Supplementary Information

Synthesis of thienoselenadiazole-containing conjugated copolymers and their application in polymer solar cells

Xingxing Shen1,2, Shan Chen2, Zuo Xiao2, Qiqun Zuo3, Yiwang Chen1 and Liming Ding 2

1Institute of Polymers, Nanchang University, Xuefu Road 999, Nanchang 330031, China

2National Center for Nanoscience and Technology, No.11 Beiyitiao, Zhongguancun, Beijing 100190, China

3Jiahong Optoelectronics, Suzhou 215151, China

Correspondence: Dr L Ding, National Center for Nanoscience and Technology, No.11 Beiyitiao, Zhongguancun, Beijing 100190, China. E-mail: ; Dr Y Chen, Institute of Polymers, Nanchang University, Xuefu Road 999, Nanchang 330031, China. E-mail:

Synthesis

4,4′′-Dihexyl-3′,4′-dinitro-2,2′:5′,2′′-terthiophene (2).1 Compound 1 (1.7 g, 5.12 mmol), 3-hexyl-5-tributylstannyl-thiophene (6.4 g, 14.0 mmol), and THF (40 mL) were added to a 100 mL two-neck round-bottom flask. The solution was flushed with N2 for 20 min, and then Pd(PPh3)4 (58 mg, 0.05 mmol) was added. After flushing with N2 for 20 min, the reactant was heated to reflux for 16 h. The reactant was cooled to room temperature, and the solvent was removed by rotary evaporation. The residue was purified by silica gel column chromatography with hexane/ethyl acetate (2:1) as the eluent. Recrystallization from hexane afforded pure product 2 as an orange solid (1.9 g, yield: 73%). 1H NMR (CDCl3, 400 MHz), d (ppm): 7.39 (d, 2H), 7.21 (d, 2H), 2.61-2.71 (m, 4H), 1.61-1.72 (m, 4H), 1.27-1.45 (m, 12H), 0.88-0.99 (m, 6H). 13C NMR (CDCl3, 100 MHz), d (ppm): 144.97, 135.52, 133.99, 132.28, 127.80, 126.06, 31.60, 30.31, 30.28, 28.89, 22.58, 14.07.

4,4′′-Dihexyl-3′,4′-diamino-2,2′:5′,2′′-terthiophene (3).1 Compound 2 (2.02 g, 3.99 mmol) was suspended in ethanol (29 mL) and concentrated HCl (29 mL). To the mixture was added a solution of SnCl2 (22 g, 97.5 mmol) in EtOH (15 mL). The mixture was stirred at 30 ℃ for 30 h and poured into a cold 25% NaOH solution (100 mL). Toluene (50 mL) was added to the mixture, and the solid was removed by filtration. After separation of the toluene layer, the aqueous layer was further extracted with toluene several times. The combined organic layer was washed with brine and dried over Na2SO4. After removal of the solvent, the residue was purified by silica gel column chromatography with hexane/ethyl acetate (4:1) as the eluent. The product was obtained as a dark solid (1.2 g, yield: 67%). 1H NMR (CDCl3, 400 MHz), d (ppm): 6.93 (d, 2H), 6.85 (s, 2H), 3.12-3.44 (br, 4H), 2.53-2.65 (m, 4H), 1.55-1.71 (m, 4H), 1.20-1.44 (m, 12H), 0.80-0.97 (m, 6H). 13C NMR (CDCl3, 100 MHz), d (ppm): 144.02, 135.63, 133.37, 125.15, 118.46, 110.40, 31.68, 30.53, 30.37, 29.03, 22.61, 14.10.

4,6-Bis(5′-bromo-3′-hexylthiophen-2′-yl)thieno[3,4-c][1,2,5]selenadiazole (5).2 To the solution of compound 4 (0.37 g, 0.71 mmol) in acetic acid (30 mL) was added Br2 (0.5 mL, 9.6 mmol) dropwisely at room temperature. Then the reaction was heated to 40 ℃ and stirred for 36 h. The reactants were poured into Na2SO3 solution. The mixture was then extracted by dichloromethane several times. The combined organic layer was washed with water, saturated NaHCO3, and water successively and dried over MgSO4. After removal of the solvent, the crude product was purified by silica gel column chromatography with toluene as the eluent. The product 5 was obtained as a red solid (0.19 g, yield: 40%). 1H NMR (CDCl3, 400 MHz), d (ppm): 7.61 (s, 2H), 2.54-2.60 (m, 4H), 1.53-1.61 (m, 4H), 1.27 (d, 12H), 0.88 (t, 6H). 13C NMR (CDCl3, 100 MHz), d (ppm): 177.19, 162.53, 143.29, 138.97, 135.93, 122.55, 30.49, 28.51, 28.44, 27.81, 21.52, 13.04.


NMR Spectra

Figure S1. 1H NMR (top) and 13C NMR (bottom) for Compound 2


Figure S2. 1H NMR (top) and 13C NMR (bottom) for Compound 3


Figure S3. 1H NMR (top) and 13C NMR (bottom) for Compound 4


Figure S4. 1H NMR (top) and 13C NMR (bottom) for Compound 5


Figure S5. 1H NMR for PBDTDTTSe (top) and PDTSDTTSe (bottom)


Mass Spectra

MALDI-TOF mass spectra for compound 4

Simulated mass spectrum for compound 4

Chemical Formula: C24H30LiN2S3Se

Exact Mass: 529.090

Molecular Weight: 528.604

m/z: 529.090 (100.0%), 527.090 (48.0%), 530.093 (26.0%), 525.092 (20.2%), 531.090 (17.8%), 526.093 (15.4%), 531.085 (13.6%), 528.094 (12.5%), 528.089 (10.3%), 529.086 (6.6%), 526.096 (5.2%), 532.093 (4.6%), 527.096 (4.0%), 532.089 (4.0%), 526.090 (3.9%), 530.089 (3.9%), 531.096 (3.2%), 527.088 (2.7%), 529.092 (2.7%), 533.086 (2.4%), 523.096 (1.8%), 530.090 (1.7%), 524.091 (1.6%), 529.097 (1.6%), 530.085 (1.2%), 528.090 (1.2%), 527.093 (1.1%), 531.092 (1.0%).


References

1．  Kitamura, C., Tanaka, S. Yamashita Y. Design of Narrow-Bandgap Polymers. Syntheses and Properties of Monomers and Polymers Containing Aromatic-Donor and o-Quinoid-Acceptor Units. Chem. Mater. 8, 570-578 (1996).

2．  He, M. Q. Zhang, F. X. Synthesis and Structure of Alkyl-Substituted Fused Thiophenes Containing up to Seven Rings. J. Org. Chem. 72, 442-451 (2007).

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