDCl3, 400 MHz, ppm): 7.92–7.53 (br, 14H),
7.52–7.34 (br, 8H), 7.13–7.03 (br, 8H), 7.02–6.93 (br, 4H),
6.92–6.72(br, 8H), 4.02–3.82 (t, 8H), 2.16–1.87 (t, 4H), 1.85–
1.71 (br, 8H), 1.46–0.97 (br, 64H), 0.95–0.57 (br, 18H). 13C
NMR (CDCl3, 100 MHz, ppm): 155.7, 152.7, 152.6, 151.9,
151.8, 148.7, 145.7, 145.6, 145.5, 141.5, 141.4, 140.6, 140.5,
140.4, 138.1, 138.0, 137.2, 135.0, 134.7, 134.4, 134.3, 134.2,
134.1, 134.0, 133.3, 132.2, 131.9, 131.8, 131.7, 130.7, 130.6,
130.5, 127.4, 127.1, 126.9, 126.8, 126.7, 126.2, 126.0, 125.9,
125.0, 124.9, 124.8, 124.6, 124.5, 123.7, 123.6, 123.5, 120.7,
120.6, 120.5, 120.4, 120.3, 115.9, 115.4, 68.4, 55.4, 53.3,
31.8, 31.7, 30.1, 30.0, 29.7, 29.4, 29.3, 29.2, 29.1, 26.1, 22.6,
22.5, 14.0. ELEM. ANAL. for C125H150N4O4S3, Calcd: C, 80.34; H,
8.09; N, 3.00; S, 5.15. Found: C, 79.74; H, 8.48; N, 3.01; S,
5.48%.
General Procedures of Suzuki Polycondensation, taking
PFO-3ThPz-Fl for Example
Monomers M1 (129 mg, 0.2 mmol), M2 (278 mg, 0.2 mmol),
and toluene (10 mL) were added to a 25 mL double-necked
round-bottomed flask. The mixture was purged with nitro-
gen flow for 30 min to remove oxygen and mixed with
Pd(PPh3)4 (2%, 5 mg) and tetraethyl ammonium hydroxide
(0.9 mL, 20% by weight in H2O). The resulting mixture was
refluxed for 72 h under nitrogen atmosphere. After cooled to
RT, phenylboric acid (50 mg in 0.5 mL of toluene) was added
and the mixture was refluxed for 6 h. Then, bromobenzene
(0.5 mL) was injected and the mixture was allowed to reflux
8
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 000, 000–000

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
16 Zhou, E.; Cong, J.; Tajima, K.; Hashimoto, K. Chem. Mater.
2010, 22, 4890–4895.
PFO-3ThPz-Ph
Forty-one milligrams, green solid, yield: 23.6%. 1H NMR
(CDCl3, 400 MHz, ppm): 7.87–7.30 (m, 20H), 2.21–1.90 (br,
4H), 1.33–0.92 (br, 24H), 0.89–0.55 (t, 6H). 13C NMR (CDCl3,
100 MHz, ppm): 152.9, 151.9, 150.2, 146.0, 145.9, 143.6,
143.2, 140.5, 139.2, 139.1, 138.0, 134.1, 134.0, 133.3, 133.2,
130.1, 130.0, 129.1, 129.0, 128.9, 128.8, 128.1, 128.0, 127.2,
126.2, 126.1, 125.1, 125.0, 124.9, 124.7, 123.7, 123.6, 123.5,
120.2, 120.1, 120.0, 55.4, 55.3, 53.4, 40.5, 31.8, 31.7, 30.1,
30.0, 29.7, 29.2, 25.0, 23.9, 23.8, 22.6, 14.0. ELEM. ANAL. for
17 Hou, J.; Chen, H.-Y.; Zhang, S.; Chen, R. I.; Yang, Y.; Wu, Y.;
Li, G. J. Am. Chem. Soc. 2009, 131, 15586–15587.
18 Liang, Y.; Xu, Z.; Xia, J.; Tsai, S.-T.; Wu, Y.; Li, G.; Ray, C.;
Yu, L. Adv. Mater. 2010, 22, E135–E138.
19 Piliego, C.; Holcombe, T. W.; Douglas, J. D.; Woo, C. H.;
ꢀ
Beaujuge, P. M.; Frechet, J. M. J. J. Am. Chem. Soc. 2010, 132,
7595–7597.
