J. Zhang et al. / Polymer 54 (2013) 5525e5533
5527
1
54.23, 142.75, 133.86, 132.30, 130.0, 126.94, 113.50, 31.81, 30.78,
was dried under vacuum for 1 day to give the final product P3
ꢂ1
ꢂ1
2
7
9.71, 29.31, 22.79, 14.30. ESI-MS m/z Calcd. For C26
H
31AgBr
2
N
2
S
3
(44 mg, 24%). UV:
l
max (lg ε [L ꢁ mol ꢁ cm ]) 464 nm (5.88),
þ
33; Found (M þ H) 734.
Egsol ¼ 2.20 eV. Emission:
l
max: 621 nm. UV:
l
max,film 540 nm,
ꢂ1
Egfilm ¼ 1.84 eV. FT-IR spectra (cm ): 3067 (w, AreH), 2926 (s, CH
3
,
2
2
.4. Synthesis of the copolymers
stretching), 2851 (s, CH
373 (s, ]CH, stretching), 1167 (m, CeN, stretching), 781 (s, ]CeH,
out-of-plane deformation). GPC (g/mol): M ¼ 8000, M ¼ 15000,
3
PDI: 1.88. H NMR (400 MHz, CDCl ): d (ppm): 7.01 (s, 3H), 2.77 (s,
2
, stretching), 1448 (m, C]C, stretching),
1
.4.1. Copolymers P1 and P2egeneral procedure
n
w
1
2
,5-Dibromo-3-hexyl-thiophene,
2,5-bis-(trimethylstannyl)-
thiophene and Pd(PPh (5 mol%) were added together in a mi-
3
)
4
2H), 1.68 (s, 2H), 1.25 (d, 6H), 0.88 (s, 3H). Anal. Calcd. For P3; C,
crowave tube. Under inert conditions, THF (4 mL) was added to the
67.15; S, 25.61; H, 7.24; Found C, 66.82; S, 25.97; H, 7.21%.
reaction system and was allowed to stir in the microwave for
ꢀ
1
2 min at 150 C. After cooling down to room temperature, the
2.4.2.2. Copolymer P4. Compound M3 (157 mg, 0.25 mmol), M2
reaction solution was poured in chloroform and the combined
organic layers were washed with 2 N HCl (1 ꢁ100 mL) and NaHCO
SO and
(103 mg, 0.25 mmol), Pd(PPh
was dried under vacuum for 1 day to give the final product P4
3 4
) , (9 mg), THF (4 mL). The black solid
3
ꢂ1
ꢂ1
solutions (1 ꢁ50 mL). The organic phase was dried over Na
2
4
(52 mg, 20%). UV:
l
max (lg ε [L ꢁ mol ꢁ cm ]) 489 nm (5.60),
the solvent removed by reduced pressure. The residue was dis-
382 nm (4.14), Egsol ¼ 2.13 eV. Emission:
l
max: 683 nm. UV:
l
max,film
ꢂ1
solved in chloroform (2e4 mL), precipitated in methanol (500 mL)
540/396 nm, Egfilm ¼ 1.80 eV. FT-IR spectra (cm ): 3067 (w, AreH),
ꢀ
at 0 C and the black solid, with metallic shine, was further
2926 (s, CH
stretching), 1373 (s, ]CH, stretching), 1167 (m, CeN, stretching),
81 (s, ]CeH, out-of-plane deformation). GPC (g/mol): M
¼ 7700,
(ppm): 7.69 (s,
3 2
, stretching), 2851 (s, CH , stretching), 1448 (m, C]C,
extracted with ethanol and n-hexane.
7
n
1
2
(
.4.1.1. Copolymer P1. Compound M1 (82 mg, 0.25 mmol), M2
103 mg, 0.25 mmol), Pd(PPh , (9 mg), THF (4 mL). The black solid
was dried under vacuum for 1 day to give the final product P1
M
w
¼ 15500, PDI: 2.01. H NMR (400 MHz, CDCl
3
): d
3
)
4
2H), 7.22 (s, 2H), 7.11 (s, 2H), 2.77 (s, 4H), 1.68 (s, 4H), 1.25 (d, 12H),
0.86 (s, 4H). Anal. Calcd. For P4; C, 65.41; S, 23.28; H, 6.22; N, 5.09;
Found C, 65.67; S, 22.59; H, 6.67; N, 5.07%.
ꢂ1
ꢂ1
(
46 mg, 25%). UV:
l
max (lg ε [L ꢁ mol ꢁ cm ]) 468 nm (5.90),
Egsol ¼ 2.21 eV. Emission:
l
max: 567 nm. UV:
l
max,film 551 nm,
ꢂ1
Egfilm ¼ 1.85 eV. FT-IR spectra (cm ): 2926 (s, CH
3
, stretching),
2.5. Synthesis of the PbS NPsegeneral procedure
2
851 (s, CH
2
, stretching), 1448 (m, C]C, stretching), 1373 (s, ]CH,
stretching), 1167 (m, CeN, stretching), 781 (s, ]CeH, out-of-plane
The PbS nanoparticles were synthesized using tri-n-octylphos-
phine and oleic acid as stabilizing agents [45,46]. As synthetic
equipment a three-neck flask with condenser, a thermocouple,
heating mantle and magnetic stirrer were used. Typically, a mixture
of 0.78 g lead acetate trihydrate (2 mmol), 1.5 mL oleic acid
1
deformation). GPC (g/mol): M
NMR (400 MHz, CDCl ): (ppm): 7.01 (s, 3H), 2.77 (s, 2H), 1.68 (s,
H), 1.25 (d, 6H), 0.88 (s, 3H). Anal. Calcd. For P1; C, 67.15; S, 25.61;
H, 7.24; Found C, 67.45; S, 25.26; H, 7.29%.
