DOI: 10.1038/NMAT3160 Supporting Information · molecular sieves (4 Å). Chloroform was dried over calcium hydride, distilled under vacuum, and stored over molecular sieves (4 Å)

1

Supporting Information

Solution-Processed Small-Molecule Solar Cells with 6.7%

Efficiency

Yanming Sun, Gregory C. Welch, Wei Lin Leong, Christopher J. Takacs,

Guillermo C. Bazan* and Alan J. Heeger*

Center for Energy Efficient Materials, Center for Polymers and Organic Solids, Departments of

Physics and Chemistry & Biochemistry, University of California, Santa Barbara, California 93106

*email: [email protected]; [email protected]

Materials and methods S2-4 Synthesis and characterization S4-8 NMR spectra of DTS(PTTh2)2 and 1 S9-12 UV-visible absorption spectra of 1 S13 Single crystal X-ray structure of 1 S14 Differential scanning calorimetry of DTS(PTTh2)2 S15 Cyclic voltammetry of DTS(PTTh2)2 S15 UV-visible absorption spectra of DTS(PTTh2)2 S16 OFET data S17 OPV data S18-19 TEM image processing S20-25 References S25-26

SUPPLEMENTARY INFORMATIONDOI: 10.1038/NMAT3160

NATURE MATERIALS | www.nature.com/naturematerials 1

© 2011 Macmillan Publishers Limited. All rights reserved.

http://www.nature.com/doifinder/10.1038/nmat3160

2

Materials and methods:

Preparations were carried out on a bench top or under an atmosphere of dry, O2-free N2

employing both Schlenk line techniques and an Vacuum Atmospheres inert atmosphere glove

box. Toluene was dried over sodium/benzophenone, distilled under vacuum, and stored over

molecular sieves (4 Å). Chloroform was dried over calcium hydride, distilled under vacuum, and

stored over molecular sieves (4 Å). Molecular sieves (4 Å) were purchased from Aldrich

Chemical Company and dried at 140 ºC under vacuum for 24 hours prior to use. Deuterated

solvents were dried over CaH2 (CDCl3) All reactants and reagents are commerically available

and used as recieved, unless otherwise noted. Compound 5,5’-Bis(trimethylstannyl)-3,3’-di-2-

ethylhexylsilylene-2,2’-bithiophene {DTS(SnMe3)2} and 5'-Hexyl-2,2'-bithiophene-5-

trimethylstannane were synthesized in our labs via standard procedures. Compounds 5,5’-

dibromo-3,3’-di-2- ethylhexylsilylene-2,2’-bithiophene (DTS-Br2) and 4,7-dibromo-

pyridal[2,1,3]thiadiazole (PTBr2) were purchased from Luminescence Technology Corp

(Lumtec) and used as recieved. Compound 5-Hexyl-2,2'-bithiophene was purchased from

Aldrich Chemical Company and used as recieved. PC70BM was purchased from Solenne BV and

used as recieved.

1H and 13C nuclear magnetic resonance (NMR) spectroscopy spectra were recorded on a

Bruker Avance-500 MHz spectrometer at 300K unless otherwise noted. 1H and 13C NMR spectra

are referenced to SiMe4 using the residual solvent peak impurity of the given solvent. Chemical

shifts are reported in ppm and coupling constants in Hz as absolute values. DEPT, 1H-1H, and

1H-13C correlation experiments were completed for assignment of the carbon atoms. 1H-1H NOE

experiments were carried out with a mixing time of 0.8 seconds.

3

UV-visible spectroscopy were recored using wither a Beckman Coulter DU 800 series or

Perkin Elmer Lambda 750 spectrophotometer at room temperature unless otherwise noted. All

solution UV-vis experiments were run in CHCl3 under an N2 atmosphere in telfon capped 1mm

quartz cuvettes. Neat Films were prepare by spin-coating solutions from CHCl3 onto quartz

substrates.

Combustion analyses were performed by the MSI analytical lab at the University of

California, Santa Barbara.

Differential scanning calorimetry (DSC) was determined using a TA Instruments DSC

(Model Q-20) with about 5 mg samples at a rate of 10 °C / min in the temperature range of 0 to

300 °C.

All electrochemical measurements were performed using CHI instrument model 730B in

a standard three-electrode, one compartment configuration equipped with Ag wire, Pt wire and

Glassy carbon electrode (dia. 3 mm), as the pseudo reference, counter electrode and working

electrode respectively. Glassy carbon electrodes were polished with alumina. The cyclic

voltammetry (CV) experiments were performed in anhydrous dichloromethane solution with

~0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) as the supporting electrolyte at

scan rate 50 mV/s unless otherwise stated. All electrochemical solutions were purged with dry

Ar2 for 5 minutes to deoxygenate the system. Under these conditions, a Fc/Fc+ standard was

calibrated to be ~0.218 V. Solution CV measurements were carried out with a small molecule

concentration of ~1mg/mL in CH2Cl2. The HOMO and LUMO levels were obtained by

correlating the onsets (EoxFc/Fc+, Erd

Fc/Fc+) to the normal hydrogen electrode (NHE), assuming

HOMO of Fc/Fc+ to be 4.88 eV.1

2 NATURE MATERIALS | www.nature.com/naturematerials

SUPPLEMENTARY INFORMATION DOI: 10.1038/NMAT3160



2

Materials and methods:

Preparations were carried out on a bench top or under an atmosphere of dry, O2-free N2

employing both Schlenk line techniques and an Vacuum Atmospheres inert atmosphere glove

box. Toluene was dried over sodium/benzophenone, distilled under vacuum, and stored over

molecular sieves (4 Å). Chloroform was dried over calcium hydride, distilled under vacuum, and

stored over molecular sieves (4 Å). Molecular sieves (4 Å) were purchased from Aldrich

Chemical Company and dried at 140 ºC under vacuum for 24 hours prior to use. Deuterated

solvents were dried over CaH2 (CDCl3) All reactants and reagents are commerically available

and used as recieved, unless otherwise noted. Compound 5,5’-Bis(trimethylstannyl)-3,3’-di-2-

ethylhexylsilylene-2,2’-bithiophene {DTS(SnMe3)2} and 5'-Hexyl-2,2'-bithiophene-5-

trimethylstannane were synthesized in our labs via standard procedures. Compounds 5,5’-

dibromo-3,3’-di-2- ethylhexylsilylene-2,2’-bithiophene (DTS-Br2) and 4,7-dibromo-

pyridal[2,1,3]thiadiazole (PTBr2) were purchased from Luminescence Technology Corp

(Lumtec) and used as recieved. Compound 5-Hexyl-2,2'-bithiophene was purchased from

Aldrich Chemical Company and used as recieved. PC70BM was purchased from Solenne BV and

used as recieved.

1H and 13C nuclear magnetic resonance (NMR) spectroscopy spectra were recorded on a

Bruker Avance-500 MHz spectrometer at 300K unless otherwise noted. 1H and 13C NMR spectra

are referenced to SiMe4 using the residual solvent peak impurity of the given solvent. Chemical

shifts are reported in ppm and coupling constants in Hz as absolute values. DEPT, 1H-1H, and

1H-13C correlation experiments were completed for assignment of the carbon atoms. 1H-1H NOE

experiments were carried out with a mixing time of 0.8 seconds.

3

UV-visible spectroscopy were recored using wither a Beckman Coulter DU 800 series or

Perkin Elmer Lambda 750 spectrophotometer at room temperature unless otherwise noted. All

solution UV-vis experiments were run in CHCl3 under an N2 atmosphere in telfon capped 1mm

quartz cuvettes. Neat Films were prepare by spin-coating solutions from CHCl3 onto quartz

substrates.

Combustion analyses were performed by the MSI analytical lab at the University of

California, Santa Barbara.

Differential scanning calorimetry (DSC) was determined using a TA Instruments DSC

(Model Q-20) with about 5 mg samples at a rate of 10 °C / min in the temperature range of 0 to

300 °C.

All electrochemical measurements were performed using CHI instrument model 730B in

a standard three-electrode, one compartment configuration equipped with Ag wire, Pt wire and

Glassy carbon electrode (dia. 3 mm), as the pseudo reference, counter electrode and working

electrode respectively. Glassy carbon electrodes were polished with alumina. The cyclic

voltammetry (CV) experiments were performed in anhydrous dichloromethane solution with

~0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) as the supporting electrolyte at

scan rate 50 mV/s unless otherwise stated. All electrochemical solutions were purged with dry

Ar2 for 5 minutes to deoxygenate the system. Under these conditions, a Fc/Fc+ standard was

calibrated to be ~0.218 V. Solution CV measurements were carried out with a small molecule

concentration of ~1mg/mL in CH2Cl2. The HOMO and LUMO levels were obtained by

correlating the onsets (EoxFc/Fc+, Erd

Fc/Fc+) to the normal hydrogen electrode (NHE), assuming

HOMO of Fc/Fc+ to be 4.88 eV.1





4

Single crystal of 1 was mounted on a glass fiber and transferred to a Bruker Kappa APEX

II CCD diffractometer. The APEX2 software program was used to determine the unite cell

parameters and data collection. The data were collected at 100K using Oxford Cryostream Plus

system. The raw frame data were processed using APEX2 program. The absorption correction

was applied using program SADABS. Subsequent calculations were carried out using SHELXTL

program. All non-H atoms were refined anisotropically. Carbon-bound hydrogen atoms were

placed in calculated positions using an appropriate riding model and coupled isotropic

temperature factors.

Synthesis and Characterization of DTS(PTTh2)2:

Synthesis of 5,5’-bis{(4-(7-bromo-[1,2,5]thiadiazolo[3,4-c]pyridine)}-3,3’-di-2-

ethylhexylsilylene-2,2’-bithiophene (1): In a N2 filled glove box a 20 mL microwave tube was

charged with 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine (PTBr2, 790 mg, 2.68 mmol), 5,5’-

Bis(trimethylstannyl)-3,3’-di-2-ethylhexylsilylene-2,2’-bithiophene (DTS(SnMe3)2, 800 mg, 1.07

mmol), Pd(PPh3)4 (0.025 g, 0.02 mmol), toluene (15 mL), and sealed with a Teflon® cap. Using

a Biotage microwave reactor with stirring (900 rpm), the reaction mixture was heated to 80oC for

5 minutes, 100oC for 5 minutes, 120oC for 5 minutes, 140oC for 5 minutes, and 160oC for 60

minutes. Upon cooling, the purple residue was passed through a short silica plug eluting with

CHCl3 (1% Et3N) (~500 mL). All volatiles were removed in vacuo to give the crude product as a

dark sticky solid. The material was then slurried in methanol (300 mL), filtered, loaded onto

silica using CHCl3 and purified by flash chromatography using a hexanes/CHCl3 gradient. The

silica gel was pre-treated with hexanes/Et3N (90:10). The product eluted as a purple solution at

~50% CHCl3. After fraction collection and solvent removal, the solid product was slurried in

5

methanol (300 mL), sonicated for 30 minutes, and filtered. The solid was washed with copious

amounts of methanol and acetone, and then dried under vacuum for 24 hours. The product was

collected as green metallic coloured powder. Recovered yield: 650 mg (72%). 1H NMR

(CDCl3): δ 8.76 (s, 2H, DTS-CH), 8.65 (s, 2H, PT-CH), 1.52 (m, 2H, CH),1.39 (m, 4H, CH2),

1.31 (m, 4H, CH2), 1.16 (m, 8H, CH2), 1.06 (m, 4H, CH2), 0.85 (m, 12H, CH3). 13C{1H} NMR

(CDCl3): 156.38, 153.85, 147.98, 147.66, 147.49 (s, quaternary), 146.03 (s, CH), 143.94 (s,

quaternary), 135.99 (s, CH), 107.64 (s, quaternary), 36.02 (s, CH), 35.76 (s, CH2), 22.97 (s,

CH2), 22.93 (s, CH2), 20.92 (s, CH2), 17.64 (s, CH2), 14.15 (s, CH3). 10.80 (s, CH3). Elemental

analysis calculated for C34H38Br2N6S4Si: C, 48.22; H, 4.52; N, 9.92. Found: C, 48.3; H, 4.56; N,

9.82 %. UV-Visible Absorbance: (CHCl3) λmax = 575 nm, λonset = 625 nm. (As Cast Film) λmax =

585, 625 nm, λonset = 682 nm. Single Crystal X-Ray Diffraction: Crystals grown from slow

evaporation of CHCl3. Triclinic, P-1. Cell: a = 11.7963(7) Å, b = 13.0288(8) Å, c = 13.8853(8)

Å, alpha = 98.624(2)° beta = 103.354(2)° gamma = 97.552(2)°. V = 2022.1(2) Å3. R1 = 0.0653,

wR2 = 0.1678.

