Subtle Side-chain Tuning on Terminal Groups of Small Molecule

Electron Acceptors for Efficient Fullerene-free Polymer Solar Cells

Jie Zhu a,b, Sunsun Li b, Xiaoyu Liu c, Huifeng Yao b, Fenghao Wangb, Shaoqing Zhang c*, Mingliang Sun

a*and Jianhui Hou b*

S1. The extinction coefficients of IT-O1, IT-O2, IT-O3 and IT-O4.

Figure S1. The extinction coefficients of (a) IT-O1, (b) IT-O2, (c) IT-O3 and (d) IT-O4 in chlorobenzene at room

temperature.

Acceptor film extinction coefficients (105 cm-1)

IT-O1 1.33

IT-O2 1.51

IT-O3 1.11

IT-O4 1.00

Table S1. The extinction coefficients as solid thin films of IT-O1, IT-O2, IT-O3 and IT-O4.

0 1 2 3 4 50.0

0.2

0.4

0.6

0.8

1.0

1.2

Ab

so

rba

nc

e

Concentration（10-6 mol cm

-3）

Equation y = a + b*x

Weight No Weighting

Residual Sum

of Squares

5.97321E-6

Pearson's r 0.99999

Adj. R-Square 0.99997

Value Standard Error

B Intercept 0.01761 0.00175

B Slope 0.21571 6.57585E-4

IT-O1

a

0 1 2 3 4 50.0

0.2

0.4

0.6

0.8

1.0

1.2

Ab

so

rba

nc

e

Concentration（10-6 mol cm

-3）

Equation y = a + b*x

Weight No Weighting

Residual Sum

of Squares

5.51074E-5

Pearson's r 0.99995

Adj. R-Square 0.99985

Value Standard Error

D Intercept -0.01123 0.00516

D Slope 0.23058 0.00162

IT-O2

b

0 1 2 3 4 50.0

0.2

0.4

0.6

0.8

1.0

1.2

Ab

so

rba

nc

e

Concentration（10-6 mol cm

-3）

Equation y = a + b*x

Weight No Weighting

Residual Sum

of Squares

1.99322E-5

Pearson's r 0.99998

Adj. R-Square 0.99994

Value Standard Error

F Intercept -0.01222 0.0031

F Slope 0.2148 9.91544E-4

c

IT-O3

0 1 2 3 4 50.0

0.2

0.4

0.6

0.8

1.0

1.2

Ab

so

rba

nc

e

Concentration（10-6 mol cm

-3）

Equation y = a + b*x

Weight No Weighting

Residual Sum

of Squares

3.00481E-5

Pearson's r 0.99997

Adj. R-Square 0.99991

Value Standard Error

H Intercept 0.00358 0.00381

H Slope 0.21957 0.00121

d

IT-O3

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2017

S2. UV-Vis absorption spectra of the materials and PBDB-T blend.

Figure S2. UV–Vis absorption spectra of PBDB-T:IT-O1, PBDB-T:IT-O2 PBDB-T:IT-O3, PBDB-T:IT-O4 blend films.

S3. Theoretical calculations on IT-O1, IT-O2, IT-O3 and IT-O4.

Figure S3. Theoretical calculation results of IT-O1, IT-O2, IT-O3 and IT-O4.

400 500 600 700 800 900

0.0

0.2

0.4

0.6

0.8

1.0

No

rmalized

ab

so

rpti

on

(a.u

.)

Wavelength (nm)

PBDB-T:IT-O1

PBDB-T:IT-O2

PBDB-T:IT-O3

PBDB-T:IT-O4

S4. PL spectra of blend films.

Figure S4. Normalized PL spectra of polymer PBDB-T-based neat film, IT-(O1-O4)-based neat films and the PBDB-T:

IT-(O1-O4)-based blend films. (PBDB-T was excited at 600 nm, all IT-(O1-O4) were excited at 680 nm, all PBDB-T:

IT-(O1-O4)-based blend films were excited at both 680 nm and 600 nm.)

S5. Carrier mobility ofPBDB-T:acceptor blends.

0.0 0.5 1.0 1.5

-2

0

2

4

IT-O1

IT-O2

IT-O3

IT-O4ln(J

) (m

A c

m-2

)

ln(V) (V)

a

100 200 300 400 500 600

-33

-32

-31

-30

-29

IT-O1

IT-O2

IT-O3

IT-O4

Ln

(JL

3/V

2)

(mA

cm

V2

)

(V/L)0.5

(V0.5

cm-0.5

)

b

Figure S5. Plots for the calculation of electron and hole mobilities of PBDB-T:IT-O1, PBDB-T:IT-O1, PBDB-T:IT-O1

and PBDB-T:IT-O4 based blends obtained from the (a) electron-only and (b) hole-only devices.

650 700 750 800 850

0.0

0.2

0.4

0.6

0.8

1.0N

orm

alized

PL

in

ten

sit

y (

a.u

.)

Wavelength (nm)

PBDB-T

IT-O1

Blend 600nm

Blend 680nm

a

650 700 750 800 850

0.0

0.2

0.4

0.6

0.8

1.0

No

rmalized

PL

in

ten

sit

y (

a.u

.)

Wavelength (nm)

PBDB-T

IT-O3

Blend 600nm

Blend 680nm

c

650 700 750 800 850

0.0

0.2

0.4

0.6

0.8

1.0

No

rmalized

PL

in

ten

sit

y (

a.u

.)

Wavelength (nm)

PBDB-T

IT-O4

Blend 600nm

Blend 680nm

d

650 700 750 800 850

0.0

0.2

0.4

0.6

0.8

1.0

No

rmalized

PL

in

ten

sit

y (

a.u

.)

Wavelength (nm)

PBDB-T

IT-O2

Blend 600nm

Blend 680nm

b

S7. NMR spectra of the materials (solvent: CDCl3 (1H NMR: 7.60 ppm, 13C NMR: 77.3 ppm)).

1H NMR spectrum of IN-O1

1H NMR spectrum of DCI-O1

13C NMR spectrum of DCM-O1

1H NMR spectrum of IT-O1

13C NMR spectrum of IT-O1

1H NMR spectrum of IN-O2

1H NMR spectrum of DCI-O2

13C NMR spectrum of DCI-O2

1H NMR spectrum of IT-O2

13C NMR spectrum of IT-O2

1H NMR spectrum of IN-O3

1H NMR spectrum of DCI-O3

13C NMR spectrum of DCI-O3

1H NMR spectrum of IT-O3

13C NMR spectrum of IT-O3

1H NMR spectrum of IN-O4

1H NMR spectrum of DCI-O4

13C NMR spectrum of DCI-O4

1H NMR spectrum of IT-O4

13C NMR spectrum of IT-O4