n
¼ 8200, M
w
¼ 14900, PDI: 1.82. H
3
d
2
(4.7 mmol), 4 mL distilled tri-n-octylphosphine (9 mmol) and
2
(
.4.1.2. Copolymer P2. Compound M3 (157 mg, 0.25 mmol), M2
103 mg, 0.25 mmol), Pd(PPh , (9 mg), THF (4 mL). The black solid
was dried under vacuum for 1 day to give the final product P2
6 mL diphenylether (38 mmol) were heated under vacuum for
1 h at 80 C. The sulfur precursor solution, comprising 0.05 g thi-
ꢀ
3
)
4
oacetamide (0.67 mmol), 0.25 mL N,N-dimethylformamide
(3.3 mmol) and 6 mL tri-n-octylphosphine (13.5 mmol) was
ꢂ1
ꢂ1
(
57 mg, 22%). UV:
l
max (lg ε [L ꢁ mol ꢁ cm ]) 493 nm (5.74),
ꢀ
3
5
84 nm (3.90), Egsol ¼ 2.13 eV. Emission:
l
max: 662 nm. UV:
l
max,film
injected at 150 C under nitrogen and the reaction was quenched
ꢂ1
42/401 nm, Egfilm ¼ 1.81 eV. FT-IR spectra (cm ): 2926 (s, CH
3
,
after 5 min. Subsequently, the particle solution was cleaned by
precipitation from 1-butanol. The precipitate was washed two
times with 1-butanol and afterwards re-dissolved in an organic
solvent. For spectroscopic investigations tetrachloroethylene or
toluene were used as solvents.
stretching), 2851 (s, CH
373 (s, ]CH, stretching), 1167 (m, CeN, stretching), 781 (s, ]CeH,
out-of-plane deformation). GPC (g/mol): M ¼ 16000,
¼ 7900, M
(ppm): 7.69 (s, 2H), 7.22 (s,
H), 7.11 (s, 2H), 2.77 (s, 4H), 1.68 (s, 4H), 1.25 (d, 12H), 0.86 (s, 4H).
Anal. Calcd. For P2; C, 65.41; S, 23.28; H, 6.22; N, 5.09; Found C,
2
, stretching), 1448 (m, C]C, stretching),
1
n
w
1
3
PDI: 2.03. H NMR (400 MHz, CDCl ): d
2
2.6. Synthesis of the PbS-copolymer compositesegeneral procedure
6
5.56; S, 22.8; H, 6.58; N, 5.06%.
In general, PbS-copolymer composites NC3 and NC4 were syn-
thesized by treatment of PbS nanoparticles with P3 and P4. First,
the PbS nanoparticles (5 mg) were mixed in 1 mL of a solution of
THF with the thiol-functionalized polymer (10 mg/mL) and stirred
overnight. After precipitation from ethanol, washing two times
with n-butanol and drying under vacuum, two nanocomposite
(NC)-like materials NC3 and NC4 were obtained as powders.
2
.4.2. Copolymers P3 and P4egeneral procedure
4
,7-Bis-(5-bromo-3-hexyl-thiophen-2-yl)-benzo[c][1,2,5]-thia-
diazole, 2,5-bis-(trimethylstannyl)-thiophene and Pd(PPh (5 mol
) were added together in a microwave tube. Under argon, THF
3 4
)
%
(
4 mL) was added to the reaction system and was allowed to stir in
ꢀ
the microwave for 12 min at 150 C. Subsequently, the reaction
system was endcapped by using 4-bromobenzenethiol for 2 min at
ꢀ
1
50 C. After cooling down to room temperature the reaction so-
2.7. Fabrication and measurement of the solar cells
lution was poured in chloroform and the combined organic layers
were washed with 2 N HCl (1 ꢁ 100 mL) and NaHCO solutions
SO and the
3
Solar cells were fabricated on ITO-coated glass substrates
(
1 ꢁ 50 mL). The organic phase was dried over Na
2
4
(ShinAn SNP, R
,
¼ 13 U/,), which were cleaned in acetone and
solvent removed by reduced pressure. The residue was dissolved in
isopropanol by ultrasonication for 15 min each. Subsequently, the
substrates were exposed to oxygen plasma and transferred into a
glove box, where they were kept under nitrogen atmosphere for
the rest of the fabrication and characterization process. A layer of
low-conductive PEDOT:PSS (CleviosÔ P VP AI 4083) was spin-
casted onto the substrate followed by the active layer from a
blend comprising the polymers P3, P4 or the nanocompound NC3
ꢀ
chloroform (2e4 mL), precipitated in methanol (500 mL) at 0
C
and the black solid, with metallic shine, was further extracted with
ethanol and n-hexane.
2.4.2.1. Copolymer P3. Compound M1 (82 mg, 0.25 mmol), M2
(
103 mg, 0.25 mmol), Pd(PPh , (9 mg), THF (4 mL). The black solid
3 4
)