traditional PBI-based materials was successfully suppressed
using a precise molecular design.34,40 Furthermore, the OPV
using the PBI-based small molecule as a non-fullerene acceptor
material achieved an excellent PCE over 4% in a non-fullerene
OPV, indicating the huge potential of PBI-based small mole-
cules as acceptor materials. Other researchers also reported the
potential results of PBI-based small molecules as non-fullerene
acceptor materials in OPVs.41-43
7.50 (dd, 2H, J = 5.2, 0.8 Hz), 7.32 (dd, 2H, J = 4.8, 1.2 Hz),
7.19 (t, 2H, J = 5.6 Hz), 4.11 (d, 4H, J = 7.2 Hz), 1.94 (m,
2H), 1.45-1.15, (m, 80H), 0.88 (m, 12H). 13C NMR (CDCl3, ¤,
ppm): 163.7, 163.6, 143.6, 135.7, 134.4, 133.2, 133.1, 129.7,
129.0, 128.4, 127.8, 127.5, 122.2, 122.1, 44.8, 36.7, 32.0,
31.8, 30.1, 29.8, 29.5, 26.6, 22.8, 14.2. Anal. Calcd for
C80H110N2O4S2: C, 78.25; H, 9.03; N, 2.28. Found: C, 78.01;
H, 9.15; N, 2.20.
Herein, we present a series of PBI-based small molecules
with the D-A architecture (PBI1, PBI2, and PBI3). PBI1-3
were synthesized systematically by typical Stille coupling reac-
tions between traditional dibromo PBI monomer and thiophene
derivatives with tributylstannyl functionalities. The tuning of
optical, electrochemical, and thermal properties, and nano-
morphology of PBI1-3 derived from the D-A architecture was
also investigated in detail.
Synthesis of PBI2. A dry toluene solution (5 mL) of 1
(244 mg, 0.2 mmol), T2 (273 mg, 0.6 mmol), and [Pd(PPh3)4]
(11.6 mg, 0.01 mmol) was refluxed at 120 °C for 16 h under
a nitrogen atmosphere. After the reaction, the solvents were
removed. The residue was purified with column chromatog-
raphy (chloroform/hexane = 3/2) to yield a purple solid (75.0
1
mg, 27%). H NMR (CDCl3, ¤, ppm): 8.68 (s, 2H), 8.31 (m,
4H), 7.29 (d, 2H, J = 4.8 Hz), 7.23 (m, 4H), 7.20 (d, 2H,
J = 4.4 Hz), 7.05 (m, 2H), 4.11 (d, 4H, J = 7.2 Hz), 1.97 (m,
2H), 1.45-1.13 (m, 80H), 0.90 (m, 12H). 13C NMR (CDCl3, ¤,
ppm): 163.5, 163.4, 142.0, 140.6, 136.6, 135.4, 134.0, 132.7,
132.6, 129.7, 128.9, 128.6, 128.1, 127.6, 125.4, 125.2, 124.6,
122.2, 122.1, 44.9, 36.7, 32.0, 31.8, 30.2, 29.8, 29.5, 26.6,
22.8, 14.2. Anal. Calcd for C88H114N2O4S4: C, 75.92; H, 8.25;
N, 2.01. Found: C, 75.70; H, 8.26; N, 2.10.
2. Experimental
Materials. All reagents and solvents were used as received
unless otherwise stated. N,N-Bis(2-decyl-1-tetradecyl)-1,7-di-
bromoperylene-3,4,9,10-tetracarboxylic acid bisimide (1),15,44
and 5-(tributylstannyl)-2,2¤-bithiophene (T2)45 were synthe-
sized according to the previous literature. 5-Tributylstannyl-
terthiophene (T3) was synthesized by reference to the synthesis
of T2.
Synthesis of PBI3. A dry toluene solution (5 mL) of 1
(244 mg, 0.2 mmol), T3 (322 mg, 0.6 mmol), and [Pd(PPh3)4]
(11.6 mg, 0.01 mmol) was refluxed at 120 °C for 16 h under a
nitrogen atmosphere. After the reaction, the solvents were re-
moved. The residue was purified with column chromatography
(chloroform/hexane = 2/3) to yield a green solid (93.4 mg,
Characterization.
The 1H and 13C NMR spectra were
recorded with a JEOL JNM-ECX400. The UV-vis spectra were
recorded on a JASCO V-630BIO UV-vis spectrophotometer.
