Supporting Information

Polarity Engineering of Conjugated Polymers by

Variation of Chemical Linkages Connecting

Conjugated Backbones

Hui-Jun Yun,2 Hyun Ho Choi,1 Soon-Ki Kwon,2,* Yun-Hi Kim,3,* and Kilwon Cho1,*

1Department of Chemical Engineering and Center for Advanced Soft Electronics, Pohang University

of Science and Technology (POSTECH), Pohang 790-784, Korea

2School of Materials Science and Engineering and Research Institute for Green Energy Convergence

Technology (REGET), Gyeongsang National University, Jinju 660-701, Korea

3Department of Chemistry, Gyeongsang National University and Research Institute of Nature

Science (RINS), Jinju 660-701, Korea

KEYWORDS thienoisoindigo, chemical linkage, polarity, organic transistor

 

Materials.

All chemicals were purchased from Aldrich, Alpha, TCI: 3-bromothiophene, dimethyl aminoethanol,

potassium phosphate tribasic, triethylamine, oxalyl dichloride, o-xylene, Lawessons’s Reaent and NBS

were used without further purification. (E)-1,2-bis(5-(trimethylstannyl)thiophen-2-yl)ethene, (E)-

1,2-bis(5-(trimethylstannyl)selenophen-2-yl)ethene, 1,2-bis(5-(trimethylstannyl)thiophen-2-yl)ethyne,

and (E)-2,3-bis(5-(trimethylstannyl)thiophen-2-yl)acrylonitrile were synthesized via published

literature procedures.

Synthesis of Compound 1.

3-Bromothiophene (5.00 g, 30.65 mmol), 15-(6-bromohexyl)hentriacontane (30 g, 70.78 mmol),

copper (0.097 g, 1.533 mmol), copper(I) iodide (0.292 g, 1.533 mmol) and Potassium phosphate

tribasic (13.02 g, 61.3 mmol) were stirred in 50 mL of dimethyl aminoethanol at 80°C for 48 h. The

mixture was filtered and solvent was removed by vacuum. The crude product was then purified by

chromatography over silica gel (2.5% EtOAc/hexanes). Yield of N-(7-decylnonadecyl)thiophen-3-

amine was about 30%. 1H-NMR (CDCl3, 300 MHz): δ/ppm: 7.18 (m, 1H), 6.64 (m, 1H), 5.97 (m, 1H),

3.57 (m, 1H), 3.11-3.06 (t, 2H), 1.66-1.62 (m, 2H), 1.42-1.24 (bm, 49H), 0.92-0.90 (m, 6H). 13C- NMR

(CDCl3, 125 MHz): 149.15, 124.99, 119.96, 94.80, 42.65, 37.82, 34.10, 32.32, 30.55, 30.39, 30.113,

30.054, 29.75, 27.34, 27.12, 27.05, 23.08, 14.49. TOF MS ES+(m/e): 505.93 (M+, 100%).

Synthesis of Compound 2.

N-(7-decylnonadecyl)thiophen-3-amine (7.8 g, 15.41 mmol) in 35 mL of DCM was added dropwise

to oxalyl dichloride (1.79 mL, 2.08 mmol) in 50 mL of DCM at 0°C. After 30 min, triethylamine (16

mL, 7.01 mmol) in 12 mL of DCM was added dropwise and stirred overnight at room temperature.

Solvents were removed under vacuum and crude product was purified by chromatography on silica

gel in hexane : ethyl acetate mixture. 4-(7-decylnonadecyl)-4H-thieno[3,2-b]pyrrole-5,6-dione was

obtained as red oil in 47 % yield. 1H-NMR (CDCl3, 300 MHz): δ/ppm: 8.01-8.00 (d, 1H), 6.80-6.79

(m, 1H), 3.69-3.65 (t, 2H), 1.71-1.66 (m, 2H), 1.34-1.22 (bm, 49H), 0.91-0.87 (m, 6H). 13C- NMR

(CDCl3, 125 MHz): 173.08, 165.19, 161.46, 143.87, 112.94, 111.04, 42.16, 37.35, 31.94, 30.17, 29.74,

29.68, 29.39, 28.24, 26.85, 26.69, 26.54, 22.72, 14.16. TOF MS ES+(m/e): 434.31 (M+, 100%).

