Supporting Information for

A perylene diimide electron acceptor with a triphenylamine core:

promote photovoltaic performance via hot spin-coating

Juan Hu,a# Xinbin Liu,b# Kangwei Wang,b# Mingliang Wu,a Huaxi Huang,a Di Wu,a,b* Jianlong

Xiaa,b*

aState Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of

Smart Materials and Devices, Wuhan University of Technology No. 122 Luoshi Road, Wuhan

430070, China

bSchool of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology

No. 122 Luoshi Road, Wuhan 430070, China

#These authors contributed equally to this work.

Email: D.W.(chemwd@whut.edu.cn); J.X. (jlxia@whut.edu.cn)

Table of the contents

1. General information

2. Synthesis of acceptor material

3. Thermal Gravimetric Analysis (TGA)

4. UV-vis absorption spectra, photoluminescence (PL) spectra and dynamic light scattering

(DLS) measurement

5. Cyclic voltammetry (CV) curves

6. The photovoltaic performance parameters of the devices

7. Steady photoluminescence quenching experiment

8. X-ray diffraction (XRD) patterns

9. Transmission electron microscope (TEM) images

10. 1H and 13C NMR spectra

11. MALDI-TOF Mass Spectrum

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry C.This journal is © The Royal Society of Chemistry 2019

1. General information

1.1 Materials

All chemical reactions were conducted in oven-dried or flame-dried glassware. All the chemicals

and starting materials were purchased from commercial sources without further treatment unless

specially noted. The commercially available polymer donor PTB7-Th was purchased from Solarmer

Materials Inc. with a MW over 40000 and a PDI of 1.8-2.0. Compounds perylene diimide,1

monobromo-perylene diimide,2 perylene diimide dimer3 and and TPA-3Bpin4 were synthesized

according to literature procedures.

ITO coated glass substrates (a sheet resistance of 15 Ω/sq and a transmittance of 86%) were

purchased from Xiamen Haolu Trading Co., Ltd. ZnAc2·2H2O (99.999% trace metals basis) was

purchased from Sigma-Aldrich. The polymer donor PTB7-Th was purchased from Solarmer

Materials Inc. The small molecule acceptor TPA-3PDI2 was synthesized by our group. The hole

transport layer material MoO3 were purchased from J&K. The electrode material Ag were purchased

from Zhongnuo New Material (Beijing) Technology Co., Ltd. All the chemical solvents utilized in

this work were all purchased from Sigma-Aldrich and used as received without further purification.

1.2 Device fabrication

The inverted devices were fabricated with the architecture of Glass/ITO (135 nm)/ZnO (33

nm)/active layer/MoO3 (8 nm)/Ag (100 nm). The pre-patterned ITO (sheet resistance, 15 Ω/sq)

coated glass substrates were sequentially cleaned with bits of detergent (Alconox Inc.) dissolved in

de-ionized water, twice de-ionized water, acetone and isopropanol in an ultrasonic bath for 20 min,

and then blew dry by high purity nitrogen. The clean substrates were treated by an oxygen plasma

(180 W) for 5 min. The ZnO precursor solution was prepared by dissolving 220 mg ZnAc2·2H2O in

2 mL 2-methoxyethanol and 0.056 mL ethanol amine and then stirred for at least 24h. The solution

was filtered with polyether sulfone (PES, aperture size of 0.45 μm) filter before spin-coating. The

ZnO precursor solution was spin-coated on top of ITO substrate with spinning rate of 5000 rpm for

30 s and annealed at 150 oC for 1 hour in atmospheric air to form a compact ZnO layer. The solution

of PTB7-Th:TPA-3PDI2 (1:1, w/w) was processed through chlorobenzene (CB) with an

concentration of 15 mg mL-1. Then the solution was stirred at 60 oC for overnight to obtain well-

mixed blend solution. Subsequently, the photovoltaic layer was spin-coated with 2000 rpm for 50 s

onto the ZnO layer in a glove box. For the operation of hot spin-coating, before spinning the active

layer, the ZnO coated substrate need be preheated for few minutes on a hot stage within temperature-

controllable spin coater, which can support the continuous heating during the spinning process of

active layer. Eventually, a MoO3 layer and an Ag electrode were sequentially deposited onto the

active layer by thermal evaporation under vacuum at a pressure <1.0×10-4 pa, using a shadow mask

with an effective area of 0.0625 cm2.

