Methane-perylene diimide-based small molecule acceptors for high efficiency non-fullerene organic solar cells

Article abstract of DOI:10.1039/c9tc03457a

We report perylene diimide (PDI) small molecules based on diphenylmethane, triphenylmethane, and tetraphenylmethane cores, named PM-PDI₂, PM-PDI₃ and PM-PDI₄, respectively. The OSC performances of PM-PDI₃ and PM-PDI₄ are comparable. The PM-PDI₃ based device with PDBT-T1 as the donor achieved a highest power conversion efficiency (PCE) of 7.58% along with a high open-circuit voltage (V_OC) of 0.98 V, a short-circuit current density (J_SC) of 11.02 mA cm^-2 and a high fill factor (FF) of 69.9%, a 1.32 times boost in PCE with respect to the PM-PDI₂ based control device (3.26%). The high photovoltaic performance of the PM-PDI₃ based device can be attributed to its relatively high-lying LUMO level, complementary absorption spectra with the polymer donor material PDBT-T1, relatively favorable morphology and improved exciton dissociation and charge collection efficiency. A PCE of 7.58% is among the highest efficiency of phenyl-methane as core based non-fullerene organic solar cells. Overall, this work provides a new approach to enhance the performance of non-fullerene acceptors.

Full text of DOI:10.1039/c9tc03457a

View Article Online
View Journal
Journal of
Materials Chemistry C
Materials for optical, magnetic and electronic devices
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: G. Li, W. Yang, S.
Wang, T. Liu, C. Yan, G. Li, Y. Zhang, D. Li, X. Wang, P. Hao, J. Li, L. Huo, H. Yan and B. Tang, J. Mater.
Chem. C, 2019, DOI: 10.1039/C9TC03457A.
Volume
Number
6
5
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
7
February 2018
Pages 911-1266
Journal of
Materials Chemistry C
Materials for optical, magnetic and electronic devices
rsc.li/materials-c
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 2050-7526
PAPER
Nosang V. Myung, Yong-Ho Choa et al.
A
noble gas sensor platform: linear dense assemblies of
a multi-layered
single-walled carbon nanotubes (LACNTs) in
ceramic/metal electrode system (MLES)
rsc.li/materials-c

Page 1 of 8
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C9TC03457A
TOC
High efficiencies of 7.58% is obtained in non-fullerene OSCs using PM-PDI3 as the
acceptors and PDBT-T1 as the donor.

Please do not adjust margins
Journal of Materials Chemistry C
Page 2 of 8
View Article Online
DOI: 10.1039/C9TC03457A
ARTICLE
Methane-Perylene Diimides-Based Small Molecule Acceptors for
High Efficiency Non-Fullerene Organic Solar Cells
Received 00th January 20xx,
Accepted 00th January 20xx
Gang Li,*a‡ Wenbin Yang,a‡ Shuaihua Wang,a‡ Tao Liu,*ab‡ Cenqi Yan,c Gang Li,c Yu Zhang,a Dandan
Li,a Xinyu Wang,a Pin Hao, a Jiewei Li,d Lijun Huo,*e He Yan*b and Bo Tang *a
DOI: 10.1039/x0xx00000x
We reported perylene diimide (PDI) small molecules based on diphenylmethane, triphenylmethane, and
tetraphenylmethane cores, named as PM-PDI2, PM-PDI3 and PM-PDI4, respectively. The OSCs performances of PM-PDI3
and PM-PDI4 are comparable. The PM-PDI3 based device with PDBT-T1 as the donor achieved a highest power conversion
efficiency (PCE) of 7.58% along with a high open-circuit voltage (VOC) of 0.98 V, a short-circuit current density (JSC) of 11.02
mA cm-2 and a high fill factor (FF) of 69.9%, a 1.32 times boost in PCE with respect to the PM-PDI2 based control device
(3.26%). The high photovoltaic performance of the PM-PDI3 based device can be attributed to its relatively high-lying
LUMO level, complementary absorption spectra with the polymer donor material PDBT-T1, relatively favorable
morphology and improved exciton dissociation and charge collection efficiency. A PCE of 7.58% is among the highest
efficiency of phenyl-methane as core based non-fullerene organic solar cells. Overall, this work provides a new approach
to enhance the performance of non-fullerene acceptors.
especially for the systems of ITIC 18, 20-30and perylene diimides
(PDIs).31, 32 Recently, Zou group reported single-junction OSCs
devices based on Y6 exceeded a power conversion efficiency
(PCE) of 16%;33 Chen group reported the highest PCE of 17.3%
in tandem devices based on PBDB-T:F-M and PTB7-Th:O6T-
4F:PC71BM,34 demonstrating the great potential of non-
fullerene acceptors for future commercialization.
