Fused nonacyclic electron acceptors for efficient polymer solar cells

Article abstract of DOI:10.1021/jacs.6b12755

We design and synthesize four fused-ring electron acceptors based on 6,6,12,12-tetrakis(4-hexylphenyl)-indacenobis(dithieno[3,2-b;2',3'-d]thiophene) as the electron-rich unit and 1,1-dicyanomethylene-3-indanones with 0-2 fluorine substituents as the elect

Full text of DOI:10.1021/jacs.6b12755

Subscriber access provided by Fudan University
Article
Fused Nonacyclic Electron Acceptors for Efficient Polymer Solar Cells
Shuixing Dai, Fuwen Zhao, Qianqian Zhang, Tsz-Ki Lau, Tengfei Li, Kuan
Liu, Qidan Ling, Chunru Wang, Xinhui Lu, Wei You, and Xiaowei Zhan
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.6b12755 • Publication Date (Web): 06 Jan 2017
Downloaded from http://pubs.acs.org on January 6, 2017
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a free service to the research community to expedite the
dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts
appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been
fully peer reviewed, but should not be considered the official version of record. They are accessible to all
readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered
to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published
in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just
Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor
changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers
and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors
or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Journal of the American Chemical Society is published by the American Chemical
Society. 1155 Sixteenth Street N.W., Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 25
Journal of the American Chemical Society
1
2
3
4
5
Fused Nonacyclic Electron Acceptors for Efficient Polymer Solar Cells
6
7
8
9
Shuixing Dai,†,‡ Fuwen Zhao,§ Qianqian Zhang,⊥ TszꢀKi Lau,# Tengfei Li,† Kuan Liu,† Qidan Ling,‡
Chunru Wang,§ Xinhui Lu,# Wei You,⊥ and Xiaowei Zhan†,*
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
† Department of Materials Science and Engineering, College of Engineering, Key Laboratory of
Polymer Chemistry and Physics of Ministry of Education, Peking University, Beijing 100871, China
‡ Fujian Key Laboratory of Polymer Materials, College of Materials Science and Engineering, Fujian
Normal University, Fuzhou 350007, China
§ Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
⊥
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
27599ꢀ3290, United States
# Department of Physics, Chinese University of Hong Kong, New Territories, Hong Kong, China
1
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 2 of 25
1
2
3
4
5
6
7
8
9
ABSTRACT: We design and synthesize four fusedꢀring electron acceptors based on
6,6,12,12ꢀtetrakis(4ꢀhexylphenyl)ꢀindacenobis(dithieno[3,2ꢀb;2',3'ꢀd]thiophene) as the electronꢀrich
unit and 1,1ꢀdicyanomethyleneꢀ3ꢀindanones with 0 to 2 fluorine substituents as the electronꢀdeficient
units. These four molecules exhibit broad (550–850 nm) and strong absorption with high extinction
coefficients of (2.1ꢀ2.5) × 105 M–1 cm–1. Fluorine substitution down shifts LUMO energy level, red
shift absorption spectrum, and enhance electron mobility. The polymer solar cells based on the
fluorinated electron acceptors exhibit power conversion efficiencies as high as 11.5%, much higher
than that of their nonfluorinated counterpart (7.7%). We investigate the effects of the fluorine atom
number and position on electronic properties, charge transport, film morphology, and photovoltaic
properties.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Keywords: indacenobis(dithienothiophene); fusedꢀring electron acceptor; nonfullerene acceptor;
fluorinated acceptor; polymer solar cell
2
ACS Paragon Plus Environment

Page 3 of 25
Journal of the American Chemical Society
1
2
3
4
■ INTRODUCTION
5
6
7
8
9
Organic solar cells (OSCs) are considered to be one of promising alternatives to siliconꢀbased solar
cells since they present unique features, such as low processing cost, semiꢀtransparency, flexibility,
and light weight.1ꢀ3 For a long period of time, OSCs mainly employed fullerene derivatives (e.g.,
PC61BM and PC71BM) as electron acceptors which, paired with electron donating polymers or small
molecules, have successfully achieved power conversion efficiencies (PCEs) over 11%.4ꢀ7 However,
fullerene derivatives suffer from several shortcomings, such as poor absorption in the visible region,
limited tunability of energy levels, and morphology instability, which hinder the further development
of OSCs. On the other hand, nonfullerene electron acceptors possess advantages over their fullerene
counterpart, such as enhanced absorption in the visible and even near infrared (NIR) region, tunable
energy levels, good device stability, and easy synthesis and purification. For all these reasons, rapid
progress has been made with these nonfullerene electron acceptors, which have led to impressive
PCEs.8ꢀ35
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Recently, indacenodithiophene (IDT) and indacenodithieno[3,2ꢀb]thiophene (IDTT)ꢀbased
fusedꢀring electron acceptors (FREAs) have attracted considerable attention.36ꢀ51 These FREAs
exhibit broad and strong absorption, suitable lowest unoccupied molecular orbital (LUMO) and
highest occupied molecular orbital (HOMO) energy levels, and high electron mobility. OSCs based
on these FREAs have exhibited high PCEs with small energy loss51 and good device stability.37 Most
of these FREAs, such as ITIC,36 ITICꢀTh37 and IDIC,38,48 are based on IDT or IDTT donor unit and
1,1ꢀdicyanomethyleneꢀ3ꢀindanone (IC) acceptor unit.
3
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 4 of 25
1
2
3
4
5
6
7
8
9
In this work, we design and synthesize an electronꢀrich unit 6,6,12,12ꢀtetrakis(4ꢀhexylphenyl)ꢀ
indacenobis(dithieno[3,2ꢀb;2',3'ꢀd]thiophene) (IBDT) and three electronꢀdeficient units fluorinated
IC, to construct a small library of four FREAs (INIC series) based on IBDT endꢀcapped with IC or
fluorinated IC (Chart 1, Scheme 1). Our molecular design rationale is as follows. First, IBDT has
larger rigid and coplanar structure and stronger electronꢀdonating ability than IDT and IDTT, both of
which are beneficial to enhancing the absorption and charge transport. Second, fluorinated IC has
stronger electronꢀwithdrawing ability than IC due to strong electronegativity of fluorine atom, and
promotes intermolecular interactions through forming nonꢀcovalent FꢀS and FꢀH bonds, which is
favorable for charge transport.52ꢀ54 Third, “acceptor−donor−acceptor” structure in INIC series can
induce intramolecular charge transfer and lead to broad and strong absorption throughout the visible
and even NIR region (500−850 nm). Indeed, our results show that fluorinated INIC exhibit lower
energy levels, redꢀshifted absorption, and higher electron mobility than nonfluorinated INIC.
Furthermore, nonfullerene OSCs based on fluorinated INIC electron acceptor and a wideꢀbandgap
polymer donor FTAZ55 (Chart 1) exhibit PCEs as high as 11.5%, significantly higher than that of
nonfluorinated INIC (7.7%). More importantly, with this series, we are able to investigate the effects
of the number of fluorine atoms and their positions on electronic properties, charge transport, film
morphology, and photovoltaic properties.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
4
ACS Paragon Plus Environment

