Synthesis of fluorene-based hyperbranched polymers for solution-processable blue, green, red, and white light-emitting devices

Article abstract of DOI:10.1002/pola.25080

For the purpose of making hyperbranched polymer (Hb-Ps)-based red, green, blue, and white polymer light-emitting diodes (PLEDs), three Hb-Ps Hb-terfluorene (Hb-TF), Hb-4,7-bis(9,9′-dioctylfluoren-2-yl)-2,1,3- benzothiodiazole (Hb-BFBT), and Hb-4,7-bis[(9,9′-dioctylfluoren-2-yl)- thien-2-yl]-2,1,3-benzothiodiazole (Hb-BFTBT) were synthesized via [2+2+2] polycyclotrimerization of the corresponding diacetylene-functionalized monomers. All the synthesized polymers showed excellent thermal stability with degradation temperature higher than 355 °C and glass transition temperatures higher than 50 °C. Photoluminance (PL) and electroluminance (EL) spectra of the polymers indicate that Hb-TF, Hb-BFBT, and Hb-BFTBT are blue-green, green, and red emitting materials. Maximum brightness of the double-layer devices of Hb-TF, Hb-BFBT, and Hb-BFTBT with the device configuration of indium tin oxide/poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate)/light-emitting polymer/CsF/Al are 48, 42, and 29 cd/m²; the maximum luminance efficiency of the devices are 0.01, 0.02, and 0.01 cd/A. By using host-guest doped system, saturated red electrophosphorescent devices with a maximum luminance efficiency of 1.61 cd/A were obtained when Hb-TF was used as a host material doped with Os(fptz)₂(PPh₂Me₂) ₂ as a guest material. A maximum luminance efficiency of 3.39 cd/A of a red polymer light-emitting device was also reached when Hb-BFTBT was used as the guest in the PFO (Poly(9,9-dioctylfluorene)) host layer. In addition, a series of efficient white devices were, which show low turn-on voltage (3.5 V) with highest luminance efficiency of 4.98 cd/A, maximum brightness of 1185 cd/m², and the Commission Internationale de l'Eclairage (CIE) coordinates close to ideal white emission (0.33, 0.33), were prepared by using BFBT as auxiliary dopant.

Full text of DOI:10.1002/pola.25080

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Synthesis of Fluorene-based Hyperbranched Polymers for Solution-
Processable Blue, Green, Red, and White Light-Emitting Devices
Hung-Min Shih, Ren-Chi Wu, Ping-I Shih, Chien-Lung Wang, Chain-Shu Hsu
Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan, Republic of China
Correspondence to: C.-S. Hsu (E-mail: cshsu@mail.nctu.edu.tw)
Received 16 September 2011; accepted 20 October 2011; published online 19 November 2011
DOI: 10.1002/pola.25080
ABSTRACT: For the purpose of making hyperbranched polymer
(Hb-Ps)-based red, green, blue, and white polymer light-emit-
ting diodes (PLEDs), three Hb-Ps Hb-terfluorene (Hb-TF), Hb-
0.01 cd/A. By using host–guest doped system, saturated red
electrophosphorescent devices with a maximum luminance ef-
ficiency of 1.61 cd/A were obtained when Hb-TF was used as a
host material doped with Os(fptz)2(PPh2Me2)2 as a guest mate-
rial. A maximum luminance efficiency of 3.39 cd/A of a red
polymer light-emitting device was also reached when Hb-
BFTBT was used as the guest in the PFO (Poly(9,9-dioctylfluor-
ene)) host layer. In addition, a series of efficient white devices
were, which show low turn-on voltage (3.5 V) with highest
luminance efficiency of 4.98 cd/A, maximum brightness of 1185
cd/m2, and the Commission Internationale de l’Eclairage (CIE)
4,7-bis(9,90-dioctylfluoren-2-yl)-2,1,3-benzothiodiazole
(Hb-
BFBT), and Hb-4,7-bis[(9,90-dioctylfluoren-2-yl)-thien-2-yl]-2,1,3-
benzothiodiazole (Hb-BFTBT) were synthesized via [2þ2þ2] pol-
ycyclotrimerization of the corresponding diacetylene-function-
alized monomers. All the synthesized polymers showed
excellent thermal stability with degradation temperature higher
than 355 ꢀC and glass transition temperatures higher than 50
ꢀC. Photoluminance (PL) and electroluminance (EL) spectra of
the polymers indicate that Hb-TF, Hb-BFBT, and Hb-BFTBT are
blue-green, green, and red emitting materials. Maximum
brightness of the double-layer devices of Hb-TF, Hb-BFBT, and
Hb-BFTBT with the device configuration of indium tin oxide/
poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate)/light-
emitting polymer/CsF/Al are 48, 42, and 29 cd/m2; the maxi-
mum luminance efficiency of the devices are 0.01, 0.02, and
coordinates close to ideal white emission (0.33, 0.33), were pre-
C
V
pared by using BFBT as auxiliary dopant. 2011 Wiley Periodicals,
Inc. J Polym Sci Part A: Polym Chem 50: 696–710, 2012
KEYWORDS: electrophosphorescent devices; host materials;
hyperbranched polymers; polymer light-emitting diodes;
polyfluorene
INTRODUCTION Polymer light-emitting diodes (PLEDs) have
been attracting great interest because of their potential
applications in full-color flat panel displays and in solid-state
lighting.1–3 Display and lighting applications require the de-
velopment of highly efficient red, green, and blue light-emit-
ting materials with high stability and purity.4 Polyfluorene
(PF) is the most promising blue-light emitter for PLED appli-
cation because of its high photoluminescence (PL) quantum
efficiency and good chemical and thermal stability.5–9 To be
used in full-color displays and lighting applications, the emis-
sion spectra of PF-based polymers have been turned to cover
the entire visible region by incorporating electron-deficient
monomer into the PF backbone or by physically doping with
fluorescent and phosphorescent dyes with green or red
emission.10–12 Several electron-deficient monomers have
been reported as the comonomers to be incorporated into
the polymer backbone of wide band gap polymers. For exam-
ple, Jen and coworkers10 demonstrated efficient green emit-
ting polymers synthesized from copolymerization of fluorene
with an electron-deficient monomer, 2,1,3-benzothiadiazole
(BT). Recently, Cao and coworkers11 report a series of fluo-
rene and 4,7-dithienyl-BT (DTBT) copolymers.11 Devices
based on the copolymers emitted a saturated red light, with
kmax ranging from 628 to 674 nm. In these cases, the narrow
band gap unit functioned as an exciton trap, which allowed
intramolecular energy transfer from the fluorene segment to
the BT or DTBT units; exciton emission was centered on the
BT and DTBT units and resulted in green and red emission.
Based on the concept, Shu et al. developed a series of single
white light-emitting copolymers, which contain fluorene, BT,
and red DTBT moieties in their polymer backbones. By con-
trolling the feed ratio of BT and DTBT, the resulting copoly-
mers emit white light, with contributions from all three pri-
mary colors.12 Although the studies demonstrated the
success in modifying emission colors of PF-based polymers,
the control of color stability among different batches of the
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polymers is relatively difficult, because the emission colors
of these polymers are also dependent on the molecular
weights (Mw) and the actual molar ratio of the electron-defi-
cient moieties in the polymers, which is not readily
controllable.
host and a red-emitting osmium complex as a guest in the
emitting layer, which demonstrate the potential of Hb-TF as
a host material.43 The device efficiency of the red emitter,
Hb-BFTBT, was further improved in a host–guest doped
system, where Hb-BFTBT was used as red-emitting guest
in the PFO host layer. Furthermore, by adding BFBT, as aux-
iliary dopant in the PFO:Hb-BFTBT blend, white PLEDs
with Commission Internationale de l’Eclairage (CIE) coordi-
nates (0.33, 0.37), which are close to that of ideal white
light (0.33,0.33), low turn-on voltage (3.5 V) with highest
luminance efficiency of 4.98 cd/A, and maximum brightness
of 1185 cd/m2 were also achieved.44–46
In these regards, monodisperse luminescent oligomers char-
acterized with well-defined molecular structures and Mws
are developed.13 For example, Wong et al. demonstrated a
series of terfluorene (TF) and oligofluorene oligomers that
show bipolar transport properties with kmax of PL at around
427 nm. These oligomers are used as efficient blue emitters
and good host materials in the highly bright-blue organic
light-emitting diodes (OLEDs) devices.14–16 Wong et al. also
synthesized a highly efficient green emitter (PL, kmax: 544
nm) by incorporating the BT units into the oligoflourenes.
The resulting molecules exhibit excellent solid-state PL quan-
tum yields.17 Chen and coworkers18 further incorporated
various electron-deficient segments into molecular structure
of oligofluorenes to obtain a series of green and red emitting
oligomers.