Perylene diimide (PDI) small molecule is competitive among
the various non-fullerene acceptors. They have several
advantages: (1) easy to large-scale preparation and
purification;35 (2) adjustability of molecular structure, energy
levels, and absorption range (PDI moiety provide several
substitution sites, including the bay position,36, 37 the non-bay
position 38and the nitrogen atoms.);39 (3) high electron
mobilities in the order of 101–10-3 cm2 V-1s-1.40
Introduction
In the past decade, organic solar cells (OSCs) consisting of
donors and acceptors as active layers, have attracted
increasing attention owing to their advantages of light weight,
low cost, solution-processing ability and their potential
application in flexible devices.1-11 Fullerene derivatives, have
been dominant electron acceptors in OSCs for the past few
decades, and their success is attributed to their outstanding
electron- withdrawing ability and charge transport
properties.12-14 However, they suffer from some intrinsic
drawbacks, such as poor spectral absorption, limited tunablity
of chemical structures and energy level, high-cost purification
and morphological instability, hindering the further
commercialization of fullerene OSCs.15 Therefore, research on
non-fullerene acceptors (NFA) is of significance.
Despite the above-mentioned advantages of PDIs derivatives,
PDIs tend to form large aggregates domains due to their large
and planar structures, which may aggravate geminate
recombination and deteriorate device performance.
Accordingly, we need to make efforts to suppress the
formation of 1D π stacking while trying to retain sufficient
intermolecular LUMO-LUMO overlap for adequate electron
transport. This can be achieved by constraining two or more
PDIs to be non-planar and/or with the introduction of a
conjugated bridge.41, 42 Previously, Yan group reported that a
PDI dimer featuring spirobifluorene linker, named as SF-PDI2,
NFA materials, possessing the favorable electron-accepting
and transporting properties, are believed to excel fullerene
and have undergone rapid development. A variety of high
performance fullerene-free acceptors have been invented,16-19
a. College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory
of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation
Center of Functionalized Probes for Chemical Imaging in Universities of Shandong,
Institute of Materials and Clean Energy, Shandong Provincial Key Laboratory of
Clean Production of Fine Chemicals, Shandong Normal University, Jinan 250014,
P. R. China. E-mail: ligang@sdnu.edu.cn; tangb@sdnu.edu.cn
b. Department of Chemistry and Energy Institute, The Hong Kong University of
Science and Technology, Clear Water Bay, Hong Kong, E-mail: Liutaozhx@ust.hk;
hyan@ust.hk
which achieved an impressive PCE of 9.50% with a high VOC of
31
1.11 V with the low bandgap polymer P3TEA.
developed
Our group
a
star-shaped PDI trimer TPA-PDI3 with a
c. Department of Electronic and Information Engineering, The Hong Kong
Polytechnic University, Hong Hum, Kowloon, Hong Kong, China.
d. Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials
(IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials
(SICAM); Nanjing Tech University (NanjingTech), 30 South Puzhu Road, Nanjing,
211816, P.R. China.
triphenylamine (TPA) core, which displayed weak molecular
aggregation, strong absorption as well as energy levels
matched with the donor of PBDB-T, OSCs based on PBDB-T:
TPA-PDI3 gave a PCE of 5.84 %.36b Yan group used the ring-
fusion strategy to obtain a novel PDI tetramer named FTTB-
PDI4, and achieved a PCE of 10.58% by matching FTTB-PDI4
with the polymeric donor P3TEA, which is the highest value for
PDI small molecule-based OSCs.32
e. School of Chemistry, Beihang University, Beijing 100191, P. R. China, E-mail:
huolijun@buaa.edu.cn
‡These authors contributed equally to the work.
