Supporting Information for

A Readily-accessible, Random Perylene Diimide Copolymer Acceptor for All-

polymer Solar Cells

Ping Deng a,b, Bo Wu c, Yanlian Lei c, Dagang Zhou d, Carr Hoi Yi Ho c, Furong Zhu c, Beng S. Ong b,*

a College of Materials Science and Engineering, Fuzhou University, Fuzhou, China.

b Research Centre of Excellence, Institute of Creativity and Department of Chemistry, Hong Kong Baptist University,

Hong Kong SAR, China.

c Department of Physics and Institute of Advanced Materials, Hong Kong Baptist University, Kowloon, Hong Kong

SAR, China d College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, China.

1. Device fabrication and characterization

The experimental all-PSC devices for evaluation have a structural configuration of

ITO/ZnO/PPDI:PTB7-Th/MoO3/Ag as fabricated as follows:

The solution for the active layer was prepared by dissolving appropriate amounts of PPDI and PTB7-Th in

chlorobenzene with or without 1~20 vol % of 1-chloronaphthalene (CN). The solution was spin-coated on ZnO-

coated ITO glass and dried in vacuum oven. After the active layer was completely dried, MoO3 (2 nm) and Ag (100

nm) were thermally deposited under 10-6 Torr as the cathode. The active area of the device was about 9 mm2. The

devices for PCE and EQE measurements were encapsulated in the glove box and measured in ambient conditions. A

SAN-EI XEC-301S solar simulator equipped with a 300 W xenon lamp and an air mass (AM) 1.5G filter was used to

generate a simulated AM 1.5G solar spectrum irradiation source. The irradiation intensity was 100 mW cm −2

calibrated by a standard silicon solar cell VS 0831. A monochromator WDG30 and Bentham DH-Si silicon detector

were used in external quantum efficiency (EQE) measurements.

The SCLC method was applied for hole/electron mobility measurement of active layer films. The hole-only and

electron-only device configurations were respectively ITO/PEDOT:PSS/Blends/Au and ITO/ZnO/Blend/ZnO/Ag.

The carrier mobility was extracted by fitting the current-voltage curves based on the modified Mott-Gurney equation:

J=98

ε ε0 μ ∙ 1L

F2exp (0.89 β √F )

where J is current density, ε is the relative dielectric constant of polymer (ε=3), ε0 is free-space permittivity

(ε0=8.85×10-12 F/m), F is the electric-field in the device (F=V/L), L is the thickness of blend layer, and β is the field

activation factor [1]. The thickness of the polymer blends without CN additive for electron-only device are 99±2 nm

and 102±2 nm, and the thickness of the polymer blends with 10 vol% CN additive for electron-only device are 92±2

nm and 94±2 nm, respectively.

2. Figures

Figure S1. 1H NMR spectrum of the monomer PDI-1.

Figure S2. 1H NMR spectrum of the monomer PDI-2.

Figure S3. 1H NMR spectrum of polymer acceptor PPDI.

Figure S4. TGA plots of PPDI at a heating rate of 10 oC min-1 under N2 atmosphere.

Figure S5. Out of plane X-ray diffraction patterns of a thin film of PPDI:PTB7-Th on silicon wafer substrate.

Figure S6. Chemical structure of PTB7-Th

Figure S7. Current density-voltage curves all-PSC devices with different PPDI:PTB7-Th weight ratios in the active

layers fabricated without CN additive.

Figure S8. Current density−voltage curves of all-PSC devices with PPDI: PTB7-Th active layers (1:1 by weight)

processed with different amounts of CN additive.

3. Tables

Table S1. Molecular weight and thermal properties of PPDI.

Mna[kDa] Mw

a[kDa] PDI Tdb[°C]

11.5 18.7 1.62 452

a Determined by GPC using tetrahydrofuran as an eluent against polystyrene standards. b 5% weight loss

temperature measured by TGA under nitrogen atmosphere.

Table S2. Possible modes of connection of three thiophenes to two PDI units in PPDI.

C2C6&C8C12 C2C6&C2C6 C8C12&C8C12

1,7&1',7'

1,6&1',6'

1,7&1',6'

and／or

(1,6&1',7')

Table S3. Optical and electrochemical properties of polymers PPDI.

λmaxa (nm) λmax

b (nm) Egoptc (eV)

Eoxonset/LUMOd

(V/eV)

HOMOf(eV)

and

490, 555 495, 555 1.74 −0.48/−3.88 −5.62

a Measured in chlorobenzene solution. b Measured as thin film. c Optical band gap, d LUMO = −(Eredonset +

E1/2Fc/Fc+ + 4.8) eV = −(Ered

onset + 4.36)[2,3], f Calculated from the LUMO energy level and optical band gap.

Table S4. Current density-voltage curves and photovoltaic data of all-PSC devices with different PPDI:PTB7-Th

weight ratios in the active layers processed without CN additive.

PPDI:PTB7-Th Voc (V) Jsc (mA cm-2) FF (%) PCE a(%)

1.5:1 0.73 5.00 42.23 1.55 (1.38)

1:1 0.76 5.08 58.60 2.26 (2.20)

1:1.5 0.76 4.66 59.92 2.11 (2.05)

aAverage PCEs given in parentheses.

Table S5. Current density-voltage curves and photovoltaic data of all-PSC devices with PPDI:PTB7-Th active

layers processed with different amounts of CN additive.

Amount of CN Voc (V) Jsc (mA cm-2) FF (%) PCE a(%)

w/o 0.76 5.08 58.60 2.26 (2.20)

3 vol% 0.75 9.91 58.07 4.32 (4.17)

6 vol% 0.74 11.48 62.31 5.29 (5.22)

10 vol% 0.76 11.65 60.33 5.35 (5.30)

20 vol% 0.75 10.85 62.61 5.10 (5.00)

aAverage PCEs given in parentheses.

Table S6. Hole and electron mobility values of PPDI:PTB7-Th active layer (1:1 by weight) by space charge limited

current (SCLC) method.

CN Additive μe(cm2V-1s-1) μh(cm2V-1s-1) μe/μh

without 2.21×10-3 5.10 × 10-4 4.33

10 vol% 2.19×10-3 1.11 × 10-3 1.97

References:

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Macromolecules, 2015, 48, 1759.

[2] P. Deng, L. Liu, S. Ren, H. Li and Q. Zhang, Chem. Commun. 2012, 48, 6960.

[3] P. Deng, B. Wu, Y. Lei, H. Cao and B. S. Ong, Macromolecules, 2016, 49, 2541.