EXPERIMENTAL
Materials
Tetrahydrofuran (THF) was distilled over sodium under
nitrogen. Toluene was dried over calcium hydride and then
distilled under nitrogen. Triethylamine (Et3N) was dried over
potassium hydroxide and then distilled under nitrogen. All
other solvents and reagents were purchased from commer-
cial sources and used without further purification. Com-
pounds 1, 2, 6, 10, and 13 were prepared according to
reported procedures.47 Os(fptz)2(PPh2Me2)2 (fptz ¼ 3-tri-
fluoromethyl-5-pyridyl-1,2,4-triazole) was prepared accord-
ing to reported procedures.48
Hyperbranched polymers (Hb-Ps) have been widely studied
in the past decades because of their unique molecular archi-
tectures and specific properties.19–27 Because of their unique
architectures, Hb-Ps have been widely reported as chemical
sensors, drug delivery carriers, molecular antennae, and immu-
nodiagnostic probes.28–34 Recently, Tang and coworkers35–37
developed a facial approach to synthesize conjugated Hb-poly-
arylenes (Hb-PAs) through the diyne [2þ2þ2] polycyclotrime-
rizations, catalyzed by transition metal complexes. Their Hb-
PAs are spin coated through solution processing and show
excellent optical properties, such as high light-emitting effi-
ciency and superb optical-limiting performance.38–42
9,9,90,90,900,900-Hexaoctylterfluorene (3)
Compounds 1 (2.53 g, 4.90 mmol) and 2 (5.0 g, 9.80 mmol)
were mixed with Pd(PPh3)4 (0.011 g, 9.8 lmol), Aliquat 336
(0.6 g, 1.25 mmol), and aqueous K2CO3 (2 M, 17 mL) in
degassed toluene (60 mL). The reaction mixture was stirred at
ꢀ
110 C under nitrogen for 24 h. After cooling to room temper-
ature, the solution was poured into 50 mL of water and
extracted with ethyl acetate. The combined organic layers were
dried over anhydrous MgSO4, and the solvent was removed
under reduced pressure. The crude product was purified by
column chromatography (silica gel, hexane was used as eluent)
To combine the advantageous color stability and purity of
oligomeric light-emitting molecules, and the convenience and
low cost of the solution processes, in this article, we devel-
oped a facile approach to synthesize blue, green, and red
emitting Hb-Ps, that is, Hb-TF, Hb-4,7-bis(9,90-dioctylfluoren-
2-yl)-2,1,3-benzothiodiazole (BFBT), and Hb-4,7-bis[(9,90-dio-
ctylfluoren-2-yl)-thien-2-yl]-2,1,3-benzothiodiazole (BFTBT)
through the [2þ2þ2] polycyclotrimerization (Scheme 4). As
illustrated in Scheme 4, we first synthesized TF, BFBT, and
BFTBT as the blue, green, and red chromophores and modi-
fied them into diyne-functionalized monomers, M1, M2, and
M3. [2þ2þ2] polycyclotrimerization was then introduced
to convert the acetylene groups of the monomers into ben-
zene rings, which act as the branching points in the result-
ing Hb-Ps. As the branch points limit the extension of the
conjugation length of the repeating units, the concept
retains the advantage of color stability of oligomeric ana-
logs and enable solution processability of the resulting
materials. The PL and electroluminance (EL) spectra show
that Hb-TF, Hb-BFBT, and Hb-BFTBT are solution-process-
able blue, green, and red emitters. Hb-TF was further used
as host material because of its large Eg. Red electrophos-
phorescent devices were fabricated by using Hb-TF as a
ꢀ
to yield 5.0 g (92%) white crystals, mp: 53 C.
1H NMR (CDCl3): d ¼ 0.72–0.85 (m, 18H, A(CH2)7ACH3),
0.98–1.11 (m, 72H, A(CH2)A(CH2)6ACH3), 2.00–2.01 (m,
12H, (CH2) A(CH2)6ACH3), 7.25–7.35 (m, six aromatic pro-
tons), 7.72–7.90 (m, 14 aromatic protons). 13C NMR (CDCl3):
d ¼ 152.01, 151.70, 151.24, 141.03, 140.72, 127.02, 126.35,
123.18, 121.72, 120.17, 55.40, 40.60, 32.01, 30.26, 26.42,
24.04, 22.82, 14.29. MS (FAB, observed m/z): 1168.
7,70-Dibromo-9,9,90,90,900,900-hexaoctylterfluorene (4)
A solution of compound 3 (7.5 g, 6.43 mmol) and FeCl3
(0.036 g, 0.22 mmol) in CHCl3 (60 mL) was stirred at room
temperature. Bromine (2.24 g, 14.15 mmol) in CHCl3
(10 mL) was added slowly. The reaction mixture was stirred
at room temperature for 12 h and then poured into sodium
thiosulfate solution (30 mL) until the red color of bromine
disappeared. The solution was extracted with ethyl acetate.
The combined organic layers were dried over anhydrous
MgSO4, and the solvent was removed under reduced pressure.
The crude product was purified by column chromatography
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(silica gel, hexane was used as eluent) to yield 7.2 g (85%)
white solid, mp: 50 C.
14 mL) in degassed toluene (40 mL). The reaction mixture
was stirred at 110 C under nitrogen for 24 h. After cooling
ꢀ
ꢀ
to room temperature, the solution was poured into 50 mL of
water and extracted with ethyl acetate. The combined or-
ganic layers were dried over anhydrous MgSO4, and the sol-
vent was removed under reduced pressure. The crude prod-
uct was purified by column chromatography (silica gel, ethyl
acetate/hexane ¼ 1/50 was used as eluent) to yield 3.0 g
(96%) yellow oil.
1H NMR (CDCl3): d ¼ 0.72–0.85 (m, 18H, A(CH2)7ACH3),
0.98–1.11 (m, 72H, A(CH2)A(CH2)6ACH3), 2.00–2.01 (m,
12H, (CH2)A(CH2)6ACH3), 7.33–7.35 (m, two aromatic pro-
tons), 7.49 (d, two aromatic protons), 7.58–7.66 (m, 10 aro-
matic protons), 7.73–7.83 (m, 4 aromatic protons). 13C NMR
(CDCl3): d ¼ 153.47, 151.99, 151.70, 151.22, 141.01, 140.69,
140.53, 139.43, 127.20, 127.00, 126.38, 126.25, 123.16,
121.62, 121.30, 120.01, 119.94, 55.40, 40.60, 32.01, 30.26,
26.42, 24.04, 22.82, 14.29. MS (FAB, observed m/z): 1322.
1H NMR (CDCl3): d ¼ 0.72 (m, 12H, A(CH2)7ACH3), 0.98–
1.11 (m, 48H, A(CH2)A(CH2)6ACH3), 2.00–2.05 (m, 8H,
(CH2)A(CH2)6ACH3), 7.31–7.41 (m, six aromatic protons),
7.76–8.05 (m, 10 aromatic protons). 13C NMR (CDCl3): d ¼
154.58, 151.54, 151.35, 141.55, 140.88, 136.40, 133.82,
128.36, 128.12, 127.48, 127.06, 124.10, 123.18, 120.17,
119.92, 55.40, 40.60, 32.01, 30.26, 26.42, 24.04, 22.82,
14.29. MS (FAB, observed m/z): 913.
7,70-Bis(trimethylsilylethynyl)-9,9,90,90,900,900-
hexaoctylterfluorene (5)
A mixture of compound 4 (7.0 g, 5.29 mmol), PdCl2(PPh3)2
(0.075 g, 0.11 mmol), CuI (0.08 g, 0.42 mmol), and PPh3
(0.11 g, 0.42 mmol) in Et3N (150 mL) was stirred at 85 ꢀC
under nitrogen. Trimethylsilyl acetylene (2.1 g, 21.18 mmol)
was added slowly. The reaction mixture was allowed to react
at 85 ꢀC under nitrogen for 12 h. After cooling to room tem-
perature, the solution was poured into NH4Cl aqueous solution
and extracted with ethyl acetate. The combined organic layers
were dried over anhydrous MgSO4, and the solvent was
removed under reduced pressure. The crude product was puri-
fied by column chromatography (silica gel, hexane was used as
4,7-Bis(7-bromo-9,90-dioctylfluoren-2-yl)-2,1,3-
benzothiodiazole (8)
A solution of compound 7 (3.4 g, 3.72 mmol) and FeCl3
(0.030 g, 0.19 mmol) in CHCl3 (40 mL) was stirred at room
temperature. Bromine (1.3 g, 8.22 mmol) in CHCl3 (10 mL)
was added slowly. The reaction mixture was stirred at room
temperature for 12 h and then poured into sodium thiosulfate
solution (20 mL) until the red color of bromine disappeared.
The solution was extracted with ethyl acetate. The combined
organic layers were dried over anhydrous MgSO4, and the sol-
vent was removed under reduced pressure. The crude prod-
uct was purified by recrystallization from THF/MeOH (v/v ¼
ꢀ
eluent) to yield 3.0 g (42%) white crystals, mp: 42 C.
1H NMR (CDCl3): d ¼ 0.305 (s, 18H, ACH3), 0.68–0.85 (m, 18H,
A(CH2)7ACH3), 1.08–1.19 (m, 72H, A(CH2)A(CH2)6ACH3),
2.00–2.06 (m, 12H, (CH2)A(CH2)6ACH3), 7.47–7.50 (m, four
aromatic protons), 7.61–7.68 (m, 10 aromatic protons),
7.75–7.83 (m, four aromatic protons). 13C NMR (CDCl3): d ¼
152.04, 151.12, 141.22, 140.56, 139.80, 126.42, 121.60,
120.51, 106.52, 55.40, 40.60, 32.01, 30.26, 26.42, 24.04,
22.82, 14.29. MS (FAB, observed m/z): 1359.
ꢀ
1/3) to yield 2.9 g (73%) green crystals, mp: 40 C.
1H NMR (CDCl3): d ¼ 0.72 (m, 12H, A(CH2)7ACH3), 0.98–
1.11 (m, 48H, A(CH2)A(CH2)6ACH3), 2.00–2.05 (m, 8H,
(CH2)A(CH2)6ACH3), 7.47–7.51 (d, four aromatic protons),
7.61–7.65 (d, two aromatic protons), 7.82–8.04 (m, eight
aromatic protons). 13C NMR (CDCl3): d ¼ 154.51, 153.77,
151.36, 140.85, 140.48, 139.89, 136.83, 136.33, 134.02,
133.75, 130.31, 128.57, 128.20, 126.50, 124.15, 123.20,
121.53, 120.05, 55.40, 40.60, 32.01, 30.26, 26.42, 24.04,
22.82, 14.29. MS (FAB, observed m/z): 1071.
7,70-Diethynyl-9,9,90,90,900,900-hexaoctylterfluorene (M1)
A mixture of compound 5 (1.5 g, 5.42 mmol) and K2CO3
(0.5 g, 27.08 mmol) in MeOH/THF (6 mL, v/v ¼ 1/3) was
stirred at room temperature for 12 h. After cooling to room
temperature, the solution was poured into 50 mL of water
and extracted with ethyl acetate. The combined organic
layers were dried over anhydrous MgSO4, and the solvent
was removed under reduced pressure. The crude product
was purified by column chromatography (silica gel, hexane
was used as eluent) to yield 1.1 g (82%) yellow oil.
4,7-Bis(7-(3-hydroxy-3-methylbut-1-ynyl)-9,90-
dioctylfluoren-2-yl)-2,1,3-benzothiodiazole (9)
A mixture of compound 8 (2.4 g, 2.24 mmol), PdCl2(PPh3)2
(0.22 g, 0.31 mmol), CuI (0.051 g, 0.27 mmol), and PPh3
(0.12 g, 0.46 mmol) in Et3N (50 mL) was stirred at 85 ꢀC
under nitrogen. 2-Methylbut-3-yn-2-ol (1.13 g, 13.43 mmol)
was added ꢀslowly. The resulting solution was allowed to
react at 85 C under nitrogen for 12 h. After cooling to room
temperature, the solution was poured into 50 mL of NH4Cl
aqueous solution and extracted with ethyl acetate. The com-
bined organic layers were dried over anhydrous MgSO4, and
the solvent was removed under reduced pressure. The crude
product was purified by column chromatography (silica gel,
ethyl acetate/hexane ¼ 1/5 was used as eluent) to yield
1H NMR (CDCl3): d ¼ 0.68–0.85 (m, 18H, A(CH2)7ACH3),
1.08–1.19 (m, 72H, A(CH2)A(CH2)6ACH3), 2.00–2.06 (m,
12H, (CH2)A(CH2)6ACH3), 3.17 (s, 2H, BCAH), 7.51–7.54
(m, four aromatic protons), 7.64–7.70 (m, 10 aromatic pro-
tons), 7.78–7.85 (m, four aromatic protons). 13C NMR
(CDCl3): d ¼ 152.06, 151.12, 141.22, 140.56, 139.80, 126.42,
121.60, 120.51, 106.52, 84.5, 55.40, 40.60, 32.01, 30.26,
26.42, 24.04, 22.82, 14.29. MS (FAB, observed m/z): 1214.
4,7-Bis(9,90-dioctylfluoren-2-yl)-2,1,3-benzothiodiazole (7)
Compounds 6 (1.00 g, 3.40 mmol) and 2 (3.86 g, 7.48
mmol) were mixed with Pd(PPh3)4 (0.008 g, 0.0034 mmol),
Aliquat 336 (0.22 g, 0.85 mmol), and aqueous K2CO3 (2 M,
ꢀ
2.21 g (91%) yellow crystals, mp: 70 C.
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1H NMR (CDCl3): d ¼ 0.72 (m, 12H, A(CH2)7ACH3), 0.98–1.11
(m, 48H, A(CH2)A(CH2)6ACH3), 1.67 (s, 12H, ACA(OH)A
(CH3)2), 2.00–2.05 (m, 10H, (CH2) A(CH2)6ACH3AOH), 7.43–
7.46 (d, four aromatic protons), 7.69–7.72 (d, two aromatic
protons), 7.83–7.87 (d, two aromatic protons), 7.88 (s, two
aromatic protons), 7.94 (s, two aromatic protons), 8.02–8.04
(d, two aromatic protons). 13C NMR (CDCl3): d ¼ 154.52,
151.56, 141.14, 140.82, 136.84, 133.75, 131.00, 128.52, 128.16,
126.35, 124.12, 121.36, 120.25, 120.04, 94.00, 83.36, 66.02,
55.40, 40.60, 32.01, 30.26, 26.42, 24.04, 22.82, 14.29. MS (FAB,
observed m/z): 1077.
2-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-7-
(triisopropylsilylethynyl)-9,90-dioctylfluorene (12)
n-Butyllithium (5.4 mL, 10.64 mmol, 2.5 M solution in hex-
ane) was added into a solution of compound 11 (3.5 g, 5.9
mmol) in anhydrous THF (100 mL), which was cooled to
ꢁ78 ꢀC, and the obtained solution was stirred for 2 h, and
then
2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane
(3.8 mL, 14.75 mmol) was added slowly. The reaction mix-
ture was warmed up slowly to room temperature and then
stirred for 12 h. The mixture was quenched with water and
extracted with ethyl acetate. The combined organic layers
were dried over anhydrous MgSO4, and the solvent was
removed under reduced pressure. The crude product was
purified by column chromatography (silica gel, hexane was
4,7-Bis(7-ethynyl-9,90-dioctylfluoren-2-yl)-2,1,3-
benzothiodiazole (M2)
ꢀ
used as eluent) to yield 2.7 g (52%) white solid, mp: 25 C.
A mixture of KOH (2.08 g, 27.08 mmol) and compoundꢀ9
(2.0 g, 5.42 mmol) in toluene (40 mL) was stirred at 110 C
under nitrogen for 12 h. After cooling to room temperature,
the solution was poured into 50 mL of water and extracted
with ethyl acetate. The combined organic layers were dried
over anhydrous MgSO4, and the solvent was removed under
reduced pressure. The crude product was purified by column
chromatography (silica gel, ethyl acetate/hexane ¼ 1/6 was
used as eluent) to yield 1.8 g (95%) yellow oil.
1H NMR (CDCl3): d ¼ 0.72 (t, 6H, A(CH2)7ACH3), 0.98–1.11
(m, 24H, A(CH2)A(CH2)6ACH3), 1.39 (s, 12H, ACH3), 1.98
(t, 4H, (CH2)A(CH2)6ACH3), 7.25–7.35 (m, three aromatic
protons), 7.70–7.80 (m, four aromatic protons). 13C NMR
(CDCl3): d ¼ 151.54, 150.09, 144.36, 141.14, 133.93, 129.05,
127.71, 126.88, 123.15, 120.31, 119.18, 83.92, 55.30, 40.49,
32.02, 30.23, 29.43, 25.17, 23.89, 22.82, 14.31. MS (EI,
observed m/z): 640.
1H NMR (CDCl3): d ¼ 0.72–0.90 (m, 12H, A(CH2)7ACH3),
0.98–1.11 (m, 48H, A(CH2)A(CH2)6ACH3), 2.00–2.05 (m, 8H,
(CH2)A(CH2)6ACH3AOH), 3.17 (s, 2H, : CAH), 7.51–7.54 (d,
four aromatic protons), 7.71–7.74 (d, two aromatic protons),
7.75–7.89 (m, four aromatic protons), 7.95 (s, two aromatic
protons), 8.02–8.03 (d, two aromatic protons). 13C NMR
(CDCl3): d ¼ 154.28, 151.33, 141.42, 140.46, 139.28, 136.75,
133.52, 131.26, 128.31, 127.95, 126.61, 123.92, 120.43,
120.12, 119.85, 114.06, 84.70, 55.40, 40.60, 32.01, 30.26,
26.42, 24.04, 22.82, 14.29. MS (FAB, observed m/z): 962.
4,7-Bis(5-(7-(triisopropylsilylethynyl)-9,90-dioctylfluoren-
2-yl)-thien-2-yl)-2,1,3-benzothiodiazole (14)
Compounds 13 (0.77 g, 1.70 mmol) and 12 (2.70 g, 4.20
mmol) were mixed with Pd2(dba)3 (0.05 g, 0.05 mmol), Ali-
quat 336 (0.16 g, 0.63 mmol), and aqueous Cs2CO3 (15 mL,
5.8 mmol, 0.4 M) in degassed toluene (40 mL). The reaction
ꢀ
mixture was stirred at 110 C under nitrogen for 24 h. After
cooling to room temperature, the solution was poured into
50 mL of water and extracted with ethyl acetate. The com-
bined organic layers were dried over anhydrous MgSO4, and
the solvent was removed under reduced pressure. The crude
product was purified by column chromatography (silica gel,
hexane was used as eluent) to yield 0.6 g (25%) red oil.
2-Bromo-7-(triisopropylsilylethynyl)-9,90-
dioctylfluorene (11)
A mixture of compound 10 (4.0 g, 7.43 mmol), PdCl2(PPh3)2
(0.52 g, 0.74 mmol), and CuI (0.028 g, 0.15 mmol) in piperi-
dine (50 mL) was stirred at 40 ꢀC under nitrogen. Ethynyl-
triisopropylsilane (1.50 g, 8.20 mmol) was added slowly. The
1H NMR (CDCl3): d ¼ 0.72 (t, 6H, A(CH2)7ACH3), 0.98–1.11
(m, 24H, A(CH2) A(CH2)6ACH3), 1.36 (s, 12H, ACH3), 1.98
(t, 4H, (CH2)A(CH2)6ACH3), 7.25–7.35 (m, three aromatic
protons), 7.60–7.82(m, four aromatic protons). MS (FAB,
observed m/z): 1324.
ꢀ
resulting solution was allowed to react at 40 C under nitro-
gen for 12 h. After cooling to room temperature, the solution
was poured into 50 mL of NH4Cl aqueous solution and
extracted with ethyl acetate. The combined organic layers were
dried over anhydrous MgSO4, and the solvent was removed
under reduced pressure. The crude product was purified by
column chromatography (silica gel, hexane was used as eluent)
to yield 3.50 g (92%) yellow crystals.
4,7-Bis(5-(7-diethynyl-9,9-dioctylfluoren-2-yl)-thien-2-yl)-
2,1,3-benzothiodiazole (M3)
Tetrabutylammonium fluoride (TBAF) (1.3 mL, 1.3 mmol,
1.0 M in THF) was added to a solution of compound 14
(0.60 g, 0.45 mmol) in anhydrous THF (20 mL) at room tem-
perature, and the reaction mixture was stirred at room tem-
perature for 1 h. The solution was poured into 50 mL of water
and extracted with ethyl acetate. The combined organic layers
were dried over anhydrous MgSO4, and the solvent was
removed under reduced pressure. The crude product was puri-
fied by column chromatography (silica gel, ethyl acetate/hex-
ane ¼ 1/6 was used as eluent) to give 0.45 g (90%) red oil.
