SUPPORTING INFORMATION. Thermally reactive Thiazolo[5,4-d]thiazole based copolymers for high photochemical stability in polymer solar cells

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1 UPPRTING INFRMATIN Thermally reactive Thiazolo[,4-d]thiazole based copolymers for high photochemical stability in polymer solar cells Martin Helgesen *, Morten V. Madsen, Birgitta Andreasen, Thomas Tromholt, Jens W. Andreasen and Frederik C. Krebs a Risø National Laboratory for ustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4 Roskilde, Denmark. manp@risoe.dtu.dk Table of Contents: General experimental details ynthetic procedures and characterization data 2 3- H-NMR and 3 C-NMR spectra of 4 and 6-7 GIWAX data 8-

2 General experimental details General methods, instrumentation and materials. Molecular weights were determined using size exclusion chromatography in HPLC-grade chloroform against polystyrene standards on a KNAUER chromatograph with a refractive index detector and a diode array UV-vis detector. UV-vis absorption spectra were measured with a Perkin-Elmer Lambda 9 spectrometer Atomic Force Microscopy (AFM) imaging was performed on a N8 NE (Bruker Nano GmbH, Herzogenrath, Germany) operating in an intermittent contact mode using PPP-NCLR cantilevers (NANENR, Neuchatel, witzerland). Images were recorded at a scan speed of line s. Grazing Incidence Wide Angle X-ray cattering (GIWAX) patterns were obtained from polymer/pcbm thin films, deposited by spin coating a :2 blend of the polymer (PhxDT-DTZ or PehDT-DTZ) and PCBM dissolved in,2-dichlorobenzene on a silicon wafer substrate, using the custom designed GIWAX setup described by Apitz et al. By orienting the substrate surface at or just below the critical angle for total reflection with respect to the incoming X-ray beam (~.2 ), scattering from the deposited film is maximized with respect to scattering from the substrate. Unless stated otherwise all reagents and solvents were obtained from Aldrich and used without further purification. Dichloromethane, THF and toluene were dried with molecular sieves (3 Å) and used directly without filtration or distillation. NB was recrystallized from water and dried at 7 C in vacuum. Evaporation was performed on a rotary evaporator at 4 C. NMR spectra were obtained on a Bruker 2 MHz or MHz spectrometer. 3-methyl-3-octyl thiophene-3-carboxylate (2), 4,4-dihexyl- 2,6-bis(trimethylstannyl)-4H-silolo[3,2-b:4,-b']dithiophene and 4,4-bis(2-ethylhexyl)-2,6- bis(trimethylstannyl)-4h-silolo[3,2-b:4,-b']dithiophene were prepared according to literature procedures 2,3 or slight modifications thereof. Apitz, D.; Bertram, R.P.; Benter, N.; Hieringer, W.; Andreasen, J.W.; Nielsen, M.M.; Johansen, P.M.; Buse, K. Phys. Rev. 2, E 72, Usta, H.; Lu, G.; Facchetti, A.; Marks, T. J. J.Am.Chem.oc. 26, 28, Helgesen, M.; Bjerring, M.; Nielsen, N. C.; Krebs, F. C. Chem. Mater. 2, 22,

3 ynthetic procedures and characterization data cheme. ynthetic steps involved in the preparation of the polymers 3-methyl-3-octyl thiophene-3-carboxylate (2): A mixture of thiophene-3-carboxylic acid () ( g, 39 mmol), DMAP (.2 g, 43 mmol) and 3-methyl-3-octanol (7. ml, 43 mmol) in dry methylene chloride ( ml) was stirred at room temperature under argon for min. N,N -diisopropylcarbodiimide (6.7 ml, 43 mmol) was added and the reaction mixture was heated to 4 C and stirred for 24 hours. After cooling to room temperature the reaction mixture was concentrated on celite in vacuum. Dry column chromatography (silica gel -4 μm, eluted with EtAc/heptane, gradient -3% EtAc) afforded 2. Yield: 7. g (72 %), colourless oil. H NMR (2 MHz, CDCl 3 ) δ = 8. (dd, J = 3. Hz, J =. Hz, H), 7.46 (dd, J =. Hz, J =. Hz, H), 7.26 (dd, J =. Hz, J = 3. Hz, H), (m, 4H),. (s, 3H), (m, 6H), (m, 6H). 3 C NMR ( MHz, CDCl 3 ) δ = 6.93, 3.68, 3.78, 27.96, 2.6, 8.89, 38., 32.8, 3.3, 23.43, 23.33, 22.6, 4.,

