Supporting Information. An Easily Accessible Isoindigo-Based Polymer for High-Performance Polymer Solar Cells

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1 upporting Information An Easily Accessible Isoindigo-Based Polymer for High-Performance Polymer olar Cells Ergang Wang,*, Zaifei Ma, Zhen Zhang,, Koen Vandewal, Patrik Henriksson, Olle Inganäs, Fengling Zhang, and Mats R. Andersson*, Department of Chemical and Biological Engineering/Polymer Technology, Chalmers University of Technology, E Göteborg, weden Biomolecular and Organic Electronics, IFM, Linköping University, E Linköping, weden Key Laboratory for Ultrafine Materials of Ministry of Education, chool of Materials cience and Engineering, East China University of cience and Technology, Mei Long Road130, hanghai , China To whom correspondence should be addressed. Table of Contents Characterization...2 Figure 1. The photoluminescence spectra of P3TI and their blends with PC 71 BM....2 Electrochemical studies...2 Figure 2. WV of the thin films of P3TI and PC 71 BM...3 olar cells fabrication and characterization:...3 ynthetic Procedures...4 References

2 Experimental ection Characterization: 1 H NMR (400 MHz) and 13 C NMR (100 MHz) spectra were acquired from a Varian Inova 400 MHz NMR spectrometer. Tetramethylsilane was used as an internal reference with deuterated chloroform as solvent. TGA was performed on Perkin Elmer TGA7. ize exclusion chromatography (EC) was performed on Waters Alliance GPCV2000 with a refractive index detector. Columns: Waters tyvagel HT GE 1, Waters tyvagel HMW GE 2. The eluent was 1,2,4-trichlorobenzene. The working temperature was 135 C, and the resolution time was 2 h. The concentration of the samples was 0.5 mg ml 1, which were filtered (filter: 0.45 µm) prior to the analysis. The molecular weights were calculated according to relative calibration with polystyrene standards. UV-vis absorption spectra were measured with a Perkin Elmer Lambda 900 UV-Vis-NIR absorption spectrometer. The electroluminescence and the photoluminescence spectra were obtained by an Andor spectrometer (hamrock sr-303i-b, coupled to a Newton EMCCD detector). For the photoluminescence experiments the pumping light source is a red CW He- Ne 632 nm laser with an intensity of 2 mw. FTP measurements were performed by using the photovoltaic devices as external detector in a research grade Bruker vertex 70 FTIR, equipped for the visible and near IR spectral range with a quartz beamsplitter and halogen lamp. More details can be found in a previous report. 1 The surface morphology of active layers of PCs was characterized by using Atomic Force Microscopy (AFM) with a Dimension 3100 system (Digital Instruments/Veeco) operating in tapping mode. Photoluminescence P3TI:PC 71 BM=1:1.5, DCB w/o DIO 180 P3TI:PC 71 BM=1:1.5, DCB with DIO P3TI, DCB w/o DIO 60 P3TI, DCB with DIO Wavelength (nm) Figure 1. The photoluminescence spectra of P3TI and their blends with PC 71 BM. Electrochemical studies quare-wave voltammetry (WV) measurements were carried out on a CH-Instruments 650A Electrochemical Workstation. A three-electrode setup was used with platinum wires both as working electrode and counter electrode, and Ag/Ag + was used as reference electrode calibrated with ferro- 2