1H NMR (CDCl3):
d
¼
0.80 (t,
J
¼
6.90 Hz, 6H,
A(CH2)7ACH3), 1.01–1.23 (m, 24H, A(CH2)A(CH2)6ACH3),
1.64 (s, 12H, AC(CH3)2AOH), 1.90 (t, 4H, A(CH2)A
(CH2)6ACH3), 2.11 (s, 2H, AC(CH3)2AOH), 7.37 (d, two aro-
matic protons), 7.51 (s, two aromatic protons), 7.57 (d, two
aromatic protons). 13C NMR (CDCl3): d ¼ 151.34, 141.02,
131.15, 126.43, 121.77, 120.22, 94.28, 83.42, 66.17, 55.58,
40.75, 40.72, 32.18, 31.96, 30.38, 29.63, 24.04, 22.99, 14.48.
MS (EI, observed m/z): 592.
1H NMR (CDCl3): d ¼ 0.67–0.90 (t, J ¼ 7.05 Hz, 6H,
A(CH2)7ACH3), 1.02–1.58 (m, 24H, A(CH2)A(CH2)6ACH3),
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2.03 (t, J ¼ 3.90 Hz, 4H, A(CH2)A(CH2)6ACH3), 3.17 (s,
2H, :CAH), 7.35 (d, four aromatic protons), 7.50 (d, J ¼
7.80 Hz, four aromatic protons), 7.66 (d, four aromatic pro-
tons), 7.72 (s, two aromatic protons), 7.95 (s, two aromatic
protons), 8.16 (d, two aromatic protons). 13C NMR (CDCl3):
d ¼ 150.62, 140.55, 130.81, 126.11, 120.40, 119.53, 84.09,
54.77, 39.79, 39.76, 31.32, 29.51, 29.49, 28.76, 23.21, 22.14,
13.62. MS (FAB, observed m/z): 1012.
solved in acetonitrile. The potentials were measured against
an Ag/AgCl reference electrode using ferrocene/ferrocenium
(Fc/Fcþ) as the internal standard.
Fabrication and Measurements of PLED
Two polymer light-emitting devices having the configuration
of indium tin oxide (ITO)/poly(3,4-ethylene dioxythiophene)
(PEDOT):poly(styrene sulfonate) (PEDOT:PSS) (40 nm)/light-
emitting polymer (60–80 nm)/CsF (2 nm)/Al (100 nm)
and ITO/PEDOT:PSS (40 nm)/light-emitting polymer (60–
80 nm)/TPBI (30 nm)/LiF (1 nm)/Al (100 nm) were fabri-
cated. The patterned ITO glass substrates were ultrasonically
cleaned with detergent, deionized water, acetone, and isopro-
pyl alcohol. The PEDOT:PSS (Baytron P VP AI4083 from H. C.
Stack) was spin coated on the cleaned and UV–ozone-treated
ITO substrates. The PEDOT:PSS layer was baked at 120 ꢀC
for 30 min in air to remove residual water and then moved
into a glove box under nitrogen. The light-emitting polymers
dissolved in chlorobenzene solution were spin coated on top
General Polymerization Procedure
The monomers were polymerized using TaCl5 as the catalyst.
All polymerization reactions and manipulations were carried
out under nitrogen using either an inert-atmosphere glove
box or Schlenk techniques in a vacuum line system. The pu-
rification of the polymers was done in a fume hood. A typical
experimental procedure for the polymerization of monomer
M1 is given below as an example (Scheme 4). Monomer 1
(0.6 g, 0.49 mmol) was added into a Schlenk tube with a
three-way stopcock on the sidearm. The tube was evacuated
under vacuum and then flushed with dried nitrogen three
times through sidearm. Dried toluene (5 mL) was injected
into the tube through a septum to dissolve the monomer. The
catalyst solution was prepared in another tube by dissolving
TaCl5 (42 mg, 0.118 mmol) in 11 mL of toluene. The mono-
mer solution was then transferred to the catalyst solution
using a hypodermic syringe. The resulting mixture was stirred
at room temperature under nitrogen for 8 h, and then metha-
nol was added to the solution. The mixture was added drop-
wise to methanol through a cotton filter with stirring. The
polymer precipitate was allowed to stand for 1 h and was
then separated by filtration, purified by several reprecipitation
steps from toluene solution into methanol, and then dried in
a vacuum oven to yield 0.52 g (86%) yellow solid Hb-TF.
ꢀ
of the PEDOT:PSS layer. Then, the films were baked at 80 C
for 30 min under vacuum. The TPBI (1,3,5-tris(1-phenyl-1H-
benzimidazol-2-ol)benzene) layer, which was grown through
thermal deposition, was used as an electron transporting
layer that would block holes and confine excitons. The devi-
ces were completed by thermal deposition of a CsF (2 nm)/
Al (100 nm) or LiF (1 nm)/Al (100 nm) as cathode. The cur-
rent–voltage–luminance characteristics were measured by
using an optical power meter PR-650 and a digital source
meter Keithley 2400. The EL spectra were measured by
using a Photo Research PR-650 spectrophotometer under
ambient condition after encapsulation.
RESULTS AND DISCUSSION
Characterization
Synthesis and Characterization of Monomers and
1H and 13C NMR spectra were recorded on a Varian-300
MHz spectrometer. Mass spectra were obtained using a JEOL
JMS-HX 110 mass spectrometer. Gel permeation chromatog-
raphy (GPC) was measured using a Viscotek GPC system
equipped with a Viscotek T50A differential viscometer and a
Viscotek LR125 laser referactometer. Three 10-lm columns
were connected in series in order of decreasing pore size
(105, 104, and 103 Å). Polystyrene standards were used for
calibration, and THF was used as the eluent. Thermogravi-
metric analysis (TGA) was carried out using a Perkin Elmer
Pyris 7 instrument. The thermal stabilities of the samples
under nitrogen were determined by measuring their weight
Polymers
Schemes 1–3 illustrate the synthetic routes of the monomers.
M1, M2, and M3 were synthesized based on the following
procedure. First, reacting 2,7-dibromo-9,9-dioctylfluorene (1)
and 2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-dio-
ctylfluorene (2) through Suzuki coupling reaction allows the
formation of compound 3. Compound 3 was then bromi-
nated with bromide and catalytic amount of Lewis acid,
FeCl3, to give compound 4. Reacting the bromo groups of
compound 4 with trimethylsilylacetylene by Sonogashira
coupling reaction yielded compound 5.49 Finally, M1 was
obtained by deprotecting the terminal acetylene groups of
compound 5 under basic condition with K2CO3. M2 was syn-
thesized based on the following procedure. Compound 7 was
also synthesized by reacting compounds 2 and 6 through
Suzuki coupling reaction. Compound 7 was then brominated
with bromide to give the corresponding compound 8,49
which was further reacted with 2-methyl-3-butyn-2-ol by
Sonogashira coupling reaction to yield compound 9. Depor-
tecting compound 9 under basic and high temperature con-
dition allows the formation of monomer M2. M3 was synthe-
sized based on the following procedure. Compound 14 was
synthesized by reacting compounds 12 and 13 through
Suzuki coupling reaction. Compound 14 was deprotect with
ꢀ
losses while heating at a rate of 10 C/min. Differential scan-
ning calorimetry (DSC) was performed on a Perkin Elmer
Pyris Diamond DSCꢀ unit operated at a heating and cooling
rates of 20 and 40 C/min, respectively. The glass transition
temperatures (Tgs) were determined from the second heat-
ing scan. UV–Vis spectra were measured using an HP 8453
spectrophotometer. PL spectra were obtained using an ARC
SpectraPro-150 luminance spectrometer. Cyclic voltammetry
(CV) experiments were performed using an Autolab ADC 164
electrochemical analyzer operated at a scanning rate of
50 mV/s; the supporting electrolyte was 0.1 M tetra-n-buty-
lammonium tetrafluoroborate (n-Bu4NBF4), which was dis-
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SCHEME 1 Synthetic route of M1. Reagents and conditions: (i) Pd(PPh3)4, K2CO3, Aliquat 336, toluene, H2O, reflux; (ii) FeCl3, Br2,
CHCl3, 0 ꢀC; (iii) trimethylsilylacetylene, PdCl2(PPh3)2, CuI, PPh3, Et3N, 85 ꢀC; (iv) K2CO3, MeOH/THF (1:3, v/v), r.t.
n-Bu4NF under basic condition to allow the formation of
monomer M3.
belongs to the aromatic H on the BT unit can be observed
for M2. For monomer M3, the double peaks at d 7.66 ppm
represent the protons in the thiophene rings of DTBT. Thus,
M1, M2, and M3 were characterized with 1H and 13C NMR
spectroscopy and FAB-MS (Supporting Information). In the
1H NMR spectra, the characteristic peak of AC:CAH at d
3.17 ppm was observed for all of the monomers, which indi-
cates the success of Sonogashira coupling reactions and the
deprotection reactions. Compared to the 1H NMR spectrum
of M1, a characteristic singlet peak at d 7.95 ppm that
1
the H NMR spectra differentiate the difference in the molec-
ular structures of the monomers. In the 13C NMR spectra,
the feature signal peak of the carbon on the terminated tri-
ple bond of the monomers was also observed at d 84.5 ppm.
In the mass spectra, the m/z values of 1214, 962, and 1012
were observed for M1, M2, and M3, which closely match
SCHEME 2 Synthetic route of M2. Reagents and conditions: (i) Pd(PPh3)4, K2CO3, Aliquat 336, toluene, H2O, reflux; (ii) FeCl3, Br2,
CHCl3, 0 ꢀC; (iii) 2-methyl-3-butyn-2-ol, PdCl2(PPh3)2, CuI, PPh3, Et3N, reflux; (iv) KOH, toluene, reflux.