20 Price, S. C.; Stuart, A. C.; Yang, L.; Zhou, H.; You, W. J. Am.
Chem. Soc. 2011, 133, 4625–4631.
C57H60N2S3, Calcd: C, 78.75; H, 6.96; N, 3.22; S, 11.07. Found:
21 He, Z.; Zhong, C.; Huang, X.; Wong, W.-Y.; Wu, H.; Chen, L.;
Su, S.; Cao, Y. Adv. Mater. 2011, 23, 4636–4643.
C, 78.66; H, 7.14; N, 3.04; S, 10.71%.
22 Zhou, E.; Cong, J.; Yamakawa, S.; Wei, Q.; Nakamura, M.;
Tajima, K.; Yang, C.; Hashimoto, K. Macromolecules 2010, 43,
2873–2879.
ACKNOWLEDGMENTS
The authors thank the financial supports from the National Natu-
ral Science Foundation of China (21172187, 50973093), the Spe-
cialized Research Fund and the New Teachers Fund for the
Doctoral Program of Higher Education (2009 4301110004), the
Innovation Group and Xiangtan Joint Project in Hunan Natural
Science Foundation (12JJ7002 and 12JJ8001), the Postgraduate
Science Foundation for Innovation in Hunan Province
(CX2011B263), and the Research Learning and Innovative
Experiment Plan of the Ministry of Education.
€
23 Mammo, W.; Admassie, S.; Gadisa, A.; Zhang, F.; Inganas,
O.; Andersson, M. R. Sol. Energy Mater. Sol. Cells 2007, 91,
1010–1018.
24 Zhang, F.; Perzon, E.; Wang, X.; Mammo, W.; Andersson,
€
M. R.; Inganas, O. Adv. Funct. Mater. 2005, 15, 745–750.
25 Wang, X.; Chen, S.; Sun, Y.; Zhang, M.; Li, Y.; Li, X.; Wang,
H. Polym. Chem. 2011, 2, 2872–2877.
26 Liu, J.; Choi, H.; Kim, J. Y.; Bailey, C.; Durstock, M.; Dai, L.
Adv. Mater. 2011, 24, 538–542.
27 Wen, S.; Pei, J.; Zhou, Y.; Li, P.; Xue, L.; Li, Y.; Xu, B.; Tian,
W. Macromolecules 2009, 42, 4977–4984.
REFERENCES AND NOTES
28 Duan, C.; Cai, W.; Zhong, C.; Li, Y.; Wang, X.; Huang, F.;
Cao, Y. J. Polym. Sci. Part A: Polym. Chem. 2011, 49,
4406–4415.
1 Berggren, M.; Nilsson, D.; Robinson, N. D. Nat. Mater. 2007,
6, 3–5.
2 Gunes, S.; Neugebauer, H.; Sariciftci, N. S. Chem. Rev. 2007,
107, 1324–1338.
¨
29 Hsu, S.-L.; Chen, C.-M.; Wei, K.-H. J. Polym. Sci. Part A:
Polym. Chem. 2010, 48, 5126–5134.
3 Chen, J.; Cao, Y. Acc. Chem. Res. 2009, 42, 1709–1718.
30 Cheng, Y.-J.; Hung, L.-C.; Cao, F.-Y.; Kao, W.-S.; Chang, C.-
Y.; Hsu, C.-S. J. Polym. Sci. Part A: Polym. Chem. 2011, 49,
1791–1801.
4 Helgesen, M.; Sondergaard, R.; Krebs, F. C. J. Mater. Chem.
2010, 20, 36–60.
31 Huo, L.; Tan, Z. a.; Wang, X.; Zhou, Y.; Han, M.; Li, Y.
J. Polym. Sci. Part A: Polym. Chem. 2008, 46, 4038–4049.
ꢀ
5 Thompson, B. C.; Frechet, J. M. J. Angew. Chem. Int. Ed.
Engl. 2008, 47, 58–77.
32 Cheng, Y.-J.; Yang, S.-H.; Hsu, C.-S. Chem. Rev. 2009, 109,
5868–5923.
6 Dennler, G.; Scharber, M. C.; Brabec, C. J. Adv. Mater. 2009,
21, 1323–1338.