3 cene/ferrocenyl couple (Fc/Fc + ). A 0.1 M solution of tetrabutylammonium hexafluorophosphate (Bu 4 NPF 6 ) in anhydrous acetonitrile was used as supporting electrolyte. The polymer was deposited onto the working electrode from chloroform solution. In order to remove oxygen from the electrolyte, the system was bubbled with nitrogen prior to each experiment. The nitrogen inlet was then moved to above the liquid surface and left there during the scans. HOMO and LUMO levels were estimated from peak potentials of the third scan by setting the oxidative peak potential of Fc/Fc + vs. the normal hydrogen electrode (NHE) to 0.63 V, 2 and the NHE vs. the vacuum level to 4.5 V. 3 The HOMO and LUMO levels were calculated according to the formula HOMO = (E ox ) ev and LUMO = (E red ) ev, where E ox and E red were determined from oxidation and reduction peaks respectively. 4 Normalized Current (a.u.) P3TI PC 71 BM Potential vs. Fc/Fc + (V) Figure 2. WV of the thin films of P3TI and PC 71 BM. olar cells fabrication and characterization: The configuration of the solar cells was Glass/ITO/PEDOT:P/Active Layer/LiF/Al. As a buffer layer, the conductive polymer, PEDOT:P (Baytron P VP Al 4083), was spin-coated onto ITO-coated glass substrates at 3000 rpm for 60 s, followed by annealing at 120 C for 10 min to remove water. The glass substrates were cleaned by detergent and acetone first, and then by TL1 (NH 3 :H 2 O 2 :H 2 O = 1:1:5) procedure for 10 min before use. The thickness of the PEDOT:P layer was ~40 nm, as determined by a Dektak 6M surface profilometer. The active layer consisting of polymer and PC 71 BM was spin-coated from DCB solution (or with DIO additive) onto the PEDOT:P layer. The spin-coating was done in a glove box and the material was directly transferred to a vapor deposition system mounted inside the glove box. LiF (0.6 nm) and Al (80 nm) were used as top electrodes and were deposited via a shadow mask in vacuum (below mbar) onto the active layer. The accurate area of every device (4 6 mm 2 ), defined by the overlap of the ITO and metal electrode, was measured carefully by optical microscope. EQEs were calculated from the photocurrents at short-circuit conditions. The currents were recorded by a Keithley 485 Picoammeter, under illumination of monochromatic light (M257) through the ITO side of the devices. PCE was calculated from J V characteristics recorded by a Keithley

4 source meter under illumination of an AM1.5G solar simulator with an intensity of 100 mw cm 2 (Model -50A, Photo Emission Tech., Inc.). The light intensity was determined by a standard silicon photodiode calibrated in ECN (Energy research Center of the Netherlands). ynthetic Procedures: All reagents and starting materials were purchased from Aldrich and used without further purification, unless otherwise noted. 6-Bromoisatin and 6-bromooxindole were obtained from Puyang Huicheng Chemical Co. Ltd. 2,5-Bis(trimethylstannyl)thiophene was purchased from olarmer Energy Inc. 6,6'- Dibromoisoindigo, tributyl(4-octylthiophen-2-yl)stannane and 1-bromo-2-hexyldecane were prepared according to the literature methods. 5-7 ynthesis of (E)-6,6'-dibromo-1,1'-bis(2-hexyldecyl)-[3,3'-biindolinylidene]-2,2'- dione (1) 8 1-Bromo-2-hexyldecane (3.36 g, 11 mmol) was added to a suspension of 6,6'-dibromoisoindigo (2.10 g, 5 mmol) and potassium carbonate (6.90 g, 50 mmol) in dimethylformamide (DMF) (100 ml). The mixture was heated to 100 C for 24 h. After cooling to room temperature, the mixture was transferred to a separatory funnel, extracted with diethyl ether and then washed with water. The ether phase was dried over MgO 4. Removal of the solvent gave a crude product, which was purified by silica-gel column chromatography using a mixture of hexane:dichloromethane (1:1) as eluent to obtain compound 1 (3.51 g, 80.8%). 1 H NMR (400 MHz, CDCl 3, δ): 9.09 (d, J = 8.6 Hz, 2H), 7.16 (dd, J = 8.6 Hz, J = 1.9 Hz, 2H), 6.91 (d, J = 1.8 Hz, 2H), 3.64 (d, J = 7.5 Hz, 4H), (m, 2H), (m, 48 H), (m, 12H). 13 C NMR (100 MHz, CDCl 3, δ): , , , , , , , , 44.69, 36.08, 31.86, 31.80, 31.48, 29.98, 29.65, 29.54, 29.29, 26.35, 26.32, 22.67, 22.64, 14.12, (E)-1,1'-bis(2-hexyldecyl)-6,6'-bis(4-octylthiophen-2-yl)-[3,3'-biindolinylidene]-2,2'-dione (2) 4