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SCHEME 3 Synthetic route of M3. Reagents and conditions: (i) PdCl2(PPh3)2, ethynyltriisopropylsilane, CuI, piperidine, 40 ꢀC; (ii) n-BuLi,
2-isopropyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, THF, ꢁ78 ꢀC; (iii) Pd(PPh3)4, K2CO3, Aliquat 336, toluene, H2O, reflux; (iv) n-Bu4NF,
THF, r.t.
with the calculated monoisotopic masses of the monomers.
All the molecular characterization results clearly indicate the
success of the reactions and confirm the chemical identify of
M1, M2, and M3. The Hb-Ps, Hb-TF, Hb-BFBT, and Hb-
BFTBT were synthesized by using M1, M2, and M3 as
monomers via [2þ2þ2] polycyclotrimerization (Scheme 4).
The Hb-Ps compared with the monomers show much weaker
signal for the AC:CAH proton in their 1H NMR spectra
through the polycyclotrimerization reaction (Supporting In-
formation Fig. S1). Thus, the peak intensities of the
AC:CAH proton (d 3.17 ppm) decreased after the polymer-
ization reactions, and their remaining intensities depend on
the degree of polymerization. The molecular weights and pol-
ydispersity indices (PDI) of Hb-TF, Hb-BFBT, and Hb-BFTBT
were characterized with GPC and summarized in Table 1.
Hb-TF possesses much higher Mw (136.8 ꢂ 103 g/mol, PDI:
1.86) than those of Hb-BFBT (6.984 ꢂ 103 g/mol, PDI: 1.50)
and Hb-BFTBT (7.853
ꢂ
103 g/mol, PDI: 1.43). The
decomposition temperatures (Td) of Hb-TF, Hb-BFBT, and
Hb-BFTBT are 401, 355, and 400 ꢀC, which indicate good
thermal stability (Supporting Information). The polymers
Hb-TF, Hb-BFBT, and Hb-BFTBT reveal Tgs at 110, 51, and
89 ꢀC, respectively (Table 1 or Supporting Information Figs.
S13–S18). It is evidenced that all the Hb-Ps show good ther-
mal behaviors.
Optical Properties
To examine the photophysical properties of these polymers,
the absorption and PL spectra of dilute solutions and solid
films of Hb-TF, Hb-BFBT, and Hb-BFTBT were measured.
Figures 1–3 show the UV–Vis and PL spectra of the dilute
solutions and thin films of Hb-TF, Hb-BFBT, and Hb-BFTBT,
respectively. The spectral data are summarized in Table 2. In
the dilute solutions, Hb-TF shows only one absorption band
SCHEME 4 Synthesis of Hb-TF, Hb-BFBT, and Hb-BFTBT from M1, M2, and M3 by polycyclotrimerization reaction.
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TABLE 1 Number-Average Molecular Weights (Mn), Weight-
Average Molecular Weights (Mw), PDI, and Thermal Properties
of the Hyperbranched Polymers
a
a
b
c
Mn
Mw
PDIa
Td
Tg
Polymer
(ꢂ103)
(ꢂ103)
(Mw/Mn)
(ꢀC)
(ꢀC)
Hb-TF
Hb-BFBT
Hb-BFTBT
a
136.8
6.984
7.853
255.4
1.86
1.50
1.43
401
355
387
110
51
10.528
11.254
89
Weight-average molecular weights (Mw) and PDI of the polymers were
determined by GPC in THF using polystyrene standards.
b
The 5% weight loss of the decomposition temperature measured by
TGA under N2.
c
The glass transition temperature measured by DSC under N2.
FIGURE 2 UV–Vis absorption and PL spectra of Hb-BFBT in so-
with kmax at 365 nm, which is originated from the localized
p–p* transitions of the TF unit, while Hb-BFBT and Hb-
BFTBT show two distinct absorption bands (Table 2). The
shorter wavelength absorption bands of Hb-BFBT and Hb-
BFTBT can be attributed to the localized p–p* transitions,
and the longer wavelength absorption bands come from the
intramolecular charge transfer (ICT) between electron-rich
donors (fluorene) and electron-deficient acceptors (BT and
DTBT).50,51 The ICT band of Hb-BFTBT (kmax: 527 nm) is at
longer wavelength than that of Hb-BFBT (kmax: 437 nm).
The bathochromic shift was also observed in the PL kmax of
the dilute solutions of Hb-TF, Hb-BFBT, and Hb-BFTBT. The
PL kmax of Hb-TF, Hb-BFBT, and Hb-BFTBT are 410, 522,
and 612 nm, respectively (Table 2 and Figs. 1–3). In addi-
tion, the optical band gaps (Eg) of the Hb-Ps deduced from
lution and in thin film.
Hb-BFBT, and Hb-BFTBT are blue, green, and red emitters.
Thus, the results demonstrate a simple methodology for tun-
ing the PL wavelength of hyperbranched conjugated poly-
mers by simply introducing the electron accepting units into
the electron-rich conjugated systems.
Compared to their dilute solutions, bathochromic shift of the
UV, and PL bands, decrease in the PL quantum yields are
observed in the thin films of Hb-TF, Hb-BFBT, and Hb-
BFTBT (Table 2 and Figs. 1–3). The phenomenon is attrib-
uted to the formation of aggregation of polymers in the solid
state. Formation of aggregation in the solid state of these
series of Hb-Ps can be expected, as the branching points
(benzene rings) possess a planar geometry rather than a
three-dimensional structure. Interestingly, the PL spectrum
of the Hb-TF thin film is extremely broad and covers exten-
sively in the blue and green light region. The result suggests
the possibility of coexistence of multiple degrees of aggrega-
tions in the thin film. Although the PL spectra of the Hb-
BFBT and Hb-BFTBT in thin film red-shifted, they remained
green and red emitters in the solid state. Because of its large
Eg and wide PL emission, the thin film of Hb-TF therefore
possesses the potential to be used as a host in PLED
the onset of absorption follows the trend that Eg,
Hb-TF
(3.04 eV) > Eg,
(2.45 eV) > Eg,
(1.97 eV).
Hb-BFTBT
Hb-BFBT
These results clearly indicate that the photophysical proper-
ties of the Hb-Ps are strongly affected, when the middle fluo-
rene moiety in the TF unit is replaced with an electron-
withdrawing group, for example, BT or DTBT. In addition to
that, the donating strength of the fluorene moiety is stronger
when the fluorene and BT moieties are bridged with a thio-
pene ring. The PL kmaxs of the polymers suggest that Hb-TF,
FIGURE 1 UV–Vis absorption and PL spectra of Hb-TF in solu-
tion and in thin film, and the absorption spectrum of
Os(fptz)2(PPh2Me2)2 in solution.
FIGURE 3 UV–Vis absorption and PL spectra of Hb-BFTBT in so-
lution and in thin film, and the PL spectrum of PFO in thin film.
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TABLE 2 Optical Properties of the Hyperbranched Polymers
UV–Vis Absorption
c
kmax (nm)
PL kmax (nm)
UPL (%)
Solutiona
Eg (eV)
Polymer
Solutiona Filmb
Solutiona
Filmb
Filmb
Filmb
Hb-TF
Hb-BFBT
Hb-BFTBT
a
365
366
410
522
612
438, 490, 544
37
50
18
8
30
7
3.04
2.45
1.97
335, 423
373, 511
340, 437
376, 527
545
655
c
In 0.5 wt % toluene.
Eg was determined from the onset wavelength of
b
Spin-coated from 0.5 wt % toluene.
UV absorption spectra in thin film.
applications or as the active layer of a white PLED when
blended with suitable amount of red emitters we synthesized
in this article.
voltage characteristics of the devices are shown in Figure 5.
The device performances are summarized in Table 4. As
shown in Figure 5(a), the EL kmax of Hb-TF, Hb-BFBT, and
Hb-BFTBT are located at 520, 560, and 664 nm, at maxi-
mum luminance efficiency. All the EL kmaxs of the devices
are similar to the PL kmaxs observed in the polymer thin
films. The EL spectrum of Hb-TF shows broad blue-green
emission, while the EL spectra of Hb-BFBT and Hb-BFTBT
refer to green and red emission. Thus, by introducing the
electron-accepting units (BT and DTBT) into an electron-rich
conjugated system, the emission spectra of the Hb-Ps-based
devices can be easily adjusted, and RGB PLEDs can be
obtained using the novel Hb-Ps as the active materials. The
broad blue-green emission is due to the aggregation of the
polymer chains in the solid state. The Hb-TF-based device
had a maximum brightness of 50 cd/m2 and maximum lumi-
nance efficiency of 0.01 cd/A. The Hb-BFBT- and Hb-
BFTBT-based devices had a maximum brightness of 42 and
29 cd/m2, and the maximum luminance efficiency of 0.02
and 0.01 cd/A, respectively. The turn-on voltage of Hb-TF,
Hb-BFBT, and Hb-BFTBT are 7.1, 6.5, and 4.4 V, respectively
(Table 4). Among these polymers, Hb-BFTBT-based device
displayed the lowest turn-on voltage than others because of
its highest EHOMO, which reduces the energy barrier for the
hole-injection from the PEDOT:PSS layer.
Electrochemical Properties
CV was used to examine the electrochemical properties and
evaluate the HOMO (highest occupied molecular orbital) lev-
els of the polymers. Table 3 summarizes the Eox, onset, EHOMO
,
and ELUMO (lowest unoccupied molecular orbital). Hb-TF, Hb-
BFBT, and Hb-BFTBT exhibited oxidation onset potentials at
about 1.42, 1.44, and 0.87 eV, respectively. Their EHOMO
energy levels are calculated as –5.82, ꢁ5.84, and –5.27 eV
based on the onset of oxidation potential of the internal
standard ferrocene (4.8 eV below vacuum). The ELUMO levels
of Hb-TF, Hb-BFBT, and Hb-BFTBT are ꢁ2.78, ꢁ3.39, and
ꢁ3.30 eV, which were deduced from their EHOMO and optical
band gaps (Eg). The ELUMO of Hb-BFBT, and Hb-BFTBT are
lower than that of Hb-TF, because of the incorporation of BT,
an electron-withdrawing group, into the conjugated system.50
As for D-A conjugated polymers, the first oxidation onset
potential is normally contributed from the electron-rich seg-
ment, the close EHOMO of Hb-TF and Hb-BFBT can be inter-
preted as the oxidation takes place first at the fluorene moi-
eties in the molecules.50 The higher EHOMO of Hb-BFTBT
could be attributed to the incorporation of thiophene units,
an electron-rich unit, into the main chain. The energy level
diagrams of the polymers are illustrated in Figure 4.