Synthesis of 5,5’-bis{(4-(7-hexylthiophen-2-yl)thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-

c]pyridine}-3,3’-di-2-ethylhexylsilylene-2,2’-bithiophene (DTS(PTTh2)2): In a N2 filled glove

box, a 20 mL microwave tube was charged with 5,5’-bis{(4-(7-bromo-[1,2,5]thiadiazolo[3,4-

c]pyridine)}-3,3’-di-2-ethylhexylsilylene-2,2’-bithiophene (1, 420 mg, 0.50 mmol), 5'-hexyl-

2,2'-bithiophene-5-trimethylstannane (450 mg, 1.09 mmol), Pd(PPh3)4 (0.025 g, 0.02 mmol),

toluene (15 mL), and sealed with a Teflon® cap. Using a Biotage microwave reactor with

stirring (900 rpm), the reaction mixture was heated to 80oC for 5 minutes, 100oC for 5 minutes,

120oC for 5 minutes, 140oC for 5 minutes, and 160oC for 60 minutes. Upon cooling, the residue





4

Single crystal of 1 was mounted on a glass fiber and transferred to a Bruker Kappa APEX

II CCD diffractometer. The APEX2 software program was used to determine the unite cell

parameters and data collection. The data were collected at 100K using Oxford Cryostream Plus

system. The raw frame data were processed using APEX2 program. The absorption correction

was applied using program SADABS. Subsequent calculations were carried out using SHELXTL

program. All non-H atoms were refined anisotropically. Carbon-bound hydrogen atoms were

placed in calculated positions using an appropriate riding model and coupled isotropic

temperature factors.

Synthesis and Characterization of DTS(PTTh2)2:

Synthesis of 5,5’-bis{(4-(7-bromo-[1,2,5]thiadiazolo[3,4-c]pyridine)}-3,3’-di-2-

ethylhexylsilylene-2,2’-bithiophene (1): In a N2 filled glove box a 20 mL microwave tube was

charged with 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine (PTBr2, 790 mg, 2.68 mmol), 5,5’-

Bis(trimethylstannyl)-3,3’-di-2-ethylhexylsilylene-2,2’-bithiophene (DTS(SnMe3)2, 800 mg, 1.07

mmol), Pd(PPh3)4 (0.025 g, 0.02 mmol), toluene (15 mL), and sealed with a Teflon® cap. Using

a Biotage microwave reactor with stirring (900 rpm), the reaction mixture was heated to 80oC for

5 minutes, 100oC for 5 minutes, 120oC for 5 minutes, 140oC for 5 minutes, and 160oC for 60

minutes. Upon cooling, the purple residue was passed through a short silica plug eluting with

CHCl3 (1% Et3N) (~500 mL). All volatiles were removed in vacuo to give the crude product as a

dark sticky solid. The material was then slurried in methanol (300 mL), filtered, loaded onto

silica using CHCl3 and purified by flash chromatography using a hexanes/CHCl3 gradient. The

silica gel was pre-treated with hexanes/Et3N (90:10). The product eluted as a purple solution at

~50% CHCl3. After fraction collection and solvent removal, the solid product was slurried in

5

methanol (300 mL), sonicated for 30 minutes, and filtered. The solid was washed with copious

amounts of methanol and acetone, and then dried under vacuum for 24 hours. The product was

collected as green metallic coloured powder. Recovered yield: 650 mg (72%). 1H NMR

(CDCl3): δ 8.76 (s, 2H, DTS-CH), 8.65 (s, 2H, PT-CH), 1.52 (m, 2H, CH),1.39 (m, 4H, CH2),

1.31 (m, 4H, CH2), 1.16 (m, 8H, CH2), 1.06 (m, 4H, CH2), 0.85 (m, 12H, CH3). 13C{1H} NMR

(CDCl3): 156.38, 153.85, 147.98, 147.66, 147.49 (s, quaternary), 146.03 (s, CH), 143.94 (s,

quaternary), 135.99 (s, CH), 107.64 (s, quaternary), 36.02 (s, CH), 35.76 (s, CH2), 22.97 (s,

CH2), 22.93 (s, CH2), 20.92 (s, CH2), 17.64 (s, CH2), 14.15 (s, CH3). 10.80 (s, CH3). Elemental

analysis calculated for C34H38Br2N6S4Si: C, 48.22; H, 4.52; N, 9.92. Found: C, 48.3; H, 4.56; N,

9.82 %. UV-Visible Absorbance: (CHCl3) λmax = 575 nm, λonset = 625 nm. (As Cast Film) λmax =

585, 625 nm, λonset = 682 nm. Single Crystal X-Ray Diffraction: Crystals grown from slow

evaporation of CHCl3. Triclinic, P-1. Cell: a = 11.7963(7) Å, b = 13.0288(8) Å, c = 13.8853(8)

Å, alpha = 98.624(2)° beta = 103.354(2)° gamma = 97.552(2)°. V = 2022.1(2) Å3. R1 = 0.0653,

wR2 = 0.1678.

Synthesis of 5,5’-bis{(4-(7-hexylthiophen-2-yl)thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-

c]pyridine}-3,3’-di-2-ethylhexylsilylene-2,2’-bithiophene (DTS(PTTh2)2): In a N2 filled glove

box, a 20 mL microwave tube was charged with 5,5’-bis{(4-(7-bromo-[1,2,5]thiadiazolo[3,4-

c]pyridine)}-3,3’-di-2-ethylhexylsilylene-2,2’-bithiophene (1, 420 mg, 0.50 mmol), 5'-hexyl-

2,2'-bithiophene-5-trimethylstannane (450 mg, 1.09 mmol), Pd(PPh3)4 (0.025 g, 0.02 mmol),

toluene (15 mL), and sealed with a Teflon® cap. Using a Biotage microwave reactor with

stirring (900 rpm), the reaction mixture was heated to 80oC for 5 minutes, 100oC for 5 minutes,

120oC for 5 minutes, 140oC for 5 minutes, and 160oC for 60 minutes. Upon cooling, the residue





6

was passed through a short silica plug eluting with CHCl3 (1% Et3N, 500 mL). All volatiles were

removed in vacuo to give the crude product as a purple solid. The material was slurried in

methanol (300 mL), filtered, then loaded onto silica using CHCl3 and purified by flash

chromatography using a hexanes/CHCl3 (1% Et3N) gradient. The silica gel was pre-treated with

hexanes/Et3N (90:10). The product eluted as a blue solution at ~20% CHCl3 (1% Et3N). A purple

solid was obtained after fraction collection and solvent removal. Purification by silica column

chromatography was carried out several times to ensure purity for device fabrication. The final

solid was slurried in methanol (300 mL), sonicated for 30 minutes, and filtered. The solid was

washed with copious amounts of hexanes:methanol (25:75), methanol and finally acetone. The

solid was dried under vacuum for 24 hours. The product was collected as a purple solid.