Page 5 of 25
Journal of the American Chemical Society
1
2
3
4
C6H13
C6H13
C6H13
C6H13
F
5
6
7
8
O
S
CN
O
S
CN
S
S
S
S
NC
CN
NC
NC
NC
S
S
S
S
NC
S
S
O
O
9
F
C6H13
C6H13
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
C6H13
C6H13
INIC
INIC1
C6H13
S
F
F
F
C6H13
C6H13
C6H13
O
S
O
CN
CN
S
S
S
S
NC
NC
NC
NC
NC
NC
S
S
S
S
S
S
O
O
C6H13
C6H13
C6H13
C6H13
F
F
F
INIC3
INIC2
C4H9
N
C6H13 C4H9
C6H13
N
N
S
S
S
S
n
F
F
C4H9 C6H13
FTAZ
Chart 1. Chemical structures of INIC series and FTAZ.
■ RESULTS AND DISCUSSION
Synthesis and Characterization. The fluorinated IC moieties (2, 4 and 7) were synthesized
from corresponding monofluorinated or difluorinated indanedione (1, 3, 6) and malononitrile
(Scheme 1). Compound 4 is a mixture of two isomer, which was difficult to separate. Thus we used
them together for the final condensation reaction without separation. Stille coupling reaction between
compounds 8 and 9 with Pd(PPh3)4 catalyst yielded compound 10. A double nucleophilic addition of
(4ꢀhexylphenyl)magnesium bromide to the ester groups in 10, followed by intramolecular cyclization
via acidꢀmediated Friedel−Crafts reaction afforded IBDT (11). Compound 11 was lithiated by
nꢀbutyllithium in THF solution at －78 °C, then quenched by dry DMF to afford aldehyde 12. INIC,
5
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 6 of 25
1
2
3
4
5
6
7
8
9
INIC1, INIC2 and INIC3 were synthesized using Knoevenagel condensation reactions between IC, 2,
4, 7 and aldehyde 12, respectively. The new compounds were fully characterized by spectroscopic
methods and elemental analysis (see Supporting Information).
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
The four INIC series compounds exhibit good solubility in organic solvents, such as chloroform
(CF) and oꢀdichlorobenzene (DCB). The thermal stability of these four molecules was investigated
using thermogravimetric analysis (TGA) (Figure S1, Supporting Information). The TGA curves of
four compounds show decomposition temperatures (Td, 5% weight loss) varying from 302 °C to 342
°C, which indicate good thermal stability.
The UVꢀvis absorption spectra of INIC, INIC1, INIC2 and INIC3 were measured in chloroform
solution and thin film. In solution, four molecules show similar absorption spectra shapes with peaks
from 692 nm to 710 nm (Figure 1a), and similar molar extinction coefficients from 2.1 × 105 M–1
cm–1 to 2.5 × 105 M–1 cm–1 at maximum absorption peaks (Table 1). In thin films, all four molecules
show redꢀshifted and broader absorption spectra than their solutions. The absorption peaks of these
four compounds red shift gradually from 706 nm to 744 nm (Figure 1b). Fluorination redꢀshifts the
absorption of INIC: INIC2 with F at metaꢀposition exhibits redꢀshifted absorption relative to INIC1
with F at orthoꢀposition, and INIC3 with two F atoms exhibits redꢀshifted absorption relative to
INIC1 and INIC2 with one F atom. The optical bandgaps of INIC, INIC1, INIC2 and INIC3 are
calculated to be 1.57, 1.56, 1.52 and 1.48 eV from the absorption edge, respectively (Table 1).
Cyclic voltammetry (CV) was employed to investigate the electrochemical properties of INIC,
INIC1, INIC2 and INIC3 (Figure 1c). Four compounds exhibit irreversible reduction waves and
quasiꢀreversible oxidation waves. The HOMO and LUMO energy levels are calculated from the
6
ACS Paragon Plus Environment