5 C H 6 13 C 6 H 13 Br N O Br nbu 3 N O O N Pd 2 (dba) 3 P(o-tol) 3 THF O N C 6 H 13 1 C 6 H 13 2 To the solution of compound 1 (4.15 g, 4.78 mmol) and tributyl(4-octylthiophen-2-yl)stannane (5.80 g, mmol) in anhydrous tetrahydrofuran (THF, 50 ml) bubbled with nitrogen, tris(dibenzylideneacetone)dipalladium(0) (Pd 2 (dba) 3 ) (15 mg) and tri(o-tolyl)phosphine (P(o-tol) 3 ) (30 mg) were added in one portion. The solution was bubbled with nitrogen for another 20 min. The mixture was stirred overnight at 80 C under nitrogen. Then the mixture was cooled to room temperature and poured into water. The organic phase was extracted by diethyl ether, and then washed with water, dried over MgO 4. After the removal of the solvent under reduced pressure, the solids were purified by silica chromatography with dichloromethane: hexane = 1: 2 as the eluent to afford the compound 2 (4.34 g, 82.5%). 1 H NMR (400 MHz, CDCl 3 ): δ (ppm) 9.15 (d, J = 8.4 Hz, 2H), 7.24 (m, 4H), 6.95 (m, 4H), 3.69 (d, J = 7.0 Hz, 4H), 2.63 (t, J = 7.4 Hz, 4H), 1.91 (b, 2H), 1.66 (m, 4H), (m, 68H), (m, 18H). 13 C NMR (100 MHz, CDCl 3, δ): , , , , , , , , , , 44.40, 36.39, 31.88, 31.85, 31.77, 30.62, 30.46, 29.99, 29.66, 29.59, 29.44, 29.38, 29.36, 29.29, 29.28, 28.26, 26.76, 26.64, 22.66, 22.63, 17.27, 14.09, (E)-6,6'-bis(5-bromo-4-octylthiophen-2-yl)-1,1'-bis(2-hexyldecyl)-[3,3'-biindolinylidene]-2,2'-dione (3) C H 6 13 C 6 H 13 N O NB, THF Br N O Br O N O N C 6 H 13 C 6 H To the solution of the compound 2 (2.20 g, 2.00 mmol) in fresh distilled THF (60 ml), N- bromosuccinimide (NB) (0.748 g, 4.2 mmol) was added in several portions in 2 h at room temperature. After the addition of NB, the mixture was stirred for another 2 h, and then poured into water. The or- 5