1.3 Instruments and characterization

1H and 13C NMR spectra, mass spectrum and CV. 1H NMR and 13C NMR spectra were measured

on Bruker DRX 500 or Varian Mercury plus-400. MALDI-TOF Mass spectrum was measured with

AB Sciex 5800. Cyclic voltammograms (CVs) were obtained on CHI660E electrochemical

workstation. A three-electrode one-compartment cell containing a solution of the analyte and

supporting electrolyte (tetrabutylammonium, ([NBu4]PF6), 0.1M) in CH2Cl2 was utilized. A 500 μm

diameter platinum-disk working electrode, a platinum-wire counter electrode, and an Ag/AgCl

reference electrode were used. Potentials were referenced to the ferrocenium/ferrocene (Fc/Fc+)

couple by using ferrocene as external standards in CH2Cl2 solutions.

TGA. Thermal Gravimetric analysis (TGA) was carried out on an instrument of SDT Q-600 under

a nitrogen atmosphere at a heating rate of 10 oC/min.

Absorption, PL spectra and dynamic light scattering (DLS) measurement. The pure films and

blend films were deposited on quartz glass substrates. The UV-vis absorption spectra of these

samples were evaluated by Shimadzu UV-1800 spectrophotometer, and the PL spectra were

performed on Shimadzu Luminescence Spectrometer RF-6000. The particle size distribution can be

obtained by Dynamic light scattering (DLS) measurement (Nano-ZS ZEN 3600, Malvern Panaco

Instrument Co., Ltd.)

Temperature-controllable spin coater. Temperature-controllable spin coater is purchased by Jiatu

Technology (Jiangyin City, China). The instrument model is IC5000-S.

J-V measurements and EQE spectra. The current-voltage characteristics were conducted under

AM 1.5G illumination at 100 mW/cm2 using an AAA solar simulator (SP94023A-SR1, NewPort).

Before testing, the illumination intensity was calibrated with a standard single-crystal Si

photovoltaic cell (model, 91150V) integrated with a quartz window (model, 1000P072). External

quantum efficiency (EQE) was determined by an EQE system (Zolix, China).

XRD, AFM and TEM images. The blend films were deposited on quartz glass substrates. XRD

measurements were performed using a Rigaku Smart Lab diffractometer under grazing-incidence

diffraction geometry. As radiation source a monochromatic Cu K beam with a wavelength of

λ=0.154 nm was applied. Atomic force microscope images were measured on a Dimension Icon

AFM (Bruker) under tapping mode. Transmission electron microscope (TEM) images were

performed on a JEM-1400plus at an accelerating voltage of 120 kV.

References:

1 Wicklein, A. Lang, M. Muth, M. Thelakkat, J. Am. Chem. Soc., 2009, 131, 14442-14453.

2 P. Rajasingh, R. Cohen, E. Shirman, L. J. W. Shimon, B. Rybtchinski, J. Org. Chem., 2007, 72,

5973-5979.

3 Y. Zhong, M. T. Trinh, R. Chen, W. Wang, P. P. Khlyabich, B. Kumar, Q. Xu, C. Y. Nam, M.

Y. Sfeir, C. Black, M. L. Steigerwald, Y. L. Loo, S. Xiao, F. Ng, X. Y. Zhu, C. Nuckolls, J. Am.

Chem. Soc., 2014, 136, 15215-15221.