Page 7 of 25
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
onset oxidation and reduction potentials, assuming the absolute energy level of FeCp2+/0 to be 4.8 eV
below vacuum. The HOMO levels of INIC, INIC1, INIC2 and INIC3 are estimated to be –5.45 eV to
–5.54 eV and LUMO levels are –3.88 eV to –4.02 eV (Figure 1d, Table 1). The fluorination
downꢀshifts the molecular HOMO and LUMO levels. Specifically, INIC3 with two fluorines has
lower LUMO level than INIC1 and INIC2 with one fluorine, whereas three fluorineꢀmodified
molecules show similar HOMO levels. The bandgap of INIC, INIC1, INIC2 and INIC3 estimated
from the CV data is 1.57, 1.57, 1.54, and 1.50 eV, respectively, similar to the optical bandgaps.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
7
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 8 of 25
1
2
3
4
5
6
7
8
9
NC
NC
O
O
O
O
NC CN , NaOAc
EtOH, 35.8%
F
F
1
2
NC
NC
NC
NC
NC
NC
O
O
O
O
NC CN , NaOAc
EtOH, 57.5%
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
F
F
F
F
(29%)
(71%)
3
4
NC
NC
O
O
O
O
O
O
O
O
NC CN , NaOAc
EtOH, 46.6%
O
Ac2O, Et3N, 43.4%
F
F
F
F
F
F
5
6
9
7
EtOOC
S
EtOOC
Br
S
S
S
Pd(PPh3)4, toluene
110 oC, 71.3%
Br
Sn(C4H9)3
S
S
S
S
S
COOEt
COOEt
8
10
C6H13
C6H13
C6H13
C6H13
BrMg
C6H13
1)
S
S
n-BuLi, DMF
S
S
THF, reflux
S
S
CHO
S
S
THF, -78 oC, 67%
S
OHC
S
S
2)
S
H2SO4 , CH3COOH
octane, 34.8%
C6H13
C6H13
C6H13
C6H13
11
12
NC
NC
O
74.6%
47.5%
INIC
INIC1
2
pyridine
CHCl3, 65 o
12
C
48.8%
45.5%
4
7
INIC2
INIC3
Scheme 1. Synthetic Routes for INIC, INIC1, INIC2 and INIC3.
a)
b)
Solution
Film
INIC
INIC1
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
INIC
INIC1
INIC
INIC
2
3
INIC
INIC
2
3
400
500
600
700
800
400
500
600
700
800
900
Wavelength (nm)
Wavelength (nm)
8
ACS Paragon Plus Environment

Page 9 of 25
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
0.8
c)
d)
-3.0
-3.5
-4.0
-4.5
-5.0
-5.5
-3.17
INIC
0.6
INIC1
0.4
-3.88
-5.45
-3.97
-5.54
-3.98
-5.52
-4.02
-5.52
0.2
INIC2
0.0
INIC3
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
-0.2
-0.4
+/0
FeCp
2
0.2 mA
-0.5
-5.38
0.0
0.5
1.0
1.5
1
2
3
4
5
6
Potential (V)
Figure 1. (a) UVꢀvis absorption spectra of INIC, INIC1, INIC2 and INIC3 in chloroform and (b) as a
thin film; (c) cyclic voltammograms for INIC, INIC1, INIC2 and INIC3 and (d) energy levels for
FTAZ, INIC, INIC1, INIC2 and INIC3.
Table 1. Absorption and Energy Levels of INIC, INIC1, INIC2 and INIC3
a
opt e
cv h
Eg
HOMOf LUMOg Eg
b
c
d
Td
λs, max
(nm)
692
λf, max
(nm)
706
εmax
compound
(oC)
311
302
342
327
(M–1 cm–1)
2.1 × 105
2.2 × 105
2.1 × 105
2.5 × 105
(eV)
1.57
1.56
1.52
1.48
(eV)
–5.45
–5.54
–5.52
–5.52
(eV)
–3.88
–3.97
–3.98
–4.02
(eV)
1.57
1.57
1.54
1.50
INIC
INIC1
INIC2
INIC3
710
720
704
728
710
744
aThe decomposition temperature measured from TGA. bAbsorption maximum in solution.
cAbsorption maximum in film. Molar extinction coefficient at λmax in solution. Optical bandgap
d
e
f
calculated from the absorption edge of thin film. HOMO energy level estimated from the onset
oxidation potential. gLUMO energy level estimated from the onset reduction potential.
hHOMO–LUMO gap estimated from CV.
9
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 10 of 25
1
2
3
4
5
6
7
8
9
The electron mobilities of four compounds were measured using the space chargeꢀlimited
current (SCLC) method (Figure S2). The electron mobilities of INIC, INIC1, INIC2 and INIC3 are
6.1 × 10–5, 1.0 × 10–4, 1.2 × 10–4 and 1.7 × 10–4 cm2 V–1 s–1, respectively (Table S1). Fluorinated
compounds, particularly difluorinated INIC3, exhibit higher mobility.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Photovoltaic Properties. Our previously reported wideꢀbandgap (2.00 eV) polymer donor FTAZ
exhibits strong absorption at 400ꢀ620 nm with a molar extinction coefficient of 9.8 × 104 M–1 cm–1,
which is complementary with absorption of INIC series (Figure S3).55 The energy levels of FTAZ
(HOMO = −5.38 eV; LUMO = −3.17 eV) match with those of INIC series (Figure 1d). FTAZ
exhibits a high hole mobility of 1.2 × 10–3 cm2 V−1 s−1,56 matching with those of INIC series (Table
S1). Thus, we used FTAZ as a donor and INIC series as acceptors to fabricate bulk heterojunction
(BHJ) OSCs with a structure of indium tin oxide (ITO)/ZnO/FTAZ:acceptor/MoOx/Ag. The
optimized FTAZ/acceptor weight ratio is 1:1.5 (Table S2). The optimized 1,8ꢀdiiodooctane (DIO)
content is 0.25% DIO (v/v) (Table S3). Table 2 summarizes the open circuit voltage (VOC), short
circuit current density (JSC), fill factor (FF), and PCE of the optimized devices. The current
density–voltage (J–V) curves of the best PSCs are shown in Figure 2a.
Fluorination of INIC decreases average VOC of OSCs from 0.957 V to 0.857 V, which is
consistent with the trend of lowering LUMO by fluorination in INIC series. The OSCs based on
nonfluorinated INIC show average JSC value of 13.51 mA cm–2, while fluorination of INIC enhances
average JSC to 16.63ꢀ19.44 mA cm–2. In particular, the OSCs based on difluorinated INIC3 show the
highest JSC of 19.68 mA cm–2. The trend in fill factor (FF) is similar to that in JSC. The OSCs based
10
ACS Paragon Plus Environment