Elemental analysis was carried out on a Perkin-Elmer 2400 II
CHNS/O analyzer. Cyclic voltammetry (CV) experiments
were performed on a BAS electrochemical analyzer (model
660C) in benzene/acetnitrile (10/3, vol/vol) solutions with
0.1 M tetrabutylammonium hexafluorophosphate as a support-
ing electrolyte. A three-electrode cell was used with platinum
electrodes as both the counter and working electrodes. Silver/
silver ion (Ag in 0.1 M AgNO3 solution) was used as the ref-
erence electrode. Ferrocene/Ferrocenium (Fc/Fc+) was used
as an internal standard. The potential values obtained in ref-
erence to Ag/Ag+ were converted to the values relative to the
saturated calomel electrode (SCE). Thermal gravimetric (TG)
analysis was performed on a SEIKO SSC6200 at a heating rate
1
30%). H NMR (CDCl3, ¤, ppm): 8.69 (s, 2H), 8.33 (m, 4H),
7.27 (m, 2H), 7.23 (m, 2H), 7.20 (d, 2H, J = 3.6 Hz), 7.11 (m,
6H), 7.04 (m, 2H), 4.12 (d, 4H, J = 6.8 Hz), 1.99 (m, 2H),
1.45-1.10 (m, 80H), 0.90 (m, 12H). 13C NMR (CDCl3, ¤,
ppm): 163.4, 163.3, 142.6, 142.2, 140.3, 139.9, 137.3, 136.8,
135.3, 135.1, 133.9, 132.6, 132.4, 129.7, 128.9, 128.7, 128.0,
127.6, 125.2, 125.0, 124.9, 124.5, 124.1, 122.2, 44.9, 36.8,
32.0, 31.8, 30.2, 29.8, 29.5, 26.6, 22.8, 14.2. Anal. Calcd for
C96H118N2O4S6: C, 74.08; H, 7.64; N, 1.80. Found: C, 74.30;
H, 7.47; N, 1.90.
3. Results and Discussion
¹1
of 10 °C min under nitrogen atmosphere. Differential scan-
N,N-Bis(2-decyl-1-tetradecyl)-1,7-dibromoperylene-3,4,9,10-
tetracarboxylic acid bisimide (1) was synthesized by the N-
alkylation between 1,7-dibromoperylene-3,4,9,10-tetracarbox-
ylic acid bisanhydride and 2-decyl-1-tetradecylamine in acetic
acid as described in previous literature.15,44 Two thiophene
derivatives with tributylstannyl functionality (T2 and T3) were
synthesized from the corresponding bromothiophene deriva-
tives (5-bromo-2,2¤-bithiophene and 5-bromo-2,2¤:5¤,2¤¤-terthio-
phene, respectively) by treatment with n-BuLi and Bu3SnCl.45
The structures of 1, T2, and T3 were characterized by 1H NMR
measurements. Stille coupling was then carried out at 120 °C
for 16 h between 1 and 2-(tributylstannyl)thiophene (T1) in
the presence of [Pd(PPh3)4] (Scheme 1). After the reaction, the
obtained products were purified with column chromatography
(chloroform/hexane = 3/2) to yield a purple viscous solid
ning calorimetry (DSC) analysis was performed on a Seiko
¹1
EXSTAR 6000 DSC 6200 at a heating rate of 10 °C min
under a nitrogen atmosphere. Grazing incidence wide angle
X-ray scattering (GIWAXS) experiments were conducted at the
Spring-8 on beamline BL19B2. The sample was irradiated at a
fixed incident angle on the order of 0.12° through a Hubber
diffractometer with an X-ray energy of 12.39 keV (- = 1 ¡),
and the GIXD patterns were recorded with a 2-D image
detector (Pilatus 300K).
Synthesis of PBI1. A dry toluene solution (5 mL) of 1
(244 mg, 0.2 mmol), 2-(tributylstannyl)thiophene (T1) (224 mg,
0.6 mmol), and [Pd(PPh3)4] (11.6 mg, 0.01 mmol) was refluxed
at 120 °C for 16 h under a nitrogen atmosphere. After the reac-
tion, the solvents were removed. The residue was purified with
column chromatography (chloroform/hexane = 3/2) to yield a
purple viscous solid (155 mg, 63%). 1H NMR (CDCl3, ¤, ppm):
8.65 (s, 2H), 8.24 (d, 2H, J = 8.4 Hz), 8.05 (d, 2H, J = 8.0 Hz),
1
(PBI1). The structure of PBI1 was characterized by H and
13C NMR measurements to determine the synthesis of desired
PBI1 (Figure 1). PBI2 and PBI3 were also synthesized by
© 2016 The Chemical Society of Japan