Because of its large Eg, Hb-TF has the potential to be used
as a polymeric host. To evaluate Hb-TF as a host material,
we used red electrophosphorescent, Os(fptz)2(PPh2Me2)2 as
a guest material and fabricated a multilayer device with the
configuration of ITO/PEDOT:PSS (40 nm)/Hb-TF:X wt %
Os(fptz)2(PPh2Me2)2 (60–80 nm)/TPBI (30 nm)/LiF (1 nm)/Al
Device Performance
To evaluate the PLED performances of pristine Hb-TF, Hb-
BFBT, and Hb-BFTBT, we fabricated the double-layer PLEDs
with a device configuration of ITO/PEDOT:PSS (40 nm)/
light-emitting polymer (60–80 nm)/CsF (2 nm)/Al (100 nm).
The EL spectra, the current density, and brightness versus
TABLE 3 Electrochemical Properties of the Hyperbranched
Polymers
a
b
c
Polymer
Eox, onset (V)
EHOMO (eV)
ELUMO (eV)
Hb-TF
Hb-BFBT
Hb-BFTBT
a
1.42
1.44
0.87
ꢁ5.82
ꢁ5.84
ꢁ5.27
ꢁ2.78
ꢁ3.39
ꢁ3.30
The onset oxidation potential measured by CV.
b
c
FIGURE 4 Energy level diagram for the devices having the
EHOMO is calculated based on the equation, EHOMO ¼ ꢁ4.8 þ Eox, onset
.
configuration of ITO/PEDOT:PSS/light-emitting polymer/CsF/Al.
ELUMO is calculated based on the equation, ELUMO ¼ Eg þ EHOMO
.
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FIGURE 6 (a) PL spectra and (b) EL spectra of the blends pre-
pared from Hb-TF as the host doped with the 7 and 14 wt % of
Os(fptz)2(PPh2Me2)2 as the guest.
FIGURE 5 (a) EL spectra and (b) current density and brightness
versus voltage characteristics of the devices having the config-
uration of ITO/PEDOT:PSS/light-emitting polymer/CsF/Al.
takes place once Os(fptz)2(PPh2Me2)2 is excited and subse-
quent red phosphorescence emission was generated when
excited Os(fptz)2(PPh2Me2)2 relaxes from its triplet excited
state.52 As indicated in Figure 6(a), the PL spectra of the blends
that contained Os(fptz)2(PPh2Me2)2-doped Hb-TF films exhibit
two emission bands with kmax at 435 and 616 nm. The shorter
wavelength band originates from the residual emission of the
host, and the longer wavelength band corresponds to the phos-
phorescence of the Os(fptz)2(PPh2Me2)2 guest. The result
implies that partial energy transfer moderated from the host to
the guest. Conversely, the EL spectra of Figure 6(b) exhibited
only the red emission derived from Os(fptz)2(PPh2Me2)2, sug-
gesting that both energy transfer and direct charge trapping/
recombination at the Os(fptz)2(PPh2Me2)2 guest were responsi-
ble for the observed EL.53–55 According to the energy level dia-
gram in inset of Figure 7(a), Hb-TF has much deeper HOMO
level than Os(fptz)2(PPh2Me2)2. Therefore, holes in the active
layer can be effectively trapped in the Os(fptz)2(PPh2Me2)2 do-
main. In this case, efficient charge recombination in the guest
domain and dominant phosphorescence emission of the guest
was observed.56 As shown in Table 5, the EL spectra of 7 and
14 wt % Os(fptz)2(PPh2Me2)2-doped blends show EL kmax at
616 nm, with the CIE coordinates of (0.64, 0.36) close to the
standard CIE coordinate of red emission (0.67, 0.33). Maximum
brightness of the 7, and 14 wt % Os(fptz)2(PPh2Me2)2-doped
devices are 41 and 84 cd/m2, and the maximum luminance
(100 nm). The PL and EL spectra of 7 and 14 wt %
Os(fptz)2(PPh2Me2)2-doped blends are presented in Figure 6.
The current density and brightness versus voltage characteris-
tics of 7 and 14 wt % Os(fptz)2(PPh2Me2)2-doped devices are
shown in Figure 7. Device performance is summarized in
Table 5. The PL spectrum of the Hb-TF thin film and the UV-Vis
absorption spectrum of Os(fptz)2(PPh2Me2)2 in chlorobenzene
solution shown in Figure 1 demonstrate a significant overlap
between the PL band of Hb-TF and the metal-to-ligand charge
transfer (MLCT) absorption band of Os(fptz)2(PPh2Me2)2.
Thus, an efficient Fo¨rster energy transfer can be expected
from the singlet excited state of the host to the MLCT state of
the guest, Os(fptz)2(PPh2Me2)2. A fast intersystem crossing
TABLE 4 Performances of the Devices Based on the
Configuration of ITO/PEDOT:PSS/Light-Emitting Polymer/CsF/Al
Polymer
Hb-TF
7.1
Hb-BFBT
6.5
Hb-BFTBT
Turn-on voltage (V)a
Max. Brightness (cd/m2) 48 @ 12 V 42 @ 13 V
4.4
29 @ 9 V
0.01
Max. L.E. (cd/A)
EL kmax (nm)
CIE (x, y)
0.01
520
0.02
560
664
(0.30, 0.39) (0.43, 0.54) (0.67, 0.32)
a
Recorded at 1 cd/m2.
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FIGURE 8 (a) PL spectra and (b) EL spectra of the blends pre-
pared from PFO as the host doped with the 0.25, 0.5, 2, and
5 wt % of Hb-BFTBT as the guest.
FIGURE 7 (a) Current density and brightness versus voltage
characteristics and (b) luminance efficiency versus current den-
sity characteristics of the devices based on the configuration of
ITO/PEDOT:PSS/Hb-TF:X wt % Os(fptz)2(PPh2Me2)2/TPBI/LiF/Al.
(X ¼ 7 and 14). The inset is the energy level diagram for the
Os(fptz)2(PPh2Me2)2-doped devices.
directly injected into the guest molecules at sufficiently high
doping concentration; consequently, the guest domain serves
as extra transport channels for the charge carriers and
reduces the turn-on voltage.57–62 Hb-TF provides an good
packing environment for the dispersed Os(fptz)2(PPh2Me2)2
emitters and improves the device efficiency as a result of the
reductions in the degrees of both triplet–triplet annihilation
and self-quenching of the Os(fptz)2(PPh2Me2)2 guest.63 Hence,
the results demonstrate the potential of Hb-TF as a good
polymeric host in the PLED applications.
efficiency of the two devices are 1.37 and 1.61 cd/A. The
turn-on voltage of 7 and 14 wt % Os(fptz)2(PPh2Me2)2-doped
devices are 6.6 and 5.6 V. Thus, increasing the dopant concen-
tration not only enhances the device performance of Hb-TF-
based PLEDs but also decreases their turn-on voltage. The
decrease of turn-on voltage suggests that the charges can be
The PL and EL spectra of pristine Hb-BFTBT illustrate its
potential as a red emitter. To further improve the device per-
formance of Hb-BFTBT-based PLEDs, we used PFO as a host
and Hb-BFTBT as the guest and fabricated double layer red
PLEDs with the configuration of ITO/PEDOT:PSS (40 nm)/
PFO:X wt % Hb-BFTBT (60–80 nm)/CsF (2 nm)/Al (100
nm). Figure 3 displays the PL spectrum of PFO in thin film.
The emission band of PFO overlaps with the absorption
band of the Hb-BFTBT thin film, suggesting efficient energy
transfer from the PFO host to the Hb-BFTBT guest.44,45 The
PL and EL spectra of the PFO:Hb-BFTBT blends with Hb-
BFTBT concentrations of 0.25–5 wt % are presented in
Figure 8. The current density and brightness versus voltage
characteristics of the devices are shown in Figure 9. Device
performances are summarized in Table 6. As shown in Fig-
ure 8, both of the PL and EL spectra of the blends contain
TABLE 5 Performances of the Devices Based on the
Configuration of ITO/PEDOT:PSS/Hb-TF:X wt%
Os(fptz)2(PPh2Me2)2/TPBI/LiF/Al
Guest
Os(fptz)2(PPh2Me2)2
Dopant concentration (wt %)
Turn-on voltage (V)a
Max. Brightness (cd/m2)
Max. L.E. (cd/A)
7
6.6
14
5.6
41 @ 10.5 V
1.37
84 @ 10.5 V
1.61
EL kmax (nm)b
616
616
CIE (x, y)b
(0.64, 0.36)
(0.64, 0.36)
a
Recorded at 1 cd/m2.
b
Recorded at 8 V.
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centration of 5 wt %, the host emission is almost extinct.
According to the energy level diagram in inset of Figure 9(a),
the EHOMO of Hb-BFTBT is 0.5 eV below the EHOMO of PFO.
Therefore, holes can be effectively trapped in the Hb-BFTBT
domains and allows efficient emission from the guest mole-
cules.56 The EL spectrum of the device using PFO:5 wt %
Hb-BFTBT as a emitting layer shows saturated red emission
with kmax at 638 nm and CIE coordinates at (0.63, 0.34). The
maximum brightness and maximum luminance efficiency of
the device are 538 cd/m2 and 0.41 cd/A, which exhibited
better performance than those of the pristine Hb-BFTBT-
based PLEDs.64 The turn-on voltage of the device is 10.1 V,
which is higher than that of the pristine Hb-BFTBT. To fur-
ther improve the performance of the device, inserting a hole-
transporting layer or adding hole-transporting material into
the PFO:Hb-BFTBT blend is now in progress in our group.