Page 11 of 25
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
on nonfluorinated INIC show average FF value of 57.9%, while fluorination of INIC enhances
average FF to 64.3%ꢀ67.4%. In particular, the OSCs based on difluorinated INIC3 show the highest
FF of 68.5%. The best PCE of the OSCs based on nonfluorinated INIC is 7.7%, while the best PCE
of the OSCs based on monofluorinated INIC1 and INIC2 is 10.1% and 10.8%, respectively. The
OSCs based on difluorinated INIC3 show the best performance: VOC of 0.852 V, JSC of 19.68 mA
cm–2, FF of 68.5%, and PCE of 11.5%. Clearly, fluorination of INIC significantly enhances the
performance of nonfullerene OSCs. The photon energy loss (Eloss) is calculated using the formula
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
E
loss = Eg－eVOC.57,58 The Eloss values of the OSCs are 0.61ꢀ0.63 eV, which are relatively small.
Table 2. Performance of the optimized OSCs based on FTAZ: acceptor.
JSC
(mA
PCE (%)
calculated
JSC
Eloss
VOC
FF
devicea
(eV)
(V)
(%)
best average b
cm–2)
(mA cm–2)
FTAZ: INIC
FTAZ: INIC1
FTAZ: INIC2
FTAZ: INIC3
0.957±0.006
0.929±0.003
0.903±0.004
0.857±0.003
13.51±0.18 57.9±1.3
7.7
7.5
9.9
13.00
0.61
0.63
0.62
0.62
16.63±0.06 64.3±0.4 10.1
17.56±0.20 66.8±0.9 10.8
19.44±0.24 67.4±1.0 11.5
15.93
10.6
11.2
17.17
19.13
a FTAZ/acceptor = 1:1.5 (w/w), 0.25% DIO (v/v). bAverage PCEs are obtained from 10 devices.
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
a)
3
0
80
70
60
50
40
30
20
10
0
b)
INIC
-3
INIC1
INIC2
INIC3
-6
-9
INIC
-12
-15
-18
-21
INIC1
INIC2
INIC3
0.0
0.2
0.4
0.6
0.8
1.0
300
400
500
600
700
800
Voltage (V)
Wavelength (nm)
11
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 12 of 25
1
2
3
4
5
6
d)
10
c)
10
7
8
9
INIC
INIC1
1
INIC
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
INIC1
INIC2
INIC3
INIC2
INIC3
J
J
1
0.1
0.1
1
1
10
100
-2
V
(V)
Light Intensity (mW cm
)
eff
Figure 2. (a) J–V characteristics and (b) EQE spectra of the best OSCs under illumination of an AM
1.5 G at 100 mW cm–2, (c) Jph versus Veff characteristics and (d) JSC versus light intensity of the
optimized devices.
The external quantum efficiency (EQE) spectra of the optimized devices are shown in Figure 2b.
The OSCs based on these four INIC acceptors show broad photoresponse extending from 300 to 850
nm. The maximum EQE values of INIC, INIC1, INIC2 and INIC3ꢀbased devices are 62.6%, 71.5%,
75.8 and 77.0%, respectively, indicating efficient charge generation and collection. In the NIR region,
the IPCE spectra are broadened and enhanced gradually from INIC to INIC1, INIC2 and INIC3,
resembling the absorption profile of the four INIC acceptors in the NIR region (Figure 1b). The JSC
values of INIC, INIC1, INIC2 and INIC3ꢀbased devices calculated from integration of the EQE
spectra with the AM 1.5G reference spectrum are 13.00, 15.93, 17.17 and 19.13 mA cm–2,
respectively, which are in good agreement with JSC values measured from J–V (the error is < 5%,
Table 2).
To probe the exciton/charge dynamics, we measured the photocurrent density (Jph) versus the
effective voltage (Veff) to study the charge generation, dissociation and extraction properties. Jph is
12
ACS Paragon Plus Environment