Synthesis of Compound 3, TIID.

A solution of 4-(7-decylnonadecyl)-4H-thieno[3,2-b]pyrrole-5,6-dione (1.00 g, 1.78 mmol) and

Lawesson's Reagent (0.362 g, 0.89 mmol) in 15 mL o-xylene were stirred at 60°C for 3 h. Progress of

reaction was monitored by TLC and change in colour (from red to violet blue). The reaction mixture

was then cooled down to room temperature. After removal of solvent, the crude product was purified

by chromatography on silica gel in hexane : DCM mixture. Yield 35 %. 1H-NMR (CDCl3, 300 MHz):

δ/ppm: 7.56-7.54 (d, 2H), 6.84-6.82 (d, 2H), 3.85-3.80 (m, 4H), 1.77-1.72 (m, 4H), 1.39-1.14 (bm,

98H), 0.91-0.84 (m, 12H). 13C-NMR (CDCl3,300 MHz): δ/ppm: 176.83, 170.51, 136.93, 153.65,

113.40, 110.79, 48.65, 36.95, 33.60, 31.95, 29.74, 29.69, 29.54, 29.39, 26.85, 26.68, 22.72, 22.67,

14.15. TOF MS ES+(m/e): 1086.89 (M+, 100%).

Synthesis of TIIDBr.

N-Bromosuccinimide (NBS, 1.12 g, 6.32 mmol) was added slowly to a solution of compound 3 (3.20

g, 2.94 mmol) in CHCl3 (200 mL). The solution was protected from light and stirred at room

temperature for 24 h. The reaction mixture was poured into water (150 mL) and extracted in CH2Cl2.

The organic layer was dried over MgSO4 and the solvent was evaporated under reduced pressure. The

crude product was purified by silica gel chromatography (hexane–methylene dichloride, gradient from

10:1 to 3:1). Obtained blue viscous liquid. (2.56 g, 70%). 1H-NMR (CDCl3, 300 MHz): δ/ppm: 6.88

(s, 2H), 3.79-3.74 (m, 4H), 1.73-1.69 (m, 4H), 1.39-1.22 (bm, 98H), 0.91-0.87 (m, 12H). 13C-NMR

(CDCl3,300 MHz): δ/ppm: 177.89, 170.53, 153.65, 137.93, 114.40, 48.05, 36.95, 33.60, 31.95, 30.17,

29.74, 29.69, 29.54, 29.39, 26.85, 26.68, 22.72, 22.67, 14.16. TOF MS ES+(m/e): 1242.72 (M+, 100%).

Synthesis of PTIID-TVT.

The polymer was prepared using a palladium-catalyzed Stille coupling reaction. Monomer (TTIDBr)

(0.400 g, 0.3211 mmol) and (E)-1,2-bis(5-(trimethylstannyl)thiophen-2-yl)ethene (0.166 g, 0.3211

mmol) were dissolved in dry chlorobenzene (6.2 mL). After degassing under nitrogen for 60 min,

Pd2(dba)3 (5.40 mg) and P(o-Tol)3 (7.18 mg) were added to the mixture, which was then stirred for 48

h at 110°C. 2-Bromothiophene and tributyl(thiophen-2-yl)stannane were injected sequentially into the

reaction mixture for end-capping, and the solution was stirred for 6 h after each addition. The polymer

was precipitated in methanol. The crude polymer was collected by filtration and purified by Soxhlet

extraction with methanol, acetone, hexane, toluene, and chloroform, successively. The PTTID-TVT

was obtained by precipitation in methanol. Yield: 50 %. (Mn = 23,000, Mw = 42,340, PDI = 1.84). 1H

-NMR (CDCl3, 500MHz), δ (ppm): δ 7.66-7.28 (broad, 4H), 7.12-6.62 (broad, 4H), 4.02 (broad, 4 H),

1.80-1.15 (broad, 102 H), 0.90-0.85 (broad, 12H). Element Anal. Cal: C, 70.18; H, 10.09; N, 2.19;

S, 10.03. Found: C, 72.54; H, 9.44; N, 2.12; S, 8.19.