4 R. V. Ambili, D. Sasikumar, P. Hridya, M. Hariharan, Chem. Eur. J., 2019, 25, 1992-2002.

2. Synthesis of acceptor material

N

B B

B

O

OO

O

O O

N

N OO

OOR

R

N

N OO

OOR

R

Br +

Pd(PPh3)4 K2CO3

THF/H2O 110 oCM.W. 2h

N

N

O O

O O

R

R

N

N

O O

O O

R

R

N

N

N

O

O

O

O

R

R

N

N

O

O

O

O

R

R

N

N

O

OO

O

R

R N

N

O

OO

O

R

R

R=C6H13

C6H13

PDI2-Br TPA-3PDI2TPA-3Bpin

Scheme S1. Synthetic route of TPA-3PDI2.

To a mixture of monobromo-PDI2 (PDI2-Br, 150 mg, 0.0934 mmol), TPA-3Bpin (16.65 mg, 0.0267

mmol), Tetrakis(triphenylphosphine)palladium(0) (30 mg, 0.026 mmol) and K2CO3 (300 mg),in

microwave tube, degassed THF/H2O (4:1, 20 ml) was added. The reaction was performed by

microwave reactor at 110 oC for 2 hours. After cool down to room temperature, the mixture was

extract with DCM and washed with water. Them the solution was dried over Na2SO4 and

concentrated under reduced pressure. The crude solid was purified by silica gel chromatography

(eluted with petroleum ether/CH2Cl2 from 2:1 to 1:2), further recrystallization with

CH2Cl2/methanol afforded the target molecule TPA-3PDI2 as dark red solid (73 mg, 56.6 %). 1H

NMR (400 MHz, Chloroform-d) δ 10.31 (s, 12H), 9.43 (s, 6H), 9.13 (s, 9H), 9.05 (s, 3H), 8.81 (s,

3H), 7.85 (s, 6H), 7.74 (s, 6H), 5.24 (s, 12H), 2.32 (s, 24H), 1.94 (s, 24H), 1.31 (s, 64H), 1.20 (s,

104H), 1.13–1.10 (m, 24H), 0.77 (s, 60H), 0.67 (s, 12H). 13C NMR (126 MHz, Chloroform-d) δ

164.92, 163.87, 134.01, 130.49, 127.32, 126.93, 126.56, 126.37, 125.78, 124.35, 123.87, 123.46,

122.43, 55.14, 32.51, 31.80, 31.70, 29.30, 29.28, 29.19, 27.07, 26.97, 22.63, 22.61, 22.54, 14.07,

14.05, 13.99. (MALDI-TOF): [TPA-3PDI2+Na]+ calculated for 4851.81, found 4851.83.

3. Thermal Gravimetric Analysis (TGA)

Fig. S1 Thermal Gravimetric analysis (TGA) result of TPA-3PDI2 with a heating rate of 10 oC/min

under nitrogen.

4. UV-Vis absorption spectra, photoluminescence (PL) spectra and dynamic light scattering

(DLS) measurement

Fig. S2 (a) The UV-vis absorption spectra, (b) the Steady photoluminescence spectra in hexane,

chloroform (CF) solution and films of TPA-3PDI2 and (c) particle size distribution of TPA-3PDI2

in hexane with a concentration of 1 × 10-5 M.

5. Cyclic voltammetry (CV) curves

Fig. S3 Cyclic voltammograms (CVs) for TPA-3PDI2 vis (Fc/Fc+).

Table S1. Optical-electrochemical parameters of TPA-3PDI2.

Compound εa/M-1 cm-1 Eredb/V EHOMO

c/eV ELUMOc/eV Eg

d/eV

TPA-3PDI2 1.9 105 (541 nm)× -0.54 -5.58 -3.81 1.77

a ε was determinated in the CHCl3 solutions of a concentration of 5.0 10-6 M. b The reduction ×

potentials were obtained through cyclic voltammetry (CV) method. c The LUMO level was

calculated by the following equations: ELUMO = - (Ered - EFc + 4.8) eV, Ered was obtained from the

onset of reduction, while EFc was the half-wave potential of ferrocene, EHOMO = ELUMO - Eg. d The

optical bandgap was estimated from the onset positions of their absorption spectra and calculated

by the equation: Eg = 1240/λ onset.