Page 13 of 25
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
defined as JL – JD, where JL and JD are the photocurrent densities under illumination and in the dark,
respectively. Veff is defined as V0 –Vbias, where V0 is the voltage at which photocurrent is zero and
Vbias is the applied voltage bias. In Figure 2c, Jph reaches saturation (Jsat) at 2 V, suggesting the
charge recombination reach the minimal level and all the charge are collected by the electrodes. The
charge dissociation probability (P(E, T)) can be calculated from Jph/Jsat. Under shortꢀcircuit condition,
the P(E, T) of INIC, INIC1, INIC2 and INIC3ꢀbased OSCs are 94.5%, 94.1%, 94.2% and 95.5%,
respectively, indicating efficient charge dissociation and collection for all four INIC based OSCs.
We also measured the JSC versus light density (P) curves to study charge recombination
behavior (Figure 2d). The relationship between JSC and P can be described as Jsc ∝ Pα.59 If all the
charges are swept out and collected by the electrode before recombination, α should be equal to 1,
while α < 1 means the existence of charge recombination. The α values of INIC, INIC1, INIC2 and
INIC3ꢀbased OSCs are 0.983, 0.976, 0.981 and 0.98, respectively, suggesting negligible bimolecular
charge recombination at the short circuit condition.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
The hole mobility and electron mobility of the four blended films were measured using the
SCLC method (Figure S4). The FTAZ: fluorinated INIC blends exhibit higher electron mobility than
the FTAZ: INIC blend (Table S4), resembling the trend in pure INIC series (Table S1). Since hole
mobilities of all the blended films are similar (1.8 × 10–4 to 3.0 × 10–4 cm2 V–1 s–1), the FTAZ: INIC
blend shows unbalanced charge transport (ꢀh
/ꢀe = 13), while the FTAZ: fluorinated INIC blends
show more balanced charge transport (ꢀh ꢀe = 1.4 to 2.4). Thus, the higher electron mobility and
/
more balanced charge transport in the FTAZ: fluorinated INIC blends are one of the reasons for the
higher JSC and higher FF in these fluorinated INICꢀbased devices (Table 2).
13
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 14 of 25
1
2
3
4
5
6
7
Film Morphology and Microstructure
8
9
To understand the active layer morphology, we first used atomic force microscope (AFM) to
obtain the height and phase images of these four active layers (Figure S5). All four active layers (thin
films) exhibit smooth surface morphology with a rootꢀmeanꢀsquare (RMS) roughness of 0.54ꢀ0.9 nm.
We next employed grazingꢀincidence wideꢀangle and smallꢀangle Xꢀray scattering (GIWAXS and
GISAXS) measurements to probe the bulk morphology of these thin films.60,61 Figure 3a shows 2D
GIWAXS patterns of FTAZ:INIC, FTAZ:INIC1, FTAZ:INIC2, FTAZ:INIC3 thin films. The films
of FTAZ:INIC, FTAZ:INIC1, FTAZ:INIC2 exhibit preferential “faceꢀon” oriented molecular
packing with the lamellar peak located at qr ≈ 0.32 Åꢀ1 and the π–π peak located at qz ≈ 1.7 Åꢀ1
(Figure 3b), which agree with the corresponding peak positions of pure FTAZ (Figure S6), indicating
that the mixing of FTAZ and INIC/INIC1/INIC2 preserves the favorable “faceꢀon” oriented FTAZ
semiꢀcrystalline domains. Interestingly, the GIWAXS pattern of FTAZ:INIC3 is dramatically
different: the faceꢀon oriented domains present a sharp lamella peak at qr ≈ 0.29 Åꢀ1 and a π–π peak
at qz ≈1.84 Åꢀ1, agreeing with the corresponding lattice constants of pure INIC3 (Figure S6).
Therefore, the lamella peak appearing at qz = 0.42 Åꢀ1, clearly visible in the outꢀofꢀplane direction
(Figure 3b, right), should be assigned to “edgeꢀon” oriented FTAZ domains. Notice that the lattice
constant of FTAZ shrinks a lot (d = 2π/q = 15.0 Å) compared with that of other films (d = 19.6 Å),
indicating that the coꢀcrystallization of FTAZ and INIC3 leads to a tighter packing of FTAZ. Thus,
FTAZ/INIC3 blend films not only exhibit highest crystallinity compared with other three
counterparts, but also maintain both FTAZ and INIC3 semiꢀcrystalline packings. Although FTAZ
14
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
ACS Paragon Plus Environment

Page 15 of 25
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
domains reorient into relatively unfavorable “edgeꢀon” orientation, INIC3 domains remain in the
favorable “faceꢀon” orientation. This is consistent with the highest electron mobility and more
balanced electron and hole mobility observed in the FTAZ/INIC3 blend film.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 3c and Figure S7 present 2D GISAXS patterns, GISAXS intensity profiles and best
fittings along the inꢀplane direction of pure FTAZ, pure acceptors and the FTAZ:acceptor blends. We
adopt the DebyeꢀAndersonꢀBrumberger (DAB) model, a polydispersed hard sphere model and a
fractalꢀlike network model61 to account for the scattering contribution from intermixing amorphous
phases, FTAZ domains and acceptor domains, respectively. The FTAZ domains remain the same for
the four blends (~4.5 nm) and the acceptor domains are 15.6 nm, 14.5 nm, 23.1 nm, 17.6 nm for
INIC, INIC1, INIC2, INIC3, respectively. The correlation lengths of the intermixing phase are 32.6
nm, 27.0 nm, 39.0 nm, 42.0 nm for FTAZ:INIC, FTAZ:INIC1, FTAZ:INIC2, FTAZ:INIC3,
respectively. These results suggest that the nanoscale phase separation of all four films is in a
reasonable range for efficient exciton dissociation. The stronger crystallinity of INIC3 doesn’t lead to
undesirable micron size aggregation as observed in some small molecule acceptors with strong
crystallinity.62
15
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 16 of 25
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 3. a) 2D GIWAXS patterns. b) The corresponding GIWAXS intensity profiles along the
inꢀplane (left) and outꢀofꢀplane (right) directions. c) The GISAXS intensity profiles and best fittings
along the inꢀplane direction.
16
ACS Paragon Plus Environment

Page 17 of 25
Journal of the American Chemical Society
1
2
3
4
■ CONCLUSIONS
5
6
7
8
9
In summary, four new fusedꢀring electron acceptors (FREAs), INIC, INIC1, INIC2 and INIC3,
based on a fusedꢀnonacyclic IBDT core endꢀcapped with nonfluorinated or fluorinated IC were
designed and synthesized for application in nonfullerene OSCs. These four molecules have strong
absorption in the visible and even nearꢀinfrared region with high extinction coefficients of 2.1ꢀ2.5 ×
105 M–1 cm–1. Three fluorinated molecules INIC1, INIC2, and INIC3 show redꢀshifted absorption
and lower HOMO/LUMO energy levels relative to the nonfluorinated INIC due to
electronꢀwithdrawing property of fluorine. The fluorinated molecules, particularly the difluorinated
INIC3, have higher electron mobilities than INIC without fluorine substitution. FTAZ/INIC3 blend
films not only exhibit highest crystallinity compared with other three counterparts, but also maintain
both FTAZ and INIC3 semiꢀcrystalline packings, possibly due to fluorineꢀinduced intermolecular
interactions. This is the main reason for the highest electron mobility and more balanced electron and
hole mobility observed in the FTAZ/INIC3 blend film. The nanoscale phase separation of all the
films is in a reasonable range for efficient exciton dissociation, and the stronger crystallinity of
INIC3 doesn’t lead to undesirable micron size aggregation. Since the wideꢀbandgap polymer donor
FTAZ and the narrowꢀbandgap INIC series acceptors exhibit complementary absorption, matched
energy levels and matched mobility, the nonfullerene OSCs based on FTAZ:INIC series blends
exhibit small energy loss of 0.61ꢀ0.63 eV, yet efficient charge dissociation and collection, negligible
bimolecular charge recombination, and finally high PCEs of 7.7ꢀ11.5%. Fluorination of INIC
significantly enhances the PCE from 7.7% to >10%, in particular, the OSCs based on difluorinated
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
17
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 18 of 25
1
2
3
4
5
6
INIC3 show the best PCE of 11.5%. These results demonstrate the great potential of the new IBDT
and fluorinated IC building blocks for constructing highꢀperformance nonfullerene acceptors.
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
■ ASSOCIATED CONTENT
Supporting Information
Detailed experimental procedures including synthesis, characterization and device fabrication, and
additional characterization data, such as TGA, SCLC, AFM, GIWAXS and GISAXS. These materials
are available free of charge via the Internet at http://pubs.acs.org.
■ AUTHOR INFORMATION
Corresponding Author
* Eꢀmail: xwzhan@pku.edu.cn
Notes
The authors declare no competing financial interest.
■ ACKNOWLEDGMENT
X.Z. wish to thank the 973 Program (No. 2013CB834702) and the NSFC (No. 91433114). T.L.
and X.L. acknowledge the financial support from RGC of Hong Kong GRF (No. 14303314) and
CUHK Direct Grant (no. 4053128). Q.Z., and W.Y. were supported by the Office of Naval Research
(No. N000141410221) and NSF (No. DMRꢀ1507249).
■ REFERENCES
(1) Cheng, Y. J.; Yang, S. H.; Hsu, C. S. Chem. Rev. 2009, 109, 5868.
(2) Lu, L.; Zheng, T.; Wu, Q.; Schneider, A. M.; Zhao, D.; Yu, L. Chem. Rev. 2015, 115, 12666.
18
ACS Paragon Plus Environment

Page 19 of 25
Journal of the American Chemical Society
1
2
3
4
(3) Lin, Y.; Zhan, X. Acc. Chem. Res. 2016, 49, 175.
5
6
7
8
9
(4) Chen, C.ꢀC.; Chang, W.ꢀH.; Yoshimura, K.; Ohya, K.; You, J.; Gao, J.; Hong, Z.; Yang, Y.
Adv. Mater. 2014, 26, 5670.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(5) Zhou, H.; Zhang, Y.; Mai, C. K.; Collins, S. D.; Bazan, G. C.; Nguyen, T. Q.; Heeger, A. J.
Adv. Mater. 2015, 27, 1767.
(6) Zhao, J.; Li, Y.; Yang, G.; Jiang, K.; Lin, H.; Ade, H.; Ma, W.; Yan, H. Nat. Energy 2016, 1,
15027.
(7) Li, M.; Gao, K.; Wan, X.; Zhang, Q.; Kan, B.; Xia, R.; Liu, F.; Yang, X.; Feng, H.; Ni, W.;
Wang, Y.; Peng, J.; Zhang, H.; Liang, Z.; Yip, H.ꢀL.; Peng, X.; Cao, Y.; Chen, Y. Nat. Photon. 2016,
DOI: 10.1038/nphoton.2016.240.
(8) Zhan, X.; Facchetti, A.; Barlow, S.; Marks, T. J.; Ratner, M. A.; Wasielewski, M. R.; Marder,
S. R. Adv. Mater. 2011, 23, 268.
(9) Lin, Y.; Zhan, X. Mater. Horiz. 2014, 1, 470.
(10)Zhong, Y.; Trinh, M. T.; Chen, R.; Purdum, G. E.; Khlyabich, P. P.; Sezen, M.; Oh, S.; Zhu,
H.; Fowler, B.; Zhang, B.; Wang, W.; Nam, C. Y.; Sfeir, M. Y.; Black, C. T.; Steigerwald, M. L.; Loo,
Y. L.; Ng, F.; Zhu, X. Y.; Nuckolls, C. Nat. Commun. 2015, 6, 8242.
(11)Zhong, Y.; Trinh, M. T.; Chen, R.; Wang, W.; Khlyabich, P. P.; Kumar, B.; Xu, Q.; Nam,
C.ꢀY.; Sfeir, M. Y.; Black, C.; Steigerwald, M. L.; Loo, Y.ꢀL.; Xiao, S.; Ng, F.; Zhu, X. Y.; Nuckolls,
C. J. Am. Chem. Soc. 2014, 136, 15215.
(12)Wu, Q.; Zhao, D.; Schneider, A. M.; Chen, W.; Yu, L. J. Am. Chem. Soc. 2016, 138, 7248.
(13)Meng, D.; Sun, D.; Zhong, C.; Liu, T.; Fan, B.; Huo, L.; Li, Y.; Jiang, W.; Choi, H.; Kim, T.;
19
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 20 of 25
1
2
3
4
5
6
7
8
9
Kim, J. Y.; Sun, Y.; Wang, Z.; Heeger, A. J. J. Am. Chem. Soc. 2016, 138, 375.
(14)Meng, D.; Fu, H.; Xiao, C.; Meng, X.; Winands, T.; Ma, W.; Wei, W.; Fan, B.; Huo, L.;
Doltsinis, N. L.; Li, Y.; Sun, Y.; Wang, Z. J. Am. Chem. Soc. 2016, 138, 10184.
(15)Sun, D.; Meng, D.; Cai, Y.; Fan, B.; Li, Y.; Jiang, W.; Huo, L.; Sun, Y.; Wang, Z. J. Am.
Chem. Soc. 2015, 137, 11156.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(16)Lee, J.; Singh, R.; Sin, D. H.; Kim, H. G.; Song, K. C.; Cho, K. Adv. Mater. 2016, 28, 69.
(17)Zhong, H.; Wu, C.ꢀH.; Li, C.ꢀZ.; Carpenter, J.; Chueh, C.ꢀC.; Chen, J.ꢀY.; Ade, H.; Jen, A. K.
Y. Adv. Mater. 2016, 28, 951.
(18)Lin, H.; Chen, S.; Hu, H.; Zhang, L.; Ma, T.; Lai, J. Y.; Li, Z.; Qin, A.; Huang, X.; Tang, B.;
Yan, H. Adv. Mater. 2016, 28, 8546.
(19)Liu, Y.; Mu, C.; Jiang, K.; Zhao, J.; Li, Y.; Zhang, L.; Li, Z.; Lai, J. Y.; Hu, H.; Ma, T.; Hu,
R.; Yu, D.; Huang, X.; Tang, B. Z.; Yan, H. Adv. Mater. 2015, 27, 1015.
(20)Liu, J.; Chen, S.; Qian, D.; Gautam, B.; Yang, G.; Zhao, J.; Bergqvist, J.; Zhang, F.; Ma, W.;
Ade, H.; Inganäs, O.; Gundogdu, K.; Gao, F.; Yan, H. Nat. Energy 2016, 1, 16089.
(21)Zhang, X.; Lu, Z.; Ye, L.; Zhan, C.; Hou, J.; Zhang, S.; Jiang, B.; Zhao, Y.; Huang, J.; Zhang,
S.; Liu, Y.; Shi, Q.; Liu, Y.; Yao, J. Adv. Mater. 2013, 25, 5791.
(22)Zhan, X.; Tan, Z. a.; Domercq, B.; An, Z.; Zhang, X.; Barlow, S.; Li, Y.; Zhu, D.; Kippelen,
B.; Marder, S. R. J. Am. Chem. Soc. 2007, 129, 7246.
(23)Lin, Y.; Wang, Y.; Wang, J.; Hou, J.; Li, Y.; Zhu, D.; Zhan, X. Adv. Mater. 2014, 26, 5137.
(24)Sharenko, A.; Proctor, C. M.; van der Poll, T. S.; Henson, Z. B.; Nguyen, T.ꢀQ.; Bazan, G. C.
Adv. Mater. 2013, 25, 4403.
20
ACS Paragon Plus Environment