33 Yang, R.; Tian, R.; Yan, J.; Zhang, Y.; Yang, J.; Hou, Q.;
Yang, W.; Zhang, C.; Cao, Y. Macromolecules 2004, 38,
244–253.
7 Zhang, Y.; Zou, J.; Yip, H.-L.; Chen, K.-S.; Davies, J. A.; Sun,
Y.; Jen, A. K. Y. Macromolecules 2011, 44, 4752–4758.
8 Jung, I. H.; Kim, H.; Park, M.-J.; Kim, B.; Park, J.-H.; Jeong,
E.; Woo, H. Y.; Yoo, S.; Shim, H.-K. J. Polym. Sci. Part A:
Polym. Chem. 2010, 48, 1423–1432.
34 Yang, J.; Jiang, C.; Zhang, Y.; Yang, R.; Yang, W.; Hou, Q.;
Cao, Y. Macromolecules 2004, 37, 1211–1218.
35 Liu, M.; Wang, Y.; Zhang, Z.; Li, J.; Liu, Y.; Tan, H.; Ni, M.;
Lei, G.; Zhu, M.; Zhu, W. J. Polym. Sci. Part A: Polym. Chem.
2011, 49, 3874–3881.
9 Chen, G.-Y.; Cheng, Y.-H.; Chou, Y.-J.; Su, M.-S.; Chen, C.-M.;
Wei, K.-H. Chem. Commun. 2011, 47, 5064–5066.
10 Lee, S. K.; Kang, I.-N.; Lee, J.-C.; Shin, W. S.; So, W.-W.;
Moon, S.-J. J. Polym. Sci. Part A: Polym. Chem. 2011, 49,
3129–3137.
36 Wang, E.; Li, C.; Zhuang, W.; Peng, J.; Cao, Y. J. Mater.
Chem. 2008, 18, 797–801.
37 Yang, Y.-L.; Lee, Y.-H.; Chang, C.-J.; Lu, A.-J.; Hsu, W.-C.;
Wang, L.; Leung, M.-K.; Dai, C.-A. J. Polym. Sci. Part A: Polym.
Chem. 2010, 48, 1607–1616.
11 Lee, P.-I.; Lien-Chung Hsu, S.; Lee, J. F.; Chuang, H.-Y.; Lin,
P. J. Polym. Sci. Part A: Polym. Chem. 2011, 49, 662–670.
12 Nie, Y.; Zhao, B.; Tang, P.; Jiang, P.; Tian, Z.; Shen, P.; Tan,
S. J. Polym. Sci. Part A: Polym. Chem. 2011, 49, 3604–3614.
38 Kim, Y.; Cook, S.; Tuladhar, S. M.; Choulis, S. A.; Nelson, J.;
Durrant, J. R.; Bradley, D. D. C.; Giles, M.; McCulloch, I.; Ha, C.-
S.; Ree, M. Nat. Mater. 2006, 5, 197–203.
13 Song, J.; Du, C.; Li, C.; Bo, Z. J. Polym. Sci. Part A: Polym.
Chem. 2011, 49, 4267–4274.
39 Wang, Y.; Tan, H.; Liu, Y.; Jiang, C.; Hu, Z.; Zhu, M.; Wang,
L.; Zhu, W.; Cao, Y. Tetrahedron 2010, 66, 1483–1488.
14 Soci, C.; Hwang, I. W.; Moses, D.; Zhu, Z.; Waller, D.; Gaudi-
ana, R.; Brabec, C. J.; Heeger, A. J. Adv. Funct. Mater. 2007, 17,
632–636.
40 Paliulis, O.; Ostrauskaite, J.; Gaidelis, V.; Jankauskas, V.;
Strohriegl, P. Macromol. Chem. Phys. 2003, 204, 1706–1712.
15 Blouin, N.; Michaud, A.; Gendron, D.; Wakim, S.; Blair, E.;
Neagu-Plesu, R.; Belleteˆte, M.; Durocher, G.; Tao, Y.; Leclerc,
M. J. Am. Chem. Soc. 2007, 130, 732–742.
41 Dudek, S. P.; Pouderoijen, M.; Abbel, R.; Schenning, A. P. H.
J.; Meijer, E. W. J. Am. Chem. Soc. 2005, 127, 11763–11768.
WWW.MATERIALSVIEWS.COM
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 000, 000–000
9