Recovered yield: 475 mg (81%). 1H NMR (CDCl3): δ 8.72 (t, 2H, DTS-CH), 8.70 (s, 2H, PT-

CH), 7.95 (d, 3JH-H = 5 Hz, 2H, Th-CH), 7.16 (d, 3JH-H = 5 Hz, 2H, Th-CH), 7.11 (d, 3JH-H = 5

Hz, 2H, Th-CH), 6.73 (d, 3JH-H = 5 Hz, 2H, Th-CH), 2.83 (t, 3JH-H = 8 Hz, 4H Th-CH2), 1.72 (h,

3JH-H = 6 Hz, 4H, CH2), 1.62 (m, 2H, CH), 1.41 (m, 8H, CH2), 1.35 (m, 12H, CH2), 1.28 (m, 8H,

CH2), 1.18 (m, 4H, SiCH2), 0.92-0.83 (m, 18H, CH3). 13C{1H} NMR (CDCl3): 154.56, 153.65,

147.98, 147.43, 146.27, 145.76, 144.77, 140.43 (s, quaternary), 139.63 (s, PT-CH), 135.19,

134.85 (s, quaternary), 134.44 (s, DTS-CH), 128.42 (s, Th-CH), 125.01 (s, Th-CH), 123.99 (s,

Th-CH), 123.85 (s, Th-CH), 119.59 (s, quaternary), 36.10 (s, CH), 35.86 (s, CH2), 31.57 (s, Si-

CH2), 30.26 (s, Th-CH2), 29.08 (s, CH2), 29.01 (s, CH2), 28.80 (s, CH2), 23.08 (s, CH2), 22.59 (s,

CH2), 17.73 (s, CH2), 14.26 (s, CH3), 14.09 (s, CH3), 10.88 (s, CH3). Elemental analysis

calculated for C62H72N6S8Si: C, 62.79; H, 6.12; N, 7.09; found: C, 62.9; H, 6.24; N, 7.18 %.

LRMS (FD) m/z, calcd for C62H72N6S8Si (M+): 1184; found: 1184. UV-Visible Absorbance:

(CHCl3) λmax = 655 nm, λonset = 715 nm. (As Cast Film) λmax = 655, 725 nm, λonset = 815 nm.

7

Scheme S1. Synthetic route towards DTS(PTTh2)2

Description of DTS(PTTh2)2: The core A/D/A structure 5,5’-bis{(4-(7-bromo-

[1,2,5]thiadiazolo[3,4-c]pyridine)}-3,3’-di-2-ethylhexylsilylene-2,2’-bithiophene (1), was

synthesized via a microwave-assisted Stille cross coupling procedure between 5,5’-

bis(trimethylstannyl)-3,3’-di-2-ethylhexylsilylene-2,2’-bithiophene (DTS(SnMe3)2) and 2.5

equivalents of 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine (PTBr2), as shown in Scheme S1.

Preferential oxidative coupling occurs at the more electron deficient 4-carbon position of PTBr2





6

was passed through a short silica plug eluting with CHCl3 (1% Et3N, 500 mL). All volatiles were

removed in vacuo to give the crude product as a purple solid. The material was slurried in

methanol (300 mL), filtered, then loaded onto silica using CHCl3 and purified by flash

chromatography using a hexanes/CHCl3 (1% Et3N) gradient. The silica gel was pre-treated with

hexanes/Et3N (90:10). The product eluted as a blue solution at ~20% CHCl3 (1% Et3N). A purple

solid was obtained after fraction collection and solvent removal. Purification by silica column

chromatography was carried out several times to ensure purity for device fabrication. The final

solid was slurried in methanol (300 mL), sonicated for 30 minutes, and filtered. The solid was

washed with copious amounts of hexanes:methanol (25:75), methanol and finally acetone. The

solid was dried under vacuum for 24 hours. The product was collected as a purple solid.

Recovered yield: 475 mg (81%). 1H NMR (CDCl3): δ 8.72 (t, 2H, DTS-CH), 8.70 (s, 2H, PT-

CH), 7.95 (d, 3JH-H = 5 Hz, 2H, Th-CH), 7.16 (d, 3JH-H = 5 Hz, 2H, Th-CH), 7.11 (d, 3JH-H = 5

Hz, 2H, Th-CH), 6.73 (d, 3JH-H = 5 Hz, 2H, Th-CH), 2.83 (t, 3JH-H = 8 Hz, 4H Th-CH2), 1.72 (h,

3JH-H = 6 Hz, 4H, CH2), 1.62 (m, 2H, CH), 1.41 (m, 8H, CH2), 1.35 (m, 12H, CH2), 1.28 (m, 8H,

CH2), 1.18 (m, 4H, SiCH2), 0.92-0.83 (m, 18H, CH3). 13C{1H} NMR (CDCl3): 154.56, 153.65,

147.98, 147.43, 146.27, 145.76, 144.77, 140.43 (s, quaternary), 139.63 (s, PT-CH), 135.19,

134.85 (s, quaternary), 134.44 (s, DTS-CH), 128.42 (s, Th-CH), 125.01 (s, Th-CH), 123.99 (s,

Th-CH), 123.85 (s, Th-CH), 119.59 (s, quaternary), 36.10 (s, CH), 35.86 (s, CH2), 31.57 (s, Si-

CH2), 30.26 (s, Th-CH2), 29.08 (s, CH2), 29.01 (s, CH2), 28.80 (s, CH2), 23.08 (s, CH2), 22.59 (s,

CH2), 17.73 (s, CH2), 14.26 (s, CH3), 14.09 (s, CH3), 10.88 (s, CH3). Elemental analysis

calculated for C62H72N6S8Si: C, 62.79; H, 6.12; N, 7.09; found: C, 62.9; H, 6.24; N, 7.18 %.

LRMS (FD) m/z, calcd for C62H72N6S8Si (M+): 1184; found: 1184. UV-Visible Absorbance:

(CHCl3) λmax = 655 nm, λonset = 715 nm. (As Cast Film) λmax = 655, 725 nm, λonset = 815 nm.

7

Scheme S1. Synthetic route towards DTS(PTTh2)2

Description of DTS(PTTh2)2: The core A/D/A structure 5,5’-bis{(4-(7-bromo-

[1,2,5]thiadiazolo[3,4-c]pyridine)}-3,3’-di-2-ethylhexylsilylene-2,2’-bithiophene (1), was

synthesized via a microwave-assisted Stille cross coupling procedure between 5,5’-

bis(trimethylstannyl)-3,3’-di-2-ethylhexylsilylene-2,2’-bithiophene (DTS(SnMe3)2) and 2.5

equivalents of 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine (PTBr2), as shown in Scheme S1.

Preferential oxidative coupling occurs at the more electron deficient 4-carbon position of PTBr2





8

leading to the pyridal N-atoms proximal to the DTS donor.2 The connectivity of 1 was confirmed

by analysis of single crystals via X-ray diffraction (Figure S6). With reactive Br atoms at the

terminal ends of the molecule, compound 1 presents itself as a universal platform for which to

build light harvesting small molecules, via the attachment of conjugated terminal end groups.