As shown in Figure 9 and Table 6, the device with the lowest
Hb-BFTBT dopant concentration (0.25 wt %) show the best
performance with turn-on voltage at 5.1 V, a maximum
brightness of 1169 cd/m2, and maximum luminance effi-
ciency of 3.39 cd/A. The EL spectra of the device contain
both blue (kmax at 440 nm) and red (kmax at 609 nm) emis-
sion bands with similar intensities [Fig. 8(a)]. The CIE coor-
dinates of the device is at (0.53, 0.32). The incomplete
energy transfer from PFO to Hb-BFTBT provides an oppor-
tunity of making white PLEDs via adding an auxiliary green
dopant. For this purpose, an efficient green emitter, BFBT
was added into the PFO:Hb-BFTBT blend.46 White PLEDs
with the double-layer configuration of ITO/PEDOT:PSS
(40 nm)/PFO:X wt % BFBT:Y wt % Hb-BFTBT (60–80 nm)/
CsF (2 nm)/Al (100 nm) were fabricated. Several concentra-
tions of BFBT:Hb-BFTBT were attempted to achieve the
ideal white light emission. The performances of the devices
are summarized in Table 7. The current density and bright-
ness versus voltage characteristics and the luminance effi-
ciency versus current density curves of the devices are
shown in Figure 10. The inset of Figure 10(a) shows the EL
spectra of the devices at an applied potential of 6 V. At dop-
ant concentrations of 0.05, 0.08, and 0.1 wt % for both BFBT
and Hb-BFTBT, the devices have a maximum brightness of
1183, 1185, and 1886 cd/m2 and maximum luminance
FIGURE 9 (a) Current density and brightness versus voltage
characteristics and (b) luminance efficiency versus current den-
sity characteristics of the devices based on the configuration of
ITO/PEDOT:PSS/PFO:X wt % Hb-BFTBT/CsF/Al (X ¼ 0.25, 0.5, 2,
and 5). The inset is the energy level diagram for the Hb-BFTBT-
doped devices.
two emission bands. The one with kmax at 440 nm, belongs
to the characteristics emission of the PFO host, while the
other one with kmax at 609 nm, belongs to the emission of
the HB-BFTBT guest. The degree of energy transfer from the
PFO host to the Hb-BFTBT guest increases as the doping con-
centration increases from 0.25 to 5 wt %.53–55 At dopant con-
TABLE 6 Performances of the Devices Based on the Configuration of ITO/PEDOT:PSS/PFO:X
wt% Hb-BFTBT/CsF/Al
Guest
Hb-BFTBT
Dopant concentration (wt %)
Turn-on voltage (V)a
Brightness (cd/m2)b
L.E. (cd/A)b
0.25
5.0
0.5
5.1
2
7.7
5
10.1
369
329
188
74
1.99
1.97
0.97
0.37
Max. Brightness (cd/m2)
Max. L.E. (cd/A)
ELc
1,187
2.42
1,169
3.39
643
538
1.96
0.41
616
620
620
638
CIE (x, y)c
(0.45, 0.29)
(0.53, 0.32)
(0.60, 0.34)
(0.63, 0.34)
a
c
Recorded at 1 cd/m2.
Recorded at 20 mA/cm2.
Recorded at 11 V.
b
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TABLE 7 Performances of the Devices Based on the Configuration of ITO/PEDOT:PSS/PFO:X wt %
BFBT:Y wt % Hb-BFTBT/CsF/Al
Guest
BFBT:Hb-BFTBT
Dopant concentration (wt %)
Turn-on voltage (V)a
Brightness (cd/m2)b
L.E. (cd/A)b
0.05:0.05
3.5
0.08:0.08
0.1:0.1
3.5
0.25:0.25
3.5
3.5
648
547
645
445
2.82
3.26
3.27
2.24
Max. Brightness (cd/m2)
1,183
3.7
1,185
1,886
3.71
1,037
3.1
Max. L.E. (cd/A)
4.98
CIE (x, y)c
(0.31, 0.34)
(0.33, 0.37)
(0.35, 0.38)
(0.42, 0.40)
a
c
Recorded at 1 cd/m2.
Recorded at 20 mA/cm2.
Recorded at 6 V.
b
efficiency of 3.70, 4.98, and 3.71 cd/A. Their CIE coordinates
are (0.31, 0.34), (0.33, 0.37), and (0.35, 0.38), which are all
very close to the CIE coordinates of the ideal white light,
(0.33, 0.33). The turn-on voltages of all the devices are 3.5 V.
Further increase of the dopant concentration to 0.25 wt %
lowered the device performance, deviated the EL of the
device from white emission. These results demonstrated the
potential of Hb-BFTBT as a red emitter, and as a component
in the applications of white PLEDs.
CONCLUSIONS
In summary, to achieve good control in the color stability of
solution-processable light-emitting materials, we developed a
facile approach to synthesize diyne-functionalized TF, BFBT,
and BFTBT as the blue, green, and red monomeric chromo-
phores and prepared the corresponding blue, green, and red
emitting Hb-Ps, Hb-TF, Hb-BFBT, and Hb-BFTBT through the
[2þ2þ2] polycyclotrimerization. All the synthesized Hb-Ps
show excellent thermal stability, moderate to high Tgs, and can
be fabricated into the active layers of PLEDs based on the solu-
tion process. PL and EL spectra of the Hb-Ps clearly demon-
strate that Hb-TF, Hb-BFBT, and Hb-BFTBT are blue-green,
green, and red emitting materials. Because of its large Eg, Hb-
TF was further evaluated as a polymeric host material. Satu-
rated red electrophosphorescent devices with CIE coordinates
of (0.64, 0.36), turn-on voltage (5.6 V) with a maximum lumi-
nance efficiency of 1.61 cd/A, and maximum brightness of
84 cd/m2 were obtained when a Hb-TF was used as a host
material doped with Os(fptz)2(PPh2Me2)2 as a guest material.
The device efficiency of the red emitter, Hb-BFTBT, was further
improved in a host–guest doped system by using Hb-BFTBT as
red-emitting guest in the PFO host layer. Furthermore, a series
of efficient white PLEDs were prepared by using BFBT, as aux-
iliary green dopant in the PFO:Hb-BFTBT blend. White PLEDs
with CIE coordinates of (0.33, 0.37), which is close to that of
ideal white light (0.33, 0.33), low turn-on voltage (3.5 V) with
highest luminance efficiency of 4.98 cd/A, and maximum
brightness of 1185 cd/m2 were also achieved.
The authors thank the National Science Council and Ministry of
Education for financial support.
REFERENCES AND NOTES
FIGURE 10 (a) Current density and brightness versus voltage
characteristics and (b) luminance efficiency versus current den-
sity characteristics of the devices based on the configuration of
ITO/PEDOT:PSS/PFO:X wt % BFBT:Y wt % Hb-BFTBT/CsF/Al (X
¼ 0.05, 0.08, 0.1, and 0.25, Y ¼ 0.05, 0.08, 0.1, and 0.25). The
inset is the EL spectra of the PFO-based devices codoped with
BFBT and Hb-BFTBT at an applied potential of 6 V.
1 Burroughes, J. H.; Bradley, D. D. C.; Brown, A. R.; Marks, R.
N.; Mackay, K.; Friend, R. H.; Burn, P. L.; Holmes, A. B. Nature
1990, 347, 539–541.
2 Tasch, S.; List, E. J. E.; Ekstrom, O.; Graupner, W.; Leising,
G.; Schlichting, P.; Rohr, U.; Geerts, Y.; Scherf, U.; Mullen, K.
¨
Appl. Phys. Lett. 1997, 71, 2883–2885.
¨
708
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 50, 696–710

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
3 Yang, S. H.; Hsu, C. S. J. Polym. Sci. Polym. Chem. 2009, 47,
32 Voit, B. J. Polym. Sci. Part A: Polym. Chem. 2005, 43,
2713–2733.
2679–2699.
4 Muler, C. D.; Falcou, A.; Reckefuss, N.; Rojahn, M.; Wieder-
hirn, V.; Rudati, P.; Frohne, H.; Nuyken, O.; Becker, H.; Meer-
holz, K. Nature 2003, 421, 829–833.
33 Gregson, C. K. A.; Gibson, V. C.; Long, N. J.; Marshall, E. L.;
Oxford, P. J.; White, A. J. P. J. Am. Chem. Soc. 2006, 128,
7410–7411.
¨
5 Pei, Q.; Yang, Y. J. Am. Chem. Soc. 1996, 118, 7416–7417.
34 Liu, J.; Zhang, L.; Lam, J. W. Y.; Jim, C. K. W.; Yue, Y.;
Deng, R.; Hong, Y.; Qin, A.; Sung, H. H. Y.; Williams, I. D.; Jia,
G.; Tang, B. Z. Macromolecules 2009, 42, 7367–7378.
6 Virgili, T.; Lidzey, D. G.; Bradley, D. D. C. Adv. Mater. 2000,
12, 58–62.
35 Xu, K.; Peng, H.; Sun, Q.; Dong, Y.; Salhi, F.; Luo, J.; Chen,
J.; Huang, Y.; Zhang, D.; Xu, Z.; Tang, B. Z. Macromolecules
2002, 35, 5821–5834.
7 Leclerc, M. J. Polym. Sci. Part A: Polym. Chem. 2001, 39,
2867–2873.
8 Scherf, U.; List, E. J. W. Adv. Mater. 2002, 14, 477–487.
9 Li, J.; Bo, Z. S. Macromolecules 2004, 37, 2013–2015.
36 Peng, H.; Cheng, L.; Luo, J.; Xu, K.; Sun, Q.; Dong, Y.; Salhi,
F.; Lee, P. P. S.; Chen, J; Tang, B. Z. Macromolecules 2002, 35,
5349–5351.