Electronic Supplementary Information (ESI) available: [Details of synthesis and
characterization]. See DOI: 10.1039/x0xx00000x
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry C
Page 3 of 8
ARTICLE
Journal Name
View Article Online
DOI: 10.1039/C9TC03457A
Fig. 1 Absorption spectra of PBDB-T1, PM-PDI2, PM-PDI3 and PM-PDI4 films.
and PM-PDI4 were obtained by reacting the borate ester and
monobromo-PDI through Suzuki coupling reaction in the
presence of Pd(PPh3)4. The purification of PM-PDI2 was easy
due to relatively less by-products, but the purification of PM-
PDI3 and PM-PDI4 were very different due to multiple reaction
sites, and we purified them by repeated column
chromatograph. All of the new compounds have been fully
1
characterized by H NMR, 13C NMR and FT-IR. Although the
satisfactory mass spectra of PM-PDI2 and PM-PDI4 were not
available owing to the influence of matrix, ion detection mode
and concentration of samples, the molecular ion peaks
(MALDI-TOF-MS) of these three compounds have been
successfully acquired (Fig. S15-S17). All of the new compounds
Scheme 1. The synthesis routes of PM-PDI2, PM-PDI3 and PM-PDI4.
Despite the progress mentioned above, more efforts should
be made to improve photovoltaic performances towards
commercialization. Therefore, it is of importance to design and
synthesize new acceptor materials, and investigate the
relationship between molecular structure and OSCs
performance.43
1
have been fully characterized by H NMR, 13C NMR, FT-IR and
high-resolution mass spectra (HRMS). The three target
products are highly soluble in general organic solvents, such as
dichloromethane,
tetrahedronfunan
(THF),
ortho-
Bearing these considerations in mind, we designed and
synthesized phenyl-methane based PDI dimer, PDI trimer and
tetramers, named PM-PDI2, PM-PDI3 and PM-PDI4,
respectively. Their structures are shown in Scheme 1. Their
photophysicial and electrochemical properties, molecular
simulations, charge transport and photovoltaic properties
were investigated in detail. All these acceptor molecules have
a central phenyl-substituted methane core and the peripheral
PDI units are directly linked to the benzene. PM-PDI2 is a V-
type molecule, which contains two flanked PDI units; PM-PDI3
is a star-shape C3-symmetrical molecule with three peripheral
PDI units; and PM-PDI4 is a C4-symmetrical molecule with four
PDI units linked to the central benzene. The influences of the
varied molecular geometries on the photophysical properties,
the active layers morphologies and the photovoltaic
performances are studied in detail.
dichlorobenzene (o-DCB), and chloroform at room
temperature. Such good solubility is mainly ascribed to the
tridimensional molecular scaffold. The thermal properties
were evaluated by thermal gravimetric analysis (TGA)
performed under nitrogen atmosphere. The three target
products have the decomposition temperature (5% weight loss)
of above 300 °C (Fig. S18).
Optical and electrochemical properties
Results and discussion
Material synthesis and characterization
The synthesis routes to all three compounds are shown in
Scheme 1. The precursor of borate ester (1-3) was synthesized
according to boylation coupling reaction of corresponding
bromide
with bis(pinacolato)diboron catalyzed with
Pd(dppf)Cl2. Another precursor of monobromo-PDI (4) was
obtained via bromination of PDIs according to the known
procedures.44 Then the final products of PM-PDI2, PM-PDI3
Fig. 2 CV curves of PM-PDI2, PM-PDI3, PM-PDI4 and mono PDI (shown in Fig. S1)
.
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Journal of Materials Chemistry C
Please do not adjust margins
Page 4 of 8
Journal Name
ARTICLE
The absorption spectra of PM-PDI2, PM-PDI3 and PM-PDI4 Moreover, the distinct dihedral angles (Fig.S6) between
View Article Online
DOI: 10.1039/C9TC03457A
are shown in Fig. 1 and Figs S2-3 and corresponding data are adjacent PDIs indicate that the flanking PDIs in phenyl-
provided in Table 1. The three PDI acceptors demonstrated methane core form the large steric repulsion, especially for
similar absorption spectra in solution. PM-PDI2 in PM-PDI3 and PM-PDI4, suggesting that the more introduction
dichloromethane solution showed a broad absorption in the of PDIs units, results in
a more twisted molecular
range of 450-600 nm with a maximum at 534 nm. PM-PDI3 and configuration. Furthermore, the theoretically predicted HOMO
PM-PDI4 demonstrated almost same absorption spectra with and LUMO energy levels and bandgap of three compounds fit
PM-PDI2, but the molar extinction coefficient ε values of PM- quite well with the values obtained by CV experiment (Table 2
PDI2, PM-PDI3 and PM-PDI4 solutions ascend from 1.44 × 105 and S1).
to 1.90 × 105 to 2.09 × 105 M-1 cm-1 with increasing number of
PDI units. From the solution to the film, the absorption edges Photovoltaic Properties
red-shift by ca. 50 nm, suggesting the intermolecular π -π
We used polymeric donor (PDBT-T1) and PDI acceptors (PM-
PDI2, PM-PDI3 and PM-PDI4) to construct OSCs with a
conventional device configuration: ITO glass/ PEDOT:PSS /
active layers / Zracac /Al. Where ITO is indium tin oxide,
PEDOT is poly(3,4-ethylenedioxythiophene) and PSS is
poly(styrenesulfonate). The p-type polymer PDBT-T1 was
selected as the donor material because of complementary
absorption and the matched energy levels with these three
stacking of these acceptors in the solid state. PM-PDI2, PM-
PDI3 and PM-PDI4 pure films exhibit optical absorption onsets
of 598 nm, 596 nm and 596 nm, respectively. As illustrated in
Fig. 1, the main absorption of PDBT-T1 is in the range from 400
to 700 nm, which complements the absorption spectrum of
opt
PM-PDI2, PM-PDI3 and PM-PDI4. The optimal band gaps (Eg
)
Fig. 3 Molecular energy level diagrams of electron donors and acceptors. (LUMO
levels were calculated from the HOMO levels and optical bandgap.)
of three PDIs derivatives estimated from the film absorption
edges are 2.07, 2.08 and 2.08 eV, respectively.
The electrochemical properties of PM-PDI2, PM-PDI3 and PM-
PDI4 in dichloromethane solutions were investigated by cyclic
voltammetry (CV) as shown in Fig. 2. The LUMO energy levels
of these molecules were calculated from the onset reduction
potentials according to the equation of ELUMO = -e (Ered + 4.80)
(eV), assuming the Fc/Fc+ to be −4.8 eV.32 The HOMO energy
opt
levels were estimated from the equation EHOMO = ELUMO–Eg
(eV). The corresponding energy levels data were summarized
in Table 1. The LUMO levels up-shift from −3.90 to −3.86 eV,
with the increased number of PDI units. The high-lying LUMO
of PM-PDI4 potentially contributes to the high open-circuit
voltage. It is worth noting that PM-PDI2 exhibits lower LUMO
energy levels than PM-PDI3 and PM-PDI4, which should be
attributed to the relatively lower dipole moment of symmetric
structure.
Fig. 4 (a) J–V curves of PDBT-T1:PM-PDI2, PDBT-T1:PM-PDI3 and PDBT-T1:PM-
PDI4-based devices. (b) IPCE curves of the devices.
Theoretical analysis
To gain deep insight into the structural and electronic
properties of PM-PDI2, PM-PDI3 and PM-PDI4, density function
theory (DFT) calculation4545 (B3LYP/6-31G*)45 was performed
on the three molecules. The optimized configurations and
orbital distributions of HOMO and LUMO energy levels are
illuminated in Fig. S6. The electron clouds of HOMO energy
levels were delocalized throughout the PDI core, while the
LUMO energy levels are dominated by perylene diimides core.
acceptors (See Fig. 3 and Fig. S1). The processing solvent for
the active layer is chlorobenzene (DCB) with
a total
concentration of 20 mg/mL. The detailed device fabrications
and measurements are demonstrated in Supporting
Information. The optimal conditions for preparing the devices
were obtained by changing film thickness, annealing
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry C
Page 5 of 8
ARTICLE
Journal Name
temperatures and additives carefully. The optimized weight
ratio of D / A was 1:1 and the optimized film thickness is ca. 95
nm. The optimized ratio of 1,8-Diiodooctane (DIO) was 0.25%.
Figure 4a illustrates the current density-voltage (J-V) curves of
OSCs based on PDBT-T1:PM-PDI2, PDBT-T1:PM-PDI3, and
PDBT-T1:PM-PDI4, and the detailed photovoltaic parameters
are shown in Table 2. The PDBT-T1:PM-PDI4-based device
yields a PCE of 7.52%, with an open-circuit voltage (VOC) of
1.01 V, a JSC of 11.20 mA cm−2 and a fill factor (FF) of 0.67. In
contrast, the PDBT-T1:PM-PDI2-based device exhibits a low
PCE of 3.26%, with an enhanced VOC (0.98 V) but reduced JSC
(8.49 mA cm−2) and FF (39.3%). PDBT-T1:PM-PDI3 showed an
impressive PCE as high as 7.58%, with a VOC of 0.98 V, a JSC of
11.02 mA cm−2 and a FF of 69.9% under the illumination of AM
1.5G, 100 mW cm−2. Benefiting from the increased JSC and FF in
PDBT-T1:PM-PDI3 and PDBT-T1:PM-PDI4-based OSCs, both
devices exhibit higher PCEs than the PDBT-T1:PM-PDI2
counterpart.
View Article Online
DOI: 10.1039/C9TC03457A
To clarify the charge mobilities in the OSCs devices, we have
measured electron and hole mobilities in the blend films by
the space charge limited current (SCLC) method. Hole-only
diodes with the structure of ITO/MoOX/active layers/MoOX/Al
and electron-only diodes with the structure of ITO/ZnO/active
layer/Zracac/Al were fabricated and measured to extract the
hole (μh) and electron (μe) mobilities of PM-PDIx pure films,
and PDBT-T1:PM-PDIx blend films (Fig. 5, S4 and Table S2.) The
μes values of PM-PDI2, PM-PDI3 and PM-PDI4 pristine films
changed from 5.78 × 10−4 to 7.08 × 10−4 to 7.39 × 10−4
cm2V−1s−1 with increasing number of PDI units. PM-PDIx pure
films, and PDBT-T1:PM-PDIx blend films have μes in the same
magnitude, which implied that efficient electron-transport
pathways are unaffected to a great extent by the presence of
the donor polymer. The μh /μe of three blend films were 2.19,
1.70 and 1.75, respectively. PM-PDI3 and PM-PDI4 -based blend
films showed increased hole and electron mobility and more
balanced μh and μe, which benefits to the charge transport and
corresponds with high fill factor.46
The incident photon-to-current conversion efficiency (IPCE)
spectra of the optimal devices based on PM-PDI2, PM-PDI3 and
PM-PDI4 are displayed in Fig. 4b. JSCs integrated from IPCE
Morphology characterization
The surface morphology measurements of BHJ active layer were
performed using atomic force microscopy (AFM). As can be seen
from AFM height images (Fig. 6), PDBT-T1:PM-PDI2 blend film
displayed a smooth and uniform morphologies with slightly larger
root mean square (RMS) surface roughness of 1.81 nm than PDBT-
T1:PM-PDI3 and PDBT-T1:PM-PDI4, which could be attributed to
the stronger PDI aggregation therein. In contrast, PDBT-T1:PM-
PDI3 and PDBT-T1:PM-PDI4 demonstrated relatively clear and
delicate nanofibrillar structures; and no strong molecule
aggregation between PDBT-T1 and the two acceptors occurred,
which are beneficial for charge transport and extraction.
Exciton dissociation and charge extraction
Charge collection and exciton dissociation in active layers
were also investigated and the corresponding curves of
photocurrent density versus effective voltage of the optimal
OSCs are shown in Fig. 7a. The saturation photocurrent density
(Jsat), exciton dissociation efficiency (ηdiss) and charge collection
efficiency (ηcoll) can be estimated from the curves of Jph and Veff.
The exciton dissociation efficiency (ηdiss = JSC/Jsat) and charge
collection efficiency (ηcoll = Jmax/Jsat) were calculated under the
short circuit and maximum power output conditions, are
74.6%, 92.8% and 90.8%, respectively, and corresponding ηcoll
are 39.4%, 77.6% and 74.2%. The much higher ηdiss and ηcoll
values of PM-PDI3 and PM-PDI4 -based device demonstrates its
higher exciton dissociation and charge collection efficiency,
corresponding with their higher JSC and FF. 47
Fig. 5 Dark current density-voltage characteristics for a) hole-only and b) electron-only
devices with optimized PDBT-T1: PM-PDI2, PDBT-T1: PM-PDI3 and PDBT-T1: PM-PDI4
BHJ films.
Charge-recombination
match well with the values from the J-V curves within 4% error
(Table 2). We can see that the IPCE curves for all the three
types of devices cover a broad and strong photoresponse
range from 300 to 700 nm. The IPCE values of PM-PDI3 and
PM-PDI4-based solar cells are distinctly higher than the
counterpart of PM-PDI2.