6 ganic phase was extracted by diethyl ether, washed by water, dried over MgO 4. After the purification by silica chromatography with hexane: dichloromethane = 2: 1 as the eluent, compound 3 was obtained (2.19 g, 87.1%). 1 H NMR (400 MHz, CDCl 3 ): δ (ppm) 9.15 (d, J = 8.3 Hz, 2H), 7.17 (d, J = 7.9 Hz, 2H), 7.09 (s, 2H), 6.85 (s, 2H), 3.68 (d, J = 6.4 Hz, 4H), 2.58 (t, 4H), 1.91 (s, 2H), 1.63 (s, 4H), (m, 68H), (m, 18H). 13 C NMR (100 MHz, CDCl 3 ): δ (ppm) , , , , , , , , , , 52.13, 44.33, 36.37, 31.88, 31.76, 30.03, 30.00, 29.77, 29.73, 29.67, 29.61, 29.40, 29.33, 29.28, 29.25, 26.66, 26.62, 22.67, 20.52, ynthesis of P3TI In a 25 ml dry flask, 2,5-bis(trimethylstannyl)thiophene (82 mg, 0.2 mmol), 3 (251 mg, 0.2 mmol), tris(dibenzylideneacetone)dipalladium(0) (Pd 2 (dba) 3 ) (6 mg) and tri(o-tolyl)phosphine (P(o-Tol) 3 ) (10 mg) were dissolved in degassed toluene (6 ml). The mixture was vigorously stirred at 100 C under nitrogen (reaction time: 24 h for high molecular weight batch, 2 h for low molecular weight batch). After cooling to r. t., the solution was poured into acetone. The polymer was collected by filtration through 0.45 μm Teflon filter. And then the polymer was washed in a oxhlet extractor with acetone and diethyl ether for 24 h each. After that, the polymer was oxhlet-extracted with chloroform. The chloroform fraction was purified by passing it though a short silica gel column and then precipitated from acetone. Finally, the polymer was collected by filtration through 0.45 μm Teflon filter and dried under vacuum at 40 C overnight (200 mg, 84.9%). References: (1) Vandewal, K.; Tvingstedt, K.; Gadisa, A.; Inganas, O.; Manca, J. V. Nat. Mater. 2009, 8, 904. (2) Pavlishchuk, V. V.; Addison, A. W. Inorg. Chim. Acta. 2000, 298, 97. (3) A. J. Bard; L. R. Faulkner Electrochemical methods: fundamentals and applications; 2nd ed.; Wiley: New York, (4) Hellström,.; Zhang, F. L.; Inganäs, O.; Andersson, M. R. Dalton Trans. 2009, (5) Mei, J.; Graham, K. R.; talder, R.; Reynolds, J. R. Org. Lett. 2010, 12, 660. (6) Burgi, L.; Turbiez, M.; Pfeiffer, R.; Bienewald, F.; Kirner, H. J.; Winnewisser, C. Adv. Mater. 2008, 20, (7) Cai, T.; Zhou, Y.; Wang, E.; Hellström,.; Zhang, F.; Xu,.; Inganäs, O.; Andersson, M. R. ol. Energy Mater. ol. Cells 2010, 94, (8) Wang, E. G.; Ma, Z. F.; Zhang, Z.; Henriksson, P.; Inganas, O.; Zhang, F. L.; Andersson, M. R. Chem. Commun. 2011, 47,

7 Figure 3. 1 H NMR spectrum of (E)-6,6'-dibromo-1,1'-bis(2-hexyldecyl)-[3,3'-biindolinylidene]- 2,2'- dione (1) 7

8 Figure C NMR spectrum of (E)-6,6'-dibromo-1,1'-bis(2-hexyldecyl)-[3,3'-biindolinylidene]- 2,2'- dione (1). (To see it clearly, it was divided into two parts.) 8

9 f1 (ppm) Figure 5. 1 H NMR spectrum of (E)-1,1'-bis(2-hexyldecyl)-6,6'-bis(4-octylthiophen-2-yl)-[3,3'- biindolinylidene]-2,2'-dione (2)

10 f1 (ppm) Figure C NMR spectrum of (E)-1,1'-bis(2-hexyldecyl)-6,6'-bis(4-octylthiophen-2-yl)-[3,3'- biindolinylidene]-2,2'-dione (2). 10

11 Figure 7. 1 H NMR spectrum of (E)-6,6'-bis(5-bromo-4-octylthiophen-2-yl)-1,1'-bis(2-hexyldecyl)- [3,3'-biindolinylidene]-2,2'-dione (3) 11

12 f1 (ppm) Figure C NMR spectrum of (E)-6,6'-bis(5-bromo-4-octylthiophen-2-yl)-1,1'-bis(2-hexyldecyl)- [3,3'-biindolinylidene]-2,2'-dione (3) 12