Synthesis of PTIID-TAT.

The polymer was prepared using a palladium-catalyzed Stille coupling reaction. Monomer (TIIDBr)

(0.400 g, 0.3211 mmol) and 1,2-bis(5-(trimethylstannyl)thiophen-2-yl)ethyne (0.165 g, 0.3211 mmol)

were dissolved in dry toluene (18 mL) and DMF (3.6 mL). After degassing under nitrogen for 60 min,

Tetrakis(triphenylphosphine)palladium(0) (Pd(pph3)4 (29 mg) was added to the mixture and was stirred

for 10 h at 90°C. 2-Bromothiophene and tributyl(thiophen-2-yl)stannane were injected sequentially

into the reaction mixture for end-capping, and the solution was stirred for 6 h after each addition. The

polymer was precipitated in methanol. The crude polymer was collected by filtration and purified by

Soxhlet extraction with methanol, acetone, hexane, toluene, and chloroform, successively. The TIID-

TAT was obtained by precipitation in methanol. Yield: 63 %. (Mn = 33,020, Mw = 55,140, PDI = 1.67).

1H -NMR (CDCl3, 500MHz), δ (ppm): δ 7.66-7.30 (broad, 4H), 7.13-7.04 (broad, 2H), 4.05 (broad, 4

H), 1.80-1.12 (broad, 102 H), 0.93-0.84 (broad, 12H). Element Anal. Cal: C, 75.29; H, 9.95; N,

2.20; S, 10.05. Found: C, 73.30; H, 9.58; N, 2.12; S, 9.92.

Synthesis of PTIID-TCNT.

The polymer was prepared using a palladium-catalyzed Stille coupling reaction. Monomer (TIIDBr)

(0.400 g, 0.3211 mmol) and (E)-2,3-bis(5-(trimethylstannyl)thiophen-2-yl)acrylonitrile (0.174 g,

0.3211 mmol) were dissolved in dry chlorobenzene (6.2 mL). After degassing under nitrogen for 60

min, Pd2(dba)3 (5.40 mg) and P(o-Tol)3 (7.18 mg) were added to the mixture, which was then stirred

for 48 h at 110°C. 2-Bromothiophene and tributyl(thiophen-2-yl)stannane were injected sequentially

into the reaction mixture for end-capping, and the solution was stirred for 6 h after each addition. The

polymer was precipitated in methanol. The crude polymer was collected by filtration and purified by

Soxhlet extraction with methanol, acetone, hexane, toluene, and chloroform, successively. The PTIID-

TCNT was obtained by precipitation in methanol. Yield: 49 %. (Mn = 38,020, Mw = 87,440, PDI =

1.87). 1H -NMR (CDCl3, 500MHz), δ (ppm): δ 7.79-7.24 (broad, 4H), 7.14-6.62 (broad, 3H), 4.01

(broad, 4 H), 1.80-1.13 (broad, 102 H), 0.92-0.85 (broad, 12H). Element Anal. Cal: C, 74.65; H, 9.

82; N, 3.22; S, 9.84. Found: C, 74.03; H, 9.73; N, 3.21; S, 9.79.

Characterization.

1H-NMR and 13C-NMR spectra were recorded with a Bruker Advance-300 spectrometer. The thermal

analysis was performed on a TA TGA 2100 thermogravimetric analyzer in a nitrogen atmosphere at a

rate of 10°C/min. Differential scanning calorimeter (DSC) was conducted under nitrogen on a TA

instrument 2100 DSC. The sample was heated with 10°C min-1 from 30 to 300°C. UV–vis absorption

spectra were measured by UV-1650PC spectrophotometer. Molecular weights and polydispersities of

the copolymers were determined by gel permeation chromatography (GPC) analysis with polystyrene

standard calibration (waters high-pressure GPC assembly Model M515 pump, u-Styragel columns of

HR4, HR4E, HR5E, with 500 and 100 Å , refractive index detectors, solvent THF). Cyclic

voltammetry (CV) was performed on an EG and G Parc model 273 Å potentiostat/galvanostat system

with a three-electrode cell in a solution of 0.1 M tetrabutylammonium perchlorate (Bu4NClO4) in

acetonitrile at a scan rate of 50 mV/s. A Pt wire was used as the counter electrode, and an Ag/AgNO3