The target compound DTS(PTTh2)2 was synthesized by coupling 1 and two equivalents of 5'-

hexyl-2,2'-bithiophene-5-trimethylstannane and obtained in yields >80%. It is important to

highlight the regio-chemistry of DTS(PTTh2)2, where the pyridal N-atoms of each PT acceptor

unit are orientated towards the central DTS donor moiety (proximal configuration). This

conformation was confirmed by a NMR spectroscopy 1H-1H NOE experiment where a cross

correlation peak between the PT CH and thiophene CH resonance was observed (see Figure S3),

and is distinctly different from a related small molecule we recently reported, where the pyridal

N-atoms point away from the DTS core (distal configuration).3 Differential scanning calorimetry

reveals that DTS(PTTh2)2 melts at ~ 210 °C and crystallizes at ~ 168 °C.

Important practical note on purity: during the synthesis of DTS(PTTh2)2, the selectivity

for 2-hexylbithiophene transfer during the transmetalation step of the of microwave assisted

Stille-coupling procedure is reduced at elevated temperatures (>160 °C). At these higher

temperatures one observed the formation of an organic side product (~1-2%) in which one end

of the A/D/A molecule is methyl terminated instead of 2-hexylbithiophene terminated. This

impurity (identified via mass spectrometry) must be rigorously avoided as it causes degradation

of the device performance. Contamination can be avoided by carefully monitoring reaction

conditions or removed from the desired DTS(PTTh2)2 product via extraction with hexanes.

9

NMR Spectra:

Figure S1: 1H NMR spectrum of compound DTS(PTTh2)2 at 300K in CDCl3 (δ 7.27 ppm).





8

leading to the pyridal N-atoms proximal to the DTS donor.2 The connectivity of 1 was confirmed

by analysis of single crystals via X-ray diffraction (Figure S6). With reactive Br atoms at the

terminal ends of the molecule, compound 1 presents itself as a universal platform for which to

build light harvesting small molecules, via the attachment of conjugated terminal end groups.

The target compound DTS(PTTh2)2 was synthesized by coupling 1 and two equivalents of 5'-

hexyl-2,2'-bithiophene-5-trimethylstannane and obtained in yields >80%. It is important to

highlight the regio-chemistry of DTS(PTTh2)2, where the pyridal N-atoms of each PT acceptor

unit are orientated towards the central DTS donor moiety (proximal configuration). This

conformation was confirmed by a NMR spectroscopy 1H-1H NOE experiment where a cross

correlation peak between the PT CH and thiophene CH resonance was observed (see Figure S3),

and is distinctly different from a related small molecule we recently reported, where the pyridal

N-atoms point away from the DTS core (distal configuration).3 Differential scanning calorimetry

reveals that DTS(PTTh2)2 melts at ~ 210 °C and crystallizes at ~ 168 °C.

Important practical note on purity: during the synthesis of DTS(PTTh2)2, the selectivity

for 2-hexylbithiophene transfer during the transmetalation step of the of microwave assisted

Stille-coupling procedure is reduced at elevated temperatures (>160 °C). At these higher

temperatures one observed the formation of an organic side product (~1-2%) in which one end

of the A/D/A molecule is methyl terminated instead of 2-hexylbithiophene terminated. This

impurity (identified via mass spectrometry) must be rigorously avoided as it causes degradation

of the device performance. Contamination can be avoided by carefully monitoring reaction

conditions or removed from the desired DTS(PTTh2)2 product via extraction with hexanes.

9

NMR Spectra:

Figure S1: 1H NMR spectrum of compound DTS(PTTh2)2 at 300K in CDCl3 (δ 7.27 ppm).





10

Figure S2. 13C NMR spectrum of compound DTS(PTTh2)2 at 300K in CDCl3 (δ 77 ppm).

11

Figure S3: 1H-1H NOE NMR spectrum of compound DTS(PTTh2)2 at 300K in CDCl3 (δ 7.27

ppm). Cross peak between CH proton 1 and CH proton 2 confirms proposed regio-chemistry of

molecule.





10

Figure S2. 13C NMR spectrum of compound DTS(PTTh2)2 at 300K in CDCl3 (δ 77 ppm).

11

Figure S3: 1H-1H NOE NMR spectrum of compound DTS(PTTh2)2 at 300K in CDCl3 (δ 7.27

ppm). Cross peak between CH proton 1 and CH proton 2 confirms proposed regio-chemistry of

molecule.





12

Figure S4. 1H NMR spectrum of compound 1 at 300K in CDCl3 (δ 7.27 ppm).

13

Figure S5. Normalized UV-visible absorption spectra of compound 1in CHCl3 solution (black), and as a thin film cast from CHCl3 on quartz substrate (red).





12

Figure S4. 1H NMR spectrum of compound 1 at 300K in CDCl3 (δ 7.27 ppm).

13

Figure S5. Normalized UV-visible absorption spectra of compound 1in CHCl3 solution (black), and as a thin film cast from CHCl3 on quartz substrate (red).





14

Single Crystal X-Ray Diffraction

Figure S6. Single crystal X-ray structure of 1. a) front view and b) side view. (Carbon) black;

Nitrogen) blue; Silicon) red; Sulfur) yellow; Bromine) brown. Hydrogen atoms and 2-ethylhexyl

side chains omitted for clarity. Thermal ellipsoid probability = 50%. Triclinic, P-1. Cell: a =

11.7963(7) Å, b = 13.0288(8) Å, c = 13.8853(8) Å, alpha = 98.624(2)° beta = 103.354(2)°

gamma = 97.552(2)°. V = 2022.1(2) Å3. R1 = 0.0653, wR2 = 0.1678. This solid state structure

confirms the proposed regio-chemistry and spatial orientation of the DTS donor and PT acceptor

units.

15

Physical Characterization:

Figure S7. Differential scanning calorimetry plot of DTS(PTTh2)2. Scan rate = 10 °C/min from 0

°C to 300 °C.

Figure S8. Cyclic voltammetry plots of DTS(PTTh2)2 obtained in CH2Cl2 solution. A) Raw data

using Ag/Ag+ reference. b) Internally referenced to Fc/Fc+ (set to 0V) with oxidation onset =

0.321V and reduction onset = -1.31V.





14

Single Crystal X-Ray Diffraction

Figure S6. Single crystal X-ray structure of 1. a) front view and b) side view. (Carbon) black;

Nitrogen) blue; Silicon) red; Sulfur) yellow; Bromine) brown. Hydrogen atoms and 2-ethylhexyl

side chains omitted for clarity. Thermal ellipsoid probability = 50%. Triclinic, P-1. Cell: a =

11.7963(7) Å, b = 13.0288(8) Å, c = 13.8853(8) Å, alpha = 98.624(2)° beta = 103.354(2)°

gamma = 97.552(2)°. V = 2022.1(2) Å3. R1 = 0.0653, wR2 = 0.1678. This solid state structure

confirms the proposed regio-chemistry and spatial orientation of the DTS donor and PT acceptor

units.

15

Physical Characterization:

Figure S7. Differential scanning calorimetry plot of DTS(PTTh2)2. Scan rate = 10 °C/min from 0

°C to 300 °C.