10 Herguth, P.; Jiang, X.; Liu, M. S.; Jen, A. K. Y. Macromole-
cules 2002, 35, 6094–6100.
37 Zheng, R. H.; Dong, H. C.; Peng, H.; Lam, J. W. Y.; Tang, B.
Z. Macromolecules 2004, 37, 5196–5210.
11 Hou, Q.; Xu, Y.; Yang, W.; Yuan, M.; Peng, J.; Cao, Y.
J. Mater. Chem. 2002, 12, 2887–2892.
38 Chen, J.; Peng, H.; Law, C. C. W.; Dong, Y.; Lam,
J. W. Y.; Williams, I. D.; Tang, B. Z. Macromolecules 2003,
36, 4319–4327.
12 Chuang, C. Y.; Shih, P. I.; Chien, C. H.; Wu, F. I.; Shu, C. F.
Macromolecules 2007, 40, 247–252.
13 Geng, Y.; Trajkovska, A.; Katsis, D.; Ou, J. J.; Culligan, S.
W.; Chen, S. H. J. Am. Chem. Soc. 2002, 124, 8337–8347.
39 Haussler, M.; Qin, A.; Tang, B. Z. Polymer 2007, 48,
6181–6204.
14 Wong, K. T.; Chien, Y. Y.; Chen, R. T.; Wang, C. F.; Lin, Y.
T.; Chiang, H. H.; Hsieh, P. Y.; Wu, C. C.; Chou, C. H.; Su, Y. O.;
Lee, G. H.; Peng, S. M. J. Am. Chem. Soc. 2002, 124,
11576–11577.
40 Liu, J. Z.; Zheng, R. H.; Tang, Y. H.; Haussler, M.; Lam, J. W.
Y.; Qin, A.; Ye, M. X.; Hung, Y. N.; Gao, P.; Tang, B. Z. Macro-
molecoles 2007, 40, 7473–7486.
41 Jim, C. K. W.; Qin, A.; Lam. J. W. Y.; Haussler, M.; Liu, J.;
Yuen, M. M. F.; Kim, J. K.; Ng, K. M.; Tang, B. Z. Macromole-
cules 2009, 42, 4099–4109.
15 Wu, C. C.; Liu, T. L.; Hung, W. Y.; Lin, Y. T.; Wong, K. T.;
Chen, R. T.; Chen, Y. M.; Chien, Y. Y. J. Am. Chem. Soc. 2003,
125, 3710–3711.
42 Liu, J.; Zhong, Y.; Lam, J. W. Y.; Lu, P.; Hong, Y.; Yu, Y.;
Yue, Y.; Faisal, M.; Sung, H. H. Y.; Williams, I. D.; Wong, K. S.;
Tang, B. Z. Macromolecules 2010, 43, 4921–4936.
16 Wu, C. C.; Liu, W. G.; Hung, W. Y.; Liu, T. H.; Lin, Y. T.; Lin,
H. W.; Wong, K. T.; Chien, Y. Y.; Chen, R. T.; Hung, T. H.; Chao,
T. C.; Chen, Y. M. Appl. Phys. Lett. 2005, 87, 052103-1–052103-3.
43 Wu, F. I.; Shih, P. I.; Shu, C. F.; Tung, Y. L.; Chi, Y. Macro-
molecules 2005, 38, 9028–9036.
17 Ku, S. Y.; Chi, L. C.; Hung, W. Y.; Yang, S. W.; Tsai, T. C.;
Wong, K. T.; Chen, Y. H.; Wu, C. I. J. Mater. Chem. 2009, 19,
773–780.
44 Su, H. J.; Wu, F. I.; Shu, C. F. Macromolecules 2004, 37,
7197–7209.
18 Geng, Y.; Chen, A. C. A.; Ou, J. J.; Chen, S. A.; Klubek, K.;
Vaeth, K. M.; Tang, C. W. Chem. Mater. 2003, 15, 4352–4360.
45 Huang, J. S.; Li, G.; Wu, E.; Xu, Q. F.; Yang, Y. Adv. Mater.
2006, 18, 114–117.
19 Patten, T. E.; Matyjaszewski, K. Adv. Mater. 1998, 10,
901–915.
46 Cheng, Y. J.; Liao, M. H.; Shih, H. M.; Shih, P. I.; Hsu, C. S.
Macromolecules 2011, 44, 5968–5976.
20 Voit, B. J. Polym. Sci. Part A: Polym. Chem. 2000, 38,
2505–2525.
47 Malkina, A. G.; Brandsma, L.; Vasilevsky, S. F.; Trofimov, B.
A. Synthesis 1996, 1996, 589–590.
21 Jikei, M.; Kakimoto, M. Prog. Polym. Sci. 2001, 26,
1233–1285.
48 Tung, Y. L.; Lee, S. W.; Chi, Y.; Tao, Y. T.; Chien, C. H.;
Cheng, Y. M.; Chou, P. T.; Peng, S. M.; Liu, C. S. J. Mater.
Chem. 2005, 15, 460–464.
22 Tomalia, D. A.; Fre´chet, J. M. J. Polym. Sci. Part A: Polym.
Chem. 2002, 40, 2719–2728.
49 Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett.
1975, 50, 4467–4470.
23 Gao, C.; Yan, D. Prog. Polym. Sci. 2004, 29, 183–275.
24 Haussler, M.; Tang, B. Z. Adv. Polym. Sci. 2007, 209, 1–58.
50 Chen, C. H.; Cheng, Y. J.; Dubosc, M.; Hsieh, C. H.; Chu, C.
C.; Hsu, C. S. Chem. Asian J. 2010, 5, 2483–2492.
25 Liu, J.; Lam, J. W. Y.; Tang, B. Z. Chem. Rev. 2009, 109,
5799–5867.
51 Cheng, Y. J.; Wu, J. S.; Shih, P. I.; Chang, C. Y.; Jwo, P. C.;
Kao, W. S.; Hsu, C. S. Chem. Mater. 2011, 23, 2361–2369.
26 Rosen, B. M.; Wilson, C. J.; Wilson, D. A.; Peterca, M.;
Imam, M. R.; Percec, V. Chem. Rev. 2009, 109, 6275–6540.
52 Colombo, M. G.; Hauser, A.; Gudel, H. Top. Curr. Chem.
¨
27 Voit, B. I.; Lederer, A. Chem. Rev. 2009, 109, 5924–5973.
1994, 171, 144–171.
28 Maclachlam, M. J.; Ginzburg, M.; Coombs, N.; Raju, N. P.;
Greedan, J. E.; Ozin, G. A.; Manners, I. J. Am. Chem. Soc.
2000, 122, 3878–3891.
53 Uchida, M.; Adachi, C.; Koyama, T.; Taniguchi, Y. J Appl.
Phys. 1999, 86, 1680–1687.
54 Chen, F. C.; Chang, S. C.; He, G.; Pyo, S.; Yang, Y.; Kurotaki,
M.; Kido, J. J. Polym. Sci. Part B: Polym. Phys. 2003, 41,
2681–2690.
29 Yates, C. R.; Hayes, W. Eur. Polym. J. 2004, 40, 1257–1281.
30 Wong, W. Y.; Liu, L.; Poon, S. Y.; Choi, K. H.; Cheah, K. W.;
Shi, J. X. Macromolecules 2004, 37, 4496–4504.
55 Yeh, H. C.; Chein, C. H.; Shih, P. I.; Yuan, M. C.; Shu, C. F.
Macromolecules 2008, 41, 3801–3807.
31 Hinderling, C.; Keles, Y.; Stockli, T.; Knapp, H. F.; delos
Across, T.; Oelhafen, P.; Korczagin, I.; Hempenius, M. A.;
Vancso, G. J.; Pugin, R.; Heinzelmann, H. Adv. Mater. 2004,
16, 876–879.
56 Wu, F. I.; Shih, P. I.; Tseng, Y. H.; Chen, G. Y.; Chien, C. H.;
Shu, C. F.; Tung, Y. L.; Chi, Y.; Jen, A. K. Y. J. Phys. Chem. B
2005, 109, 14000–14005.
WWW.MATERIALSVIEWS.COM
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 50, 696–710
709

JOURNAL OF
POLYMER SCIENCE
ARTICLE
WWW.POLYMERCHEMISTRY.ORG
57 Adachi, C.; Baldo, M. A.; Thompson, M. E.; Forrest, S. R.
J. Appl. Phys. 2001, 90, 5048–5051.
61 Tung, Y. L.; Chen, L. S.; Chi, Y.; Chou, P. T.; Cheng, Y. M.;
Li, E. Y.; Lee, G. H.; Shu, C. F.; Wu, F. I.; Carty, A. J.; Peng, S.
M.; Lee, G. H. Adv. Funct. Mater. 2006, 16, 1615–1626.
58 Noh, Y. Y.; Lee, C. L.; Kim, J. J. J. Chem. Phys. 2003, 118,
2853–2864.
62 Wu, C. H.; Shih, P. I.; Shu, C. F.; Chi, Y. Appl. Phys. Lett.
2008, 92, 233303-1–233303-3.
59 Holmes, R. J.; D’Andrade, B. W.; Forrest, S. R.; Ren, X.; Li,
J.; Thompson, M. E. Appl. Phys. Lett. 2003, 83, 3818–3820.
63 Tsai, M. H.; Lin, H. W.; Su, H. C.; Ke, T. H.; Wu, C. C.; Fang, F. C.;
Liao, Y. L.; Wong, K. T.; Wu, C. I. Adv. Mater. 2006, 18, 1216–1220.
60 Tung, Y. L.; Lee, S. W.; Chi, Y.; Chen, L. S.; Shu, C. F.; Wu,
F. I.; Carty, A. J.; Chou, P. T.; Peng, S. M.; Lee, G. H. Adv.
Mater. 2005, 17, 1059–1064.
64 Virgili, T.; Lidzey, D. C.; Bradley, D. D. C. Synth. Met. 2000,
111–112, 203–206.
710
JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 50, 696–710