6. The photovoltaic parameters of the devices

Table S2. Summary of photovoltaic performance parameters based on different D:A ratios under

the illumination of AM 1.5G at 100 mW/cm2.

PTB7-Th:TPA-3PDI2 Voc (V) Jsc (mA/cm2) FF (%) PCE (%)

1:0.5 0.787±0.007 11.31±0.10 46.85±0.56 4.17±0.07

1:1 0.793±0.006 12.00±0.28 57.79±1.02 5.50±0.05

1:1.5 0.782±0.008 10.20±0.22 60.88±0.74 4.85±0.17

1:2 0.778±0.006 9.19±0.11 60.17±0.91 4.30±0.11

Table S3. Summary of photovoltaic performance parameters based on different thermal annealing

(TA) temperatures under the illumination of AM 1.5G at 100 mW/cm2.

PTB7-Th:TPA-3PDI2 a Voc (V) Jsc (mA/cm2) FF (%) PCE (%)

as cast 0.793±0.006 12.00±0.28 57.79±1.02 5.50±0.05

60 ℃ 0.794±0.006 12.08±0.16 56.15±1.26 5.39±0.17

90 ℃ 0.787±0.006 11.90±0.31 56.25±1.46 5.27±0.27

120 ℃ 0.779±0.008 11.88±0.13 52.63±1.51 4.92±0.16

150 ℃ 0.778±0.008 12.15±0.10 54.15±1.66 5.12±0.14

a The thermal annealing treatment time are 10 minutes for each content.

Table S4. Summary of OSCs photovoltaic performance parameters based on different temperature

of hot spin-coating under the illumination of AM 1.5G at 100 mW/cm2.

PTB7-Th:TPA-3PDI2 Voc (V) Jsc (mA/cm2) FF (%) PCE (%) a

RT 0.793±0.006 12.00±0.28 57.79±1.02 5.50±0.05

40 ℃ 0.795±0.003 11.47±0.19 59.76±0.92 5.45±0.06

50 ℃ 0.792±0.005 12.28±0.26 58.05±2.02 5.65±0.18

60 ℃ 0.790±0.009 14.85±0.33 58.36±0.87 6.85±0.09

70 ℃ 0.783±0.009 13.58±0.15 56.68±1.20 6.02±0.10

80 ℃ 0.785±0.005 14.43±0.09 54.98±0.61 6.23±0.05

100 ℃ 0.781±0.006 14.12±0.14 53.03±0.78 5.84±0.11

a The statistical data presented here were obtained from 5 independent devices for each content.

Fig. S4 The normalized absorption spectra of PTB7-Th:TPA-3PDI2 blend films based on RT

spin-coating and hot spin-coating.

Fig. S5 The dark current curves (Jdark-V) of OSCs based on RT spin-coating and hot spin-coating.

7. Steady photoluminescence quenching experiment

Fig. S6 The steady photoluminescence spectra for the acceptor TPA-3PDI2 film and blend films

with RT spin-coating and hot spin-coating (excited at 530 nm).

Table S5. PL quenching efficiency of the PTB7-Th:TPA-3PDI2 blend films based on RT spin-

coating and hot spin-coating.

PL Quenching efficiency (%)PTB7-Th:TPA-3PDI2

Quenching induced by electron transfer Quenching induced by hole transfer

RT spin-coating 94.8 99.2

Hot spin-coating 95.3 99.4

8. X-ray diffraction (XRD) patterns

Fig. S7 The X-ray diffraction (XRD) patterns of RT and hot spin-coating based blend films.

9. Transmission electron microscope (TEM) images

Fig. S8 The transmission electron microscope (TEM) images of (a) RT spin-coating based blend film and (b) hot spin-coating based blend film.

10. 1H and 13C NMR spectra

Fig. S9 1H NMR spectrum of TPA-3PDI2.

Fig. S10 13C NMR spectrum of TPA-3PDI2.

11. MALDI-TOF Mass Spectrum

4700 4800 4900 5000m/z

TPA-3PDI2-Na+

4851.83

Fig. S11 MALDI-TOF spectrum of TPA-3PDI2.