Figure S8. Cyclic voltammetry plots of DTS(PTTh2)2 obtained in CH2Cl2 solution. A) Raw data

using Ag/Ag+ reference. b) Internally referenced to Fc/Fc+ (set to 0V) with oxidation onset =

0.321V and reduction onset = -1.31V.





16

Figure S9. UV-visible absorption spectra of DTS(PTTh2)2 in ortho-dichlorobenzene solution at

25 °C (solid), 100 °C (dashed) and cooled from 100 °C to 25 °C (dotted). The large shoulder at

the longer wavelengths disappears upon heating to 100 °C, a indication that DTS(PTTh2)2

aggregates in solution at ambient temperatures.

17

OFET Characterization:

Figure S10. Performance of the OFET based on pristine DTS(PTTh2)2. a) Output curve and b)

transfer curve (Vds=-60 V).

Figure S11. Transfer characteristics of bipolar field-effect transistors based on

DTS(PTTh2)2/PC70BM blended films processed with and without DIO additives.

-60 -50 -40 -30 -20 -10 0 1010-1110-1010-910-810-710-610-510-4

⎪Ids⎪1/

2 (mA

1/2 )

⎪Ids⎪

Vgs (V)

14.0

0.02.04.06.0

8.010.0

12.0

0 -10 -20 -30 -40 -50 -60

I ds (µ

A)

Vds (V)

-20 V-30 V

-40 V

-50 V

-60 V

0.0

-20.0

-40.0

-60.0

-80.0

-100.0 a b

-60 -40 -20 0 20 40 6010-10

10-9

10-8

10-7

10-6

10-5

10-10

10-9

10-8

10-7

10-6

10-5

n-type mode

with 0.25% DIO w/o DIO

I ds (V

)

Vgs (V)

p-type mode





16

Figure S9. UV-visible absorption spectra of DTS(PTTh2)2 in ortho-dichlorobenzene solution at

25 °C (solid), 100 °C (dashed) and cooled from 100 °C to 25 °C (dotted). The large shoulder at

the longer wavelengths disappears upon heating to 100 °C, a indication that DTS(PTTh2)2

aggregates in solution at ambient temperatures.

17

OFET Characterization:

Figure S10. Performance of the OFET based on pristine DTS(PTTh2)2. a) Output curve and b)

transfer curve (Vds=-60 V).

Figure S11. Transfer characteristics of bipolar field-effect transistors based on

DTS(PTTh2)2/PC70BM blended films processed with and without DIO additives.

-60 -50 -40 -30 -20 -10 0 1010-1110-1010-910-810-710-610-510-4

⎪Ids⎪1/

2 (mA

1/2 )

⎪Ids⎪

Vgs (V)

14.0

0.02.04.06.0

8.010.0

12.0

0 -10 -20 -30 -40 -50 -60

I ds (µ

A)

Vds (V)

-20 V-30 V

-40 V

-50 V

-60 V

0.0

-20.0

-40.0

-60.0

-80.0

-100.0 a b

-60 -40 -20 0 20 40 6010-10

10-9

10-8

10-7

10-6

10-5

10-10

10-9

10-8

10-7

10-6

10-5

n-type mode

with 0.25% DIO w/o DIO

I ds (V

)

Vgs (V)

p-type mode





18

Solar Cell Characterization:

Figure S12. IPCE spectra of SM-BHJ solar cells based on DTS(PTTh2)2/PC70BM active layer

with different blend ratios.

300 400 500 600 700 800 9000

10

20

30

40

50

60

IPC

E (%

)

wavelength (nm)

80:20 70:30 60:40 50:50

1 2 3 4 5 640

45

50

55

60

FF (%

)

Process run1 2 3 4 5 6

4.0

4.5

5.0

5.5

6.0

6.5

7.0

PCE

(%)

Process run

1 2 3 4 5 610

11

12

13

14

15

J sc (m

A/c

m2 )


0.70

0.72

0.74

0.76

0.78

0.80

V oc (V

)

Process run

19

Figure S13. The performance distribution of SM-BHJ solar cells based on

DTS(PTTh2)2/PC70BM active layers with 0.25% DIO (v/v). Six independent process runs were

made and each for each process run at least 2 cells were tested (total 14 cells). The average PCE

is ≈6.2%.

Figure S14. Current-voltage (J-V) characteristics and IPCE spectrum of SM-BHJ solar cells

based on DTS(PTTh2)2/PC70BM (70:30) active layer with thickness of ~100 nm (Films cast from

4% w/v CB with 0.25% DIO v/v solvent additive).

0.0 0.2 0.4 0.6 0.8 1.0

-10

-5

0

5

10

15Voc=0.784 VIsc=11.73 mA/cm2

FF=61.2%PCE=5.63%

Cur

rent

den

sity

(mA

/cm

2 )

Voltage (V)300 400 500 600 700 800 9000

10

20

30

40

50

60

IPC

E (%

)

Wavelength (nm)

a b





18

Solar Cell Characterization:

Figure S12. IPCE spectra of SM-BHJ solar cells based on DTS(PTTh2)2/PC70BM active layer

with different blend ratios.

300 400 500 600 700 800 9000

10

20

30

40

50

60

IPC

E (%

)

wavelength (nm)

80:20 70:30 60:40 50:50

1 2 3 4 5 640

45

50

55

60

FF (%

)


4.0

4.5

5.0

5.5

6.0

6.5

7.0

PCE

(%)

Process run

1 2 3 4 5 610

11

12

13

14

15

J sc (m

A/c

m2 )


0.70

0.72

0.74

0.76

0.78

0.80

V oc (V

)

Process run

19

Figure S13. The performance distribution of SM-BHJ solar cells based on

DTS(PTTh2)2/PC70BM active layers with 0.25% DIO (v/v). Six independent process runs were

made and each for each process run at least 2 cells were tested (total 14 cells). The average PCE

is ≈6.2%.

Figure S14. Current-voltage (J-V) characteristics and IPCE spectrum of SM-BHJ solar cells

based on DTS(PTTh2)2/PC70BM (70:30) active layer with thickness of ~100 nm (Films cast from

4% w/v CB with 0.25% DIO v/v solvent additive).