4 3-methyl-3-octyl 2-formylthiophene-3-carboxylate (3): ml dry THF was cooled to - C under argon followed by addition of ml n-butyllithium (.6 M in hexane). Then a solution of 2.4 ml diisopropylamine and 7.6 ml dry THF was added slowly and the reaction mixture was stirred for 3 min. 26 ml (3 mmol) of the freshly prepared solution of lithium diisopropylamine was added slowly to a cooled solution (-78 C) of 2 (3 g, 2 mmol) in dry THF (3 ml). The reaction mixture was stirred for hour at -78 C under argon followed by addition of N-formylpiperidine (NFP, 3.9 ml, 3 mmol). The reaction mixture was allowed to warm to room temperature over 2 hours. Water was added to the reaction mixture followed by extraction with ether. The combined organic phase was dried over magnesium sulfate, filtered and concentrated in vacuum. Dry column chromatography (silica gel -4 μm, eluted with EtAc/heptane, gradient -% EtAc) afforded 3. Yield: 2.6 g (78 %), light yellow oil. H NMR ( MHz, CDCl 3 ) δ.6 (d, J =.2 Hz, H), 7.63 (dd, J =. Hz,.2 Hz, H), 7.4 (d, J =. Hz, H), (m, 4H),.7 (s, 3H),.4.27 (m, 6H), (m, 6H). 3 C NMR ( MHz, CDCl 3 ) δ = 84.93, 6., 46.77, 38.76, 32.44, 3.2, 88.22, 37.88, 32., 3., 23.49, 23.39, 22.4, 4., 8.3. bis(3-methyl-3-octyl) 2,2'-(thiazolo[,4-d]thiazole-2,-diyl)bis(thiophene-3-carboxylate) (4): A solution of 3 (2.9 g, mmol) and dithiooxamide (68 mg, 4.7 mmol) in N,N-dimethylformamide (2 ml) was heated to 2 C for h and then cooled down to room temperature. The reaction mixture was poured into water and extracted with dichloromethane. The combined organic phase was dried over magnesium sulfate, filtered and concentrated in vacuum. Dry column chromatography (silica gel -4 μm, eluted with toluene/heptane, gradient -% toluene) followed by recrystallization from ethanol afforded 4 as a dark orange solid. Yield: 964 mg (32 %). M p = -2 C. H NMR ( MHz, CDCl 3 ) δ = 7.47 (d, J =.4 Hz, 2H), 7.38 (d, J =.4 Hz, 2H), 2..8 (m, 8H),.7 (s, 6H),.4.26 (m, 2H), (m, 2H). 3 C NMR ( MHz, CDCl 3 ) δ = 62.36, 6.47, 3.3, 43.7, 3.8, 3.8, 27.4, 87.44, 37.9, 32.7, 3.6, 23.44, 23.38, 22.8, 4.4, 8.7. HRM-E+: m/z calcd for C 32 H 43 N [M + H] +, ; found,

5 bis(3-methyl-3-octyl) 2,2'-(thiazolo[,4-d]thiazole-2,-diyl)bis(-bromothiophene-3-carboxylate) (): To a solution of 4 (9 mg,.4 mmol) in 4 ml THF/DMF (2:) was added NB (4 mg, 3. mmol) and one drop acetic acid. The resulting mixture was then stirred at room temperature for 48 hours. During this period the reaction was monitored by TLC and additional portions of NB ( x 7 mg) were added until the conversion was complete. The mixture was poured into brine and extracted several times with dichloromethane. The combined organic phase was dried (Mg 4 ), filtered and concentrated in vacuum. Dry column chromatography (silica gel -4 μm, eluted with toluene/heptane, gradient -% toluene) afforded as an orange solid. Yield: 882 mg (79 %). M p = C. H NMR ( MHz, CDCl 3 ) δ = 7.39 (s, 2H), (m, 8H),.7 (s, 6H), (m, 2H), (m, 2H). 3 C NMR ( MHz, CDCl 3 ) δ = 6.2, 9., 3.46, 4., 32.8, 3.6,.37, 88.6, 37.86, 32.4, 3.3, 23.44, 23.38, 22.6, 4.3, 8.8. M-E+: m/z calcd for C 32 H 4 Br 2 N [M + H] +, 83.3; found, PhxDT-DTZ: (2 mg,.2 mmol), 4,4-dihexyl-2,6-bis(trimethylstannyl)-4H-silolo[3,2-b:4,- b']dithiophene (7 mg,.2 mmol), Pd 2 dba 3 ( mg,.2 mmol) and tri-(o-tolyl)phosphine (9 mg, 62 mmol) was mixed in dry degassed toluene (6 ml). The reaction mixture was heated to reflux for 48 hours under argon. After cooling to room temperature the mixture was poured into ml methanol and the polymer was allowed to precipitate. The polymer was filtered and purified by oxhlet extraction using methanol, hexane and chloroform. The chloroform phase was concentrated to a smaller volume in vacuum and precipitated in methanol (:). Filtration and drying in vacuum afforded PhxDT-DTZ as a dark blue solid. Yield: 237 mg (9 %). H NMR ( MHz, CDCl 3 ) δ = (br, 4H), (br, 64H). EC (CHCl 3 ): M w = 324, M n = 9, PDI = 3.4. PehDT-DTZ: Prepared with the same procedure as for PhxDT-DTZ using the monomers and 4,4- bis(2-ethylhexyl)-2,6-bis(trimethylstannyl)-4h-silolo[3,2-b:4,-b']dithiophene. Yield: 87 mg (7 %), dark blue solid. H NMR ( MHz, CDCl 3 ) δ = 7.44 (br s, H), 7.8 (s, H), 6.9 (s, 2H), (m, 72H). EC (CHCl 3 ): M w = 38, M n = 4, PDI = 2.2

6 Figure. H-NMR pectrum of 4 in CDCl 3 C H N N 4 C H ppm Figure 2. 3 C-NMR pectrum of 4 in CDCl ppm

7 Figure 3. H-NMR pectrum of in CDCl 3 C H N Br Br N C H ppm Figure 4. 3 C-NMR pectrum of in CDCl ppm

8 GIWAX data PhxDT-DTZ/PCBM thin film Gaussian fit: Centre =.374 Amplitude = igma =.383 (FWHM =.8968) ffset = lope = Qz 2 Qxy

9 PhxDT-DTZ*/PCBM thin film Gaussian fit: Centre =.36 Amplitude = 9.87 igma =.3222 (FWHM =.783) ffset = lope = Qz. Qxy

10 PehDT-DTZ/PCBM thin film Gaussian fit: Centre = Amplitude = 2.69 igma =.892 (FWHM =.9) ffset = lope = Qz. Qxy

11 PehDT-DTZ*/PCBM thin film 6 Qz 3 Qxy X:.7233 Y: