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Supporting information for

Chemical reaction between ITIC electron acceptor and amine-

containing interfacial layer in non-fullerene solar cells

Lin Hu, Yun Liu, Lin Mao, Sixing Xiong, Lulu Sun, Nan Zhao, Fei Qin, Youyu Jiang,

and Yinhua Zhou*

Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic

Information, Huazhong University of Science and Technology, Wuhan 430074, China

*Corresponding author: yh_zhou@hust.edu.cn

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2018

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Experimental Section:

1.1 Materials

The polymer donor poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-

b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-

c’]dithiophene-4,8-dione))] (PBDB-T) and the non-fullerene acceptor 3,9-bis(2-methylene-(3-

(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2’,3’-d’]-

s-indaceno[1,2-b:5,6-b’]dithiophene (ITIC) were purchased from Solarmer Materials Inc. The

zinc acetate dihydrate, monoethanolamine and methoxyethanol for ZnO precursor solutions

were purchased from Sigma-Aldrich. Chlorobenzene (99.5%), branched

polyethyleniminepoly (PEI) and polyethylenimine ethoxylated (PEIE) was also from Sigma-

Aldrich. The monomers indacenodithieno[3,2-b]thiophene (IDTT) and 2-(3-oxo-2,3-

dihydroinden-1-ylidene)malononitrile (INCN) were purchased from Derthon Optoelectronic

Materials Science Technology Co LTD. The acetone and isopropanol were obtained from

Sinopharm Chemical Reagent Co., Ltd.

1.2 Materials and film characterization

For the materials and film characterization, the ITIC and PBDB-T were first dissolved in

chlorobenzene (99.5%) with a concentration of 10 mg/ml, respectively. The solution was

stirred vigorously overnight for use. For the UV-vis-NIR measurement, the films were

fabricated by spin coating the solution onto a quartz substrate at a speed of 1000 rpm. The

PEI or PEIE treated films were processed by exposing the films in a covered Petri dish.

Subsequently, two drops PEI or PEIE solution were dropped in the Petri dish at 160 °C hot

plate for different time. As for the solution, the ITIC and the PEI was mixed directly in

chlorobenzene with various mass ratios. The absorption spectra were recorded on a UV-vis-

NIR spectrophotometer (UV-3600, Shimadzu Scientific Instruments). For the ESR

measurements, films were prepared by drop casting onto quartz substrates. After dry in a N2-

filled glovebox, the resulted films were put into a quartz tube for test. The instrument model

is Bruker ESR A300 and the frequency of the electromagnetic radiation was 9.425 GHZ.

Fourier transform infrared (FT-IR) spectra were collected on a Bruker VERTEX 70 using

potassium bromide (KBr) disks. The nuclear magnetic resonance (NMR) spectra were

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collected on a Bruker AscendTM 600 MHZ NMR spectrometer with deuterated

dichloromethane as the solvent and with tetramethylsilane (δ=0) as the internal standard.

1.3 Solar cells fabrication and characterization

The pre-patterned ITO was first sonicated in baths using detergent in deionized water,

deionized water, acetone, and isopropanol in sequence. Then the prepared ZnO precursor

solutions were spin-coated onto ITO at 4000 rpm for 40 s. The substrate was annealed at 200

oC for 30 min to form a dense metal oxide film. The ZnO precursor solutions were prepared

by adding 0.5 g zinc acetate dihydrate and 0.14 g monoethanolamine in 5 ml methoxyethanol,

and stirring overnight. The PEI and PEIE interlayer was spin-coated on top at 5000 rpm for 1

min from isopropanol solution (0.1 wt.%), respectively. Subsequently, PBDB-T:ITIC (1:1

weight ratio) in a 20 mg/mL chlorobenzene:DIO (99.5:0.5 volume ratio) solution was spin-

coated at 2500 rpm for 60 s. Then, the samples were then transferred into the vacuum

evaporation system. 7 nm MoO3 and 100 nm Ag was evaporated with a metal aperture mask

to complete the device fabrication. Device area is 10.58 mm2. The fabricated devices were

measured under a simulated 100 mW cm−2 AM 1.5G irradiation in a N2-filled glovebox. A

Keithley 2400 was applied to measure the current-voltage characteristics.

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300 600 900 12000.0

0.2

0.4

0.6

0.8

0 min 3 min 5 min 10 min 30 min 1 h

Abso

rban

ce (a

.u.)

Wavelength (nm)

PEIE treated PBDB-T

300 600 900 12000.0

0.2

0.4

0.6

0.8

0 min 3 min 5 min 10 min 30 min 1 h

Abso

rban

ce (a

.u.)

Wavelength (nm)

PEIE treated ITIC(a) (b)

Figure S1. UV-vis-NIR absorption spectra of (a) PBDB-T and (b) ITIC films exposure for

different time in amine vapor from PEIE.

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300 600 900 12000.0

0.2

0.4

0.6

0.8

Abso

rban

ce (a

.u.)

Wavelength (nm)300 600 900 1200

0.0

0.1

0.2

0.3

0.4

Abso

rban

ce (a

.u.)

Wavelength (nm)

IDTT

INCN

(a) (b)

Figure S2. UV-vis-NIR absorption spectra of (a) the IDTT monomer and (b) the INCN

monomer.

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3440 3480 3520 3560 3600-2x106

-1x106

0

1x106

2x106 ITIC ITIC (PEIE treated)

Inte

nsity

(a.u

.)

Magnetic field (Gauss)3200 3300 3400 3500-2x106

-1x106

0

1x106

2x106 PBDB-T PBDB-T (PEI treated) PBDB-T (PEIE treated)

Inte

nsity

(a.u

.)

Magnetic field (Gauss)

(a) (b)

Figure S3. (a) The ESR spectra of pristine ITIC films and corresponding films treated with

amine vapor from PEIE; (b) ESR spectra of pristine PBDB-T films and corresponding films

treated with amine vapor from PEI and PEIE.

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(C=O)

(-CN)ITIC (PEIE treated)

ITIC

3000 2500 2000 1500 1000

(C=O)

(-CN)INCN (PEIE treated)

Wavenumber (cm-1)

INCN

Figure S4. FT-IR spectra of ITIC and INCN monomer as well as the corresponding samples

exposure in amine vapor from PEIE.

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*

#Product 2

Product 1

ITIC

Figure S5. The 1H NMR spectra of pristine ITIC and corresponding products. The reagent is

CD2Cl2.

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3000 2500 2000 1500 1000

(C=O)(CN)

Tran

smitt

ance

(a.u

.)

Wavenumber (cm-1)

ITIC Product 1 Product 2

Figure S6. FT-IR spectra of ITIC and separated products from the reaction of ITIC and

methylamine.