Page 21 of 25
Journal of the American Chemical Society
1
2
3
4
5
6
(25)Shivanna, R.; Shoaee, S.; Dimitrov, S.; Kandappa, S. K.; Rajaram, S.; Durrant, J. R.;
Narayan, K. S. Energy Environ. Sci. 2014, 7, 435.
7
8
9
(26)Guo, Y.; Li, Y.; Awartani, O.; Zhao, J.; Han, H.; Ade, H.; Zhao, D.; Yan, H. Adv. Mater. 2016,
28, 8483.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(27)Hartnett, P. E.; Timalsina, A.; Matte, H. S.; Zhou, N.; Guo, X.; Zhao, W.; Facchetti, A.;
Chang, R. P.; Hersam, M. C.; Wasielewski, M. R.; Marks, T. J. J. Am. Chem. Soc. 2014, 136, 16345.
(28)Gao, L.; Zhang, Z. G.; Xue, L.; Min, J.; Zhang, J.; Wei, Z.; Li, Y. Adv. Mater. 2016, 28,
1884.
(29)Earmme, T.; Hwang, Y.ꢀJ.; Murari, N. M.; Subramaniyan, S.; Jenekhe, S. A. J. Am. Chem.
Soc. 2013, 135, 14960.
(30)Li, H.; Hwang, Y.ꢀJ.; Courtright, B. A. E.; Eberle, F. N.; Subramaniyan, S.; Jenekhe, S. A.
Adv. Mater. 2015, 27, 3266.
(31)Li, H.; Kim, F. S.; Ren, G.; Hollenbeck, E. C.; Subramaniyan, S.; Jenekhe, S. A. Angew.
Chem. Int. Ed. 2013, 52, 5513.
(32)Zhou, E.; Cong, J.; Hashimoto, K.; Tajima, K. Adv. Mater. 2013, 25, 6991.
(33)Zhou, Y.; Kurosawa, T.; Ma, W.; Guo, Y.; Fang, L.; Vandewal, K.; Diao, Y.; Wang, C.; Yan,
Q.; Reinspach, J.; Mei, J.; Appleton, A. L.; Koleilat, G. I.; Gao, Y.; Mannsfeld, S. C. B.; Salleo, A.;
Ade, H.; Zhao, D.; Bao, Z. Adv. Mater. 2014, 26, 3767.
(34)Zhou, Y.; Ding, L.; Shi, K.; Dai, Y. Z.; Ai, N.; Wang, J.; Pei, J. Adv. Mater. 2012, 24, 957.
(35)Dou, C.; Long, X.; Ding, Z.; Xie, Z.; Liu, J.; Wang, L. Angew. Chem. Int. Ed. 2016, 55,
1436.
21
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 22 of 25
1
2
3
4
(36)Lin, Y.; Wang, J.; Zhang, Z.ꢀG.; Bai, H.; Li, Y.; Zhu, D.; Zhan, X. Adv. Mater. 2015, 27,
5
6
7
1170.
8
9
(37)Lin, Y.; Zhao, F.; He, Q.; Huo, L.; Wu, Y.; Parker, T. C.; Ma, W.; Sun, Y.; Wang, C.; Zhu, D.;
Heeger, A. J.; Marder, S. R.; Zhan, X. J. Am. Chem. Soc. 2016, 138, 4955.
(38)Lin, Y.; He, Q.; Zhao, F.; Huo, L.; Mai, J.; Lu, X.; Su, C. J.; Li, T.; Wang, J.; Zhu, J.; Sun, Y.;
Wang, C.; Zhan, X. J. Am. Chem. Soc. 2016, 138, 2973.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(39)Holliday, S.; Ashraf, R. S.; Wadsworth, A.; Baran, D.; Yousaf, S. A.; Nielsen, C. B.; Tan, C.
H.; Dimitrov, S. D.; Shang, Z.; Gasparini, N.; Alamoudi, M.; Laquai, F.; Brabec, C. J.; Salleo, A.;
Durrant, J. R.; McCulloch, I. Nat. Commun. 2016, 7, 11585.
(40)Liu, W.; Li, S.; Huang, J.; Yang, S.; Chen, J.; Zuo, L.; Shi, M.; Zhan, X.; Li, C.ꢀZ.; Chen, H.
Adv. Mater. 2016, 28, 9729.
(41)Bin, H.; Zhang, Z. G.; Gao, L.; Chen, S.; Zhong, L.; Xue, L.; Yang, C.; Li, Y. J. Am. Chem.
Soc. 2016, 138, 4657.
(42)Bin, H.; Gao, L.; Zhang, Z.ꢀG.; Yang, Y.; Zhang, Y.; Zhang, C.; Chen, S.; Xue, L.; Yang, C.;
Xiao, M.; Li, Y. Nat. Commun. 2016, 7, 13651.
(43)Yang, Y.; Zhang, Z. G.; Bin, H.; Chen, S.; Gao, L.; Xue, L.; Yang, C.; Li, Y. J. Am. Chem.
Soc. 2016, 138, 15011.
(44)Baran, D.; Ashraf, R. S.; Hanifi, D. A.; Abdelsamie, M.; Gasparini, N.; Rohr, J. A.; Holliday,
S.; Wadsworth, A.; Lockett, S.; Neophytou, M.; Emmott, C. J. M.; Nelson, J.; Brabec, C. J.;
Amassian, A.; Salleo, A.; Kirchartz, T.; Durrant, J. R.; McCulloch, I. Nat. Mater. 2016, DOI:
10.1038/nmat4797.
22
ACS Paragon Plus Environment