0.0 0.2 0.4 0.6 0.8 1.0

-10

-5

0

5

10

15Voc=0.784 VIsc=11.73 mA/cm2

FF=61.2%PCE=5.63%

Cur

rent

den

sity

(mA

/cm

2 )

Voltage (V)300 400 500 600 700 800 9000

10

20

30

40

50

60

IPC

E (%

)

Wavelength (nm)

a b





20

TEM Image Processing for DTS(PTTh2)2/PC70BM Films:

Here we present the algorithm used to determine crystalline/amorphous regions, extract

the direction, and construct the false-colored image in Fig. 3 from the raw TEM images. As

shown in Figure 3, lattice planes are resolvable in the raw data; however, presentation is

complicated by showing the small-scale fringes and large-scale changes in the morphology

change. After deciding which areas are crystalline (amorphous), we validate the analysis by

masking the crystalline (amorphous) areas of the raw image, computing the azimuthally

integrated power spectrum, and comparing with power spectrum of the original image. The

discrimination of amorphous/crystalline regions was inspired by the work of Fan, et. al., and the

use of false-colors by Zhang, et. al.4,5

The raw images were taken at a defocus close to -1 um for the pristine BHJ and 0.25%

v/v DIO BHJ samples. Azimuthally integrated power spectra for the raw images (normalized

relative to the mean intensity value) are shown in Fig. S15 accompanied by the power spectrum

of the theoretical 1-D microscope contrast transfer function (CTF) at a -1000 nm defocus.5 We

see the sharp peak associated with the crystal lattice fringes around 0.31 Å-1 for all samples that

coincides with the maximum of the first CTF peak; thus, the images of the lattice planes should

not be distorted by the CTF.6 The peak sits on a broader distribution indicative of amorphous

material along with a shot noise background that is not modulated by the CTF.

21

Figure S15: Azimuthally integrated power spectrum from BHJ raw images: blue is from film

cast from pure solvent, red is from film cast from 0.25% DIO solvent additive (optimal) device.

The black, dashed line represents the theoretical |CTF|2 for a defocus of -1000 nm.

To determine the crystalline/amorphous regions of the image, a raw image, 2048 px ×

2048 px (656 nm per side), was broken into a series of small 16 px ×16 px images (5.12 nm per

side). The manipulation of the small image is shown pictorially in Fig. S16. The mean value of

the small image was subtracted and the image was padded by zeros (32 px × 32 px total) to avoid

wrap around effects. The 2-D power spectrum (symmetric about q=0 as the data is real) was

computed and multiplied by a binary, isotropic mask centered on q = 0.31 Å-1 with a bandwidth

of 0.10 Å-1 for each small image. In regions of the raw image where we observe bright fringes,

the 2-D spectra show bright spots corresponding to the direction. This was turned into a coarse,

spatially resolved map by tessellating the 2-D spectra as shown in Fig. S17. For this figure, the

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1x 10-9

q (Å-1)

Powe

r Spe

ctru

m (A

rb.)





20

TEM Image Processing for DTS(PTTh2)2/PC70BM Films:

Here we present the algorithm used to determine crystalline/amorphous regions, extract

the direction, and construct the false-colored image in Fig. 3 from the raw TEM images. As

shown in Figure 3, lattice planes are resolvable in the raw data; however, presentation is

complicated by showing the small-scale fringes and large-scale changes in the morphology

change. After deciding which areas are crystalline (amorphous), we validate the analysis by

masking the crystalline (amorphous) areas of the raw image, computing the azimuthally

integrated power spectrum, and comparing with power spectrum of the original image. The

discrimination of amorphous/crystalline regions was inspired by the work of Fan, et. al., and the

use of false-colors by Zhang, et. al.4,5

The raw images were taken at a defocus close to -1 um for the pristine BHJ and 0.25%

v/v DIO BHJ samples. Azimuthally integrated power spectra for the raw images (normalized

relative to the mean intensity value) are shown in Fig. S15 accompanied by the power spectrum

of the theoretical 1-D microscope contrast transfer function (CTF) at a -1000 nm defocus.5 We

see the sharp peak associated with the crystal lattice fringes around 0.31 Å-1 for all samples that

coincides with the maximum of the first CTF peak; thus, the images of the lattice planes should

not be distorted by the CTF.6 The peak sits on a broader distribution indicative of amorphous

material along with a shot noise background that is not modulated by the CTF.

21

Figure S15: Azimuthally integrated power spectrum from BHJ raw images: blue is from film

cast from pure solvent, red is from film cast from 0.25% DIO solvent additive (optimal) device.

The black, dashed line represents the theoretical |CTF|2 for a defocus of -1000 nm.

To determine the crystalline/amorphous regions of the image, a raw image, 2048 px ×

2048 px (656 nm per side), was broken into a series of small 16 px ×16 px images (5.12 nm per

side). The manipulation of the small image is shown pictorially in Fig. S16. The mean value of

the small image was subtracted and the image was padded by zeros (32 px × 32 px total) to avoid

wrap around effects. The 2-D power spectrum (symmetric about q=0 as the data is real) was

computed and multiplied by a binary, isotropic mask centered on q = 0.31 Å-1 with a bandwidth

of 0.10 Å-1 for each small image. In regions of the raw image where we observe bright fringes,

the 2-D spectra show bright spots corresponding to the direction. This was turned into a coarse,

spatially resolved map by tessellating the 2-D spectra as shown in Fig. S17. For this figure, the

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1x 10-9

q (Å-1)

Powe

r Spe

ctru

m (A

rb.)





22

spatial resolution of the map was doubled in each dimension by overlapping the small images

(i.e. oversampling by the raw data). In regions of what we interpret as overlapping crystals,

multiple sets of spots in different directions were observed; amorphous regions produced a faint

halo.

Figure S16. Graphical depiction of the small image processing: a) A typically small image

(crystalline area), b) The padded image, c) 2-D power spectrum (q=0 at the center), d) 2-D power

spectrum masked about 0.31 Å-1 with a bandwidth of 0.15 Å-1.

Figure S17: A side-by-side comparison of the a) raw data and b) the tessellated, masked 2-D

power spectra. We note that tessellated data is oversampled by a factor of two in each dimension

a

a b

b c d

23

(i.e. the power spectra are not independent of their neighbors) to improve fill space and improve

the spatial resolution.

To extract the direction of a 2-D power spectrum, the spectrum was multiplied by a set of

six partially overlapping, directional masks (Fig. S18a). The direction maximizing the integrated

power was recorded as the dominant orientation (Fig. S18b). To first order, this approach does a

remarkable job of finding the orientation of the crystallites; however, it could be improved by

tracking multiple directions in regions with overlapping crystals. We also recorded the integrated

power of the dominant, directionally masked 2-D spectrum (Fig. S18c). A binary mask

determining crystalline/amorphous regions was created by setting a power threshold on this

spatial map of the integrated power the 2-D spectrum. This is then smoothed using a Gaussian

kernel (radius of 1.6 nm) and another threshold of 0.9 was applied to reduce noise. We self-

consistently validate the choice of power threshold by applying the mask and inverted mask to

the raw image (the mean value was removed from the raw image first) and calculating the

azimuthally integrated power spectra as shown in Fig. S19. For both the BHJ films cast from

pure solvent and with 0.25% DIO solvent additive, the algorithm shows good selectivity; the

spectral power of the peak is mostly within the regions covered by the crystalline mask.

Adjusting the threshold on the 0.25% v/v DIO solvent additive image did not change the results

appreciably and, for simplicity, the thresholds were kept the same for both images.