(0.1 M) electrode was used as the reference electrode. The morphologies of the polymer thin films

were analyzed with a Veeco NanoScope IIIa atomic force microscope. Their molecular ordering was

analyzed by using 2D grazing incidence X-ray diffraction (2D-GIXD) at the 3C beamline of Pohang

Acceleration Laboratory. All OFETs were characterized with a Keithley 2636A SourceMeter in

vacuum (10-3 or 10-6 torr). 10-15 devices per each polymer FETs were measured. DFT calculations

were performed using Gaussian 09W with the nonlocal hybrid Becke three-parameter Lee-Yang-Parr

(B3LYP) function and the 6-31G basis set to elucidate the HOMO and LUMO levels after optimizing

the geometry of PTIID-series copolymers using the same method.

Device Fabrication.

A highly doped n-Si wafer with a 300 nm-thick thermally grown SiO2 layer was used as a substrate. A

40-45 nm-thick Cytop (Asahi Glass) was spin-coated onto it and then the film was annealed at 180°C

for 10 min, hence Cytop/SiO2 double layers work as the gate-dielectric whose capacitance is 8.1 nF

cm-2 at 1 MHz. Next, a warm chloroform solutions (5 mg mL-1 at 55°C) containing the synthesized

copolymers were dropped onto the substrate and spin-coated in a N2-purged glove box. The substrates

were also heated before spin-coating at 60°C. The films were post-annealed at a setting temperature

for 10 min in N2 environment. A thermally deposited 50 nm-thick Au layer was used as source-drain

electrodes.

Figure S1. 1H NMR spectrum of Compound 1

Figure S2. 1H NMR spectrum of Compound 2

 

Figure S3. 13C NMR spectrum of Compound 2

Figure S4. 1H NMR spectrum of Compound 3

 

Figure S5. 13C NMR spectrum of Compound 3

Figure S6. 1H NMR spectrum of TIIDBr

Figure S7. 13C NMR spectrum of TIIDBr

Figure S8. 1H NMR spectrum of PTIID-TVT

Figure S9. 1H NMR spectrum of PTIID-TAT

Figure S10. 1H NMR spectrum of PTIID-TCNT

Figure S11. Differential scanning calorimetry results of PTIID–TVT, PTIID–TAT and PTIID–TCNT.

Figure S12. Thermogravimetric analysis plot for TIID-based Polymers.

Figure S13. Shift of the internal potential energy (ΔE) of TIID–TVT, TIID–TAT, and TIID–TCNT as

a function of the dihedral angle (ϕ) of T–V, T–A, or T–CN bond.

100 200 300 400 500 600 700 800

0

20

40

60

80

100

PTIID-TVT PTIID-TAT PTIID-TCNT

Temperature (°C)

Wei

ght (

%)

-60 -40 -20 0 20 40 60

1

10

100

TIID-TVT TIID-TAT TIID-TCNT

Twist angle, ϕ (°)

ΔE

(eV

)

Figure S14. Atomic Force Microscopy (AFM) topographic images of the synthesized copolymer thin-

films: (a) PTIID–TVT, (b) PTIID–TAT, and (c) PTIID–TCNT. The scale bar is 500 nm and root-mean-

square (rms) roughness is shown in the Figures.

Table S1. Result of element analysis of the polymers.

[%]

Sample name Type Weight [mg] N C H S

bypass By-Pass 0 0 0 0

blank Blank 0 0 0 0

s1 STD 1.109 6.5400 72.5900 6.0600 7.4300

s2 STD 1.332 6.5400 72.5900 6.0600 7.4300

s3 STD 1.629 6.5400 72.5900 6.0600 7.4300

test UNK 1.320 6.5514 72.6075 6.1067 7.4017

PTIID–TVT UNK 1.463 2.1239 72.5461 9.4473 8.1933

PTIID–TAT UNK 1.360 2.1299 73.3007 9.5854 9.9270

PTIID–TCNT UNK 1.255 3.2129 74.0302 9.7361 9.7962