Page 23 of 25
Journal of the American Chemical Society
1
2
3
4
(45)Li, S.; Ye, L.; Zhao, W.; Zhang, S.; Mukherjee, S.; Ade, H.; Hou, J. Adv. Mater. 2016, 28,
5
6
7
8
9
9423.
(46)Yao, H.; Chen, Y.; Qin, Y.; Yu, R.; Cui, Y.; Yang, B.; Li, S.; Zhang, K.; Hou, J. Adv. Mater.
2016, 28, 8283.
(47)Li, Z.; Jiang, K.; Yang, G.; Lai, J. Y.; Ma, T.; Zhao, J.; Ma, W.; Yan, H. Nat. Commun. 2016,
7, 13094.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(48)Lin, Y.; Zhao, F.; Wu, Y.; Chen, K.; Xia, Y.; Li, G.; Prasad, S. K.; Zhu, J.; Huo, L.; Bin, H.;
Zhang, Z. G.; Guo, X.; Zhang, M.; Sun, Y.; Gao, F.; Wei, Z.; Ma, W.; Wang, C.; Hodgkiss, J.; Bo, Z.;
Inganas, O.; Li, Y.; Zhan, X. Adv. Mater. 2016, DOI: 10.1002/adma.201604155.
(49)Lin, Y.; Zhang, Z.ꢀG.; Bai, H.; Wang, J.; Yao, Y.; Li, Y.; Zhu, D.; Zhan, X. Energy Environ.
Sci. 2015, 8, 610.
(50)Wu, Y.; Bai, H.; Wang, Z.; Cheng, P.; Zhu, S.; Wang, Y.; Ma, W.; Zhan, X. Energy Environ.
Sci. 2015, 8, 3215.
(51)Cheng, P.; Zhang, M.; Lau, T.; Wu, Y.; Jia, B.; Wang, J.; Yan, C.; Qin, M.; Lu, X.; Zhan, X.
Adv. Mater. 2016, DOI: 10.1002/adma.201605216.
(52)Lei, T.; Xia, X.; Wang, J.ꢀY.; Liu, C.ꢀJ.; Pei, J. J. Am. Chem. Soc. 2014, 136, 2135.
(53)Sakamoto, Y.; Komatsu, S.; Suzuki, T. J. Am. Chem. Soc. 2001, 123, 4643.
(54)Kim, H. G.; Kang, B.; Ko, H.; Lee, J.; Shin, J.; Cho, K. Chem. Mater. 2015, 27, 829.
(55)Price, S. C.; Stuart, A. C.; Yang, L.; Zhou, H.; You, W. J. Am. Chem. Soc. 2011, 133, 4625.
(56) Li, W.; Albrecht, S.; Yang, L.; Roland, S.; Tumbleston, J. R.; McAfee, T.; Yan, L.; Kelly,
M. A.; Ade, H.; Neher, D.; You, W. J. Am. Chem. Soc. 2014, 136, 15566.
23
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 24 of 25
1
2
3
4
5
6
7
8
9
(57)Veldman, D.; Meskers, S. C. J.; Janssen, R. A. J. Adv. Funct. Mater. 2009, 19, 1939.
(58)Kawashima, K.; Fukuhara, T.; Suda, Y.; Suzuki, Y.; Koganezawa, T.; Yoshida, H.; Ohkita, H.;
Osaka, I.; Takimiya, K. J. Am. Chem. Soc. 2016, 138, 10265.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(59)Schilinsky, P.; Waldauf, C.; Brabec, C. J. Appl. Phys. Lett. 2002, 81, 3885.
(60)Lu, X.; Hlaing, H.; Germack, D. S.; Peet, J.; Jo, W. H.; Andrienko, D.; Kremer, K.; Ocko, B.
M. Nat. Commun. 2012, 3, 795.
(61)Mai, J.; Lau, T.ꢀK.; Li, J.; Peng, S.ꢀH.; Hsu, C.ꢀS.; Jeng, U. S.; Zeng, J.; Zhao, N.; Xiao, X.;
Lu, X. Chem. Mater. 2016, 28, 6186.
(62)Shin, W. S.; Jeong, H.ꢀH.; Kim, M.ꢀK.; Jin, S.ꢀH.; Kim, M.ꢀR.; Lee, J.ꢀK.; Lee, J. W.; Gal,
Y.ꢀS. J. Mater. Chem. 2006, 16, 384.
24
ACS Paragon Plus Environment

Page 25 of 25
Journal of the American Chemical Society
1
2
3
4
5
For Table of Contents use only
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
25
ACS Paragon Plus Environment