22

spatial resolution of the map was doubled in each dimension by overlapping the small images

(i.e. oversampling by the raw data). In regions of what we interpret as overlapping crystals,

multiple sets of spots in different directions were observed; amorphous regions produced a faint

halo.

Figure S16. Graphical depiction of the small image processing: a) A typically small image

(crystalline area), b) The padded image, c) 2-D power spectrum (q=0 at the center), d) 2-D power

spectrum masked about 0.31 Å-1 with a bandwidth of 0.15 Å-1.

Figure S17: A side-by-side comparison of the a) raw data and b) the tessellated, masked 2-D

power spectra. We note that tessellated data is oversampled by a factor of two in each dimension

a

a b

b c d

23

(i.e. the power spectra are not independent of their neighbors) to improve fill space and improve

the spatial resolution.

To extract the direction of a 2-D power spectrum, the spectrum was multiplied by a set of

six partially overlapping, directional masks (Fig. S18a). The direction maximizing the integrated

power was recorded as the dominant orientation (Fig. S18b). To first order, this approach does a

remarkable job of finding the orientation of the crystallites; however, it could be improved by

tracking multiple directions in regions with overlapping crystals. We also recorded the integrated

power of the dominant, directionally masked 2-D spectrum (Fig. S18c). A binary mask

determining crystalline/amorphous regions was created by setting a power threshold on this

spatial map of the integrated power the 2-D spectrum. This is then smoothed using a Gaussian

kernel (radius of 1.6 nm) and another threshold of 0.9 was applied to reduce noise. We self-

consistently validate the choice of power threshold by applying the mask and inverted mask to

the raw image (the mean value was removed from the raw image first) and calculating the

azimuthally integrated power spectra as shown in Fig. S19. For both the BHJ films cast from

pure solvent and with 0.25% DIO solvent additive, the algorithm shows good selectivity; the

spectral power of the peak is mostly within the regions covered by the crystalline mask.

Adjusting the threshold on the 0.25% v/v DIO solvent additive image did not change the results

appreciably and, for simplicity, the thresholds were kept the same for both images.





24

Figure S18. Recording direction and intensity: a) masks used to determine the dominant

direction present in the 2-D power spectra, b) spatial map of dominant orientation, and c) spatial

map of the integrated power of the dominant, directionally masked 2-D spectrum. For this

analysis, the small images are still 16 px ×16 px but the spatial maps are 8× oversampled (i.e.

quasi-2 px resolution).

a

b c

25

Figure S19. Validation for the choice of power threshold. Azimuthally integrated spectrum of

the raw image is in blue, the crystalline areas of the raw image (raw image × crystalline mask) is

in green, and the amorphous areas of the raw image (raw image × inverted crystalline mask) is in

red: a) BHJ film cast from pure solvent and b) BHJ film cast with 0.25% DIO solvent additive.

The threshold for a) and b) was the same. The increase of low q spectral power in a) is due to an

area of the raw image where the grid support is visible and the mean value is locally, not zero;

thus, multiplication by the mask created extra spectral power at low q.

Important practical note on controlling phase separation: Since DTS(PTTh2)2 has a strong

tendency to crystalline, the nanomorphology of BHJ active layer is found to be sensitive to at

least the following parameters: the absolute purity of DTS(PTTh2)2, the temperature of the active

solutions at which the films are cast, and the precision of the added amount of optimal DIO

concentration. Only domains of DTS(PTTh2)2 with 15-20 nm dimensions were found to lead to

high PCEs. Domains larger than 20 nm dimensions show decreased device performance (<6%).

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80

1

2

3

4

5

6

7

8

9x 10-10

q (Å-1)

Powe

r Spe

ctru

m (A

rb.)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80

1

2

3

4

5

6x 10-10

q (Å-1)

Powe

r Spe

ctru

m (A

rb.)

a b





24

Figure S18. Recording direction and intensity: a) masks used to determine the dominant

direction present in the 2-D power spectra, b) spatial map of dominant orientation, and c) spatial

map of the integrated power of the dominant, directionally masked 2-D spectrum. For this

analysis, the small images are still 16 px ×16 px but the spatial maps are 8× oversampled (i.e.

quasi-2 px resolution).

a

b c

25

Figure S19. Validation for the choice of power threshold. Azimuthally integrated spectrum of

the raw image is in blue, the crystalline areas of the raw image (raw image × crystalline mask) is

in green, and the amorphous areas of the raw image (raw image × inverted crystalline mask) is in

red: a) BHJ film cast from pure solvent and b) BHJ film cast with 0.25% DIO solvent additive.

The threshold for a) and b) was the same. The increase of low q spectral power in a) is due to an

area of the raw image where the grid support is visible and the mean value is locally, not zero;

thus, multiplication by the mask created extra spectral power at low q.

Important practical note on controlling phase separation: Since DTS(PTTh2)2 has a strong

tendency to crystalline, the nanomorphology of BHJ active layer is found to be sensitive to at

least the following parameters: the absolute purity of DTS(PTTh2)2, the temperature of the active

solutions at which the films are cast, and the precision of the added amount of optimal DIO

concentration. Only domains of DTS(PTTh2)2 with 15-20 nm dimensions were found to lead to

high PCEs. Domains larger than 20 nm dimensions show decreased device performance (<6%).

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80

1

2

3

4

5

6

7

8

9x 10-10

q (Å-1)

Powe

r Spe

ctru

m (A

rb.)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80

1

2

3

4

5

6x 10-10

q (Å-1)

Powe

r Spe

ctru

m (A

rb.)

a b





26

References:

1. Bard, Allen J.; Larry R. Faulkner (2000-12-18). Electrochemical Methods: Fundamentals

and Applications (2 ed.). Wiley.

2. Handy, S. T.; Wilson, T. and Muth, A. Disubstituted Pyridines: The Double-Coupling

Approach. J. Org. Chem. 72, 8496-8500 (2007).

3. Welch, G. C. et al. A modular molecular framework for utility in small-molecule

solution-processed organic photovoltaic devices. J. Mater. Chem. 21, 12700–12709

(2011).

4. Fan, G. Y. & Cowley, J. M. Auto-correlation analysis of high resolution electron

micrographs of near-amorphous thin films. Ultramicroscopy 17, 345-456 (1985).

5. Zhang, X. et al. In-Plane Liquid Crystalline Texture of High-Performance

Thienothiophene Copolymer Thin Films. Adv. Funct. Mater. 20, 4098-4106 (2010).

6. Reimer, L. et al. Transmission electron microscopy:physics of image formation and

microanalysis, xiii, 545 p. (Springer-Verlag, Berlin ; New York, 1993).





Documents

DOI: 10.1038/NMAT3160 Supporting Information · molecular sieves (4 Å). Chloroform was dried over calcium hydride, distilled under vacuum, and stored over molecular sieves (4 Å)