We investigated charge recombination by measuring Jsc at
different light intensities (P), as shown in Fig. 7b, and the
corresponding data were summarized in Table S3. The
relationship between Jsc and P can be describe using Jsc ∝ PS,
when S = 1 indicates that all the free carriers are collected and
swept out before recombination, when S < 1, indicates a
Active Layer Charge Transport
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Journal of Materials Chemistry C
Please do not adjust margins
Page 6 of 8
Journal Name
ARTICLE
certain degree of bimolecular recombination.48 The bimolecular recombination49 of PDBT-T1:PM-PDI3 and PDBT-
View Article Online
recombination parameters S are 0.872, 0.971 and 0.940 for the T1:PM-PDI4 -based devices, which are consistent with their
DOI: 10.1039/C9TC03457A
devices with PDBT-T1:PM-PDI2, PDBT-T1:PM-PDI3 and PDBT- higher JSC and FF.
T1:PM-PDI4 BHJ films, respectively, suggesting weak
Fig. 6 Film morphology images, AFM height (A-C) and phase (D-F) images of blend films. A, D) PDBT-T1: PM-PDI2, RMS = 1.81 nm; B, E) PDBT-T1: PM-PDI3, RMS = 1.23
nm; C, F) PDBT-T1: PM-PDI4, RMS = 1.17 nm.
Table 1. Basic Properties of PDBT-T1: PM-PDI2, PDBT-T1: PM-PDI3 and PDBT-T1: PM-PDI4
.
LUMOd)
(eV)
μe
a)
a)
a)
b)
b)
e)
λmax
εmax
λonset
λmax
λonset
Egopt c)
(eV)
HOMO
(eV)
Acceptors
(nm)
(M-1 cm-1)
(nm)
(nm)
(nm)
(cm2 V-1 s-1)
PM-PDI2
PM-PDI3
533
1.44 × 105
576
540
598
2.07
2.08
−5.97
−5.97
-3.90
-3.89
5.78 × 10-4
534
535
1.90 × 105
576
510
541
596
596
7.08 × 10-4
7.39 × 10-4
PM-PDI4
2.09 × 105
576
2.08
−5.94
-3.86
a)
b)
c)
opt
d)
In a dichloromethane solution. In a neat film. Calculated from empirical the formula: Eg = 1240/λonset
.
Cyclic voltammetry (CV) method by
measuring in dichloromethane. e) Measured by the space charge limited current (SCLC) method.
Table 2. Performance of the optimized OSCs devices based on PDBT-T1: PM-PDI2, PDBT-T1: PM-PDI3 and PDBT-T1: PM-PDI4 (1:1, w/w).
FF a)
(%)
0.393
PCE a)
(%)
3.26
a)
a)
b)
VOC
JSC
JSC
Active layer
Additive
(V)
0.978
(mA cm-2)
8.490
(mA cm-2)
PDBT-T1:PM-PDI2
0.25% DIO
(
(
0.972±0.010
)
(
8.218±0.221
)
8.211
(
(
0.392±0.006
)
(3.131±0.192)
0.984
11.022
0.699
7.58
(7.331±0.205)
PDBT-T1:PM-PDI3
PDBT-T1:PM-PDI4
0.25% DIO
0.25% DIO
0.987±0.009
)
(
10.765±0.241
)
10.668
10.946
0.690±0.011
)
1.007
11.203
0.667
7.52
(7.137±0.212)
(0.993±0.011)
(10.875±0.238)
(0.661±0.005)
a)
Values are for the highest-PCE device, with average values obtained from 20 devices listed in parentheses. b) JSC value from the integration
of the EQE spectra are within 4% error of those from J-V curves.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry C
Page 7 of 8
View Article Online
DOI: 10.1039/C9TC03457A
ARTICLE
prospects for OSC applications. Furthermore, PDBT-T1:PM-
PDI3 and PDBT-T1:PM-PDI4 active layers delivered a high PCE
of 7.58% and 7.52%, outcompeting PDBT-T1:PM-PDI2. Notably,
compared with PM-PDI4, the slightly enhanced PCE of PM-PDI3
mainly attributed to improved FF of 69.9%, which is one of the
highest FF for the PDI-based OSCs to date. Our results
demonstrated that PDIs’ number in PDI small molecules had a
significant impact on the photovoltaic performance.
Conflicts of interest
There are no conflicts to declare.
Acknowledgements
B. Tang acknowledges the National Natural Science Foundation
of China (No. 21535004, 21390411, 91753111). G. Li
acknowledges the financial support from Shandong Province
Natural Science Foundation (ZR2016BM24) and start-up grant
of Shandong Normal University.
Notes and references
Fig. 7 (a) Light intensity dependence of JSC of the devices. (b) Jph versus Veff of the
optimized devices
1
2
3
4
5
L. Lu, M. A. Kelly, W. You and L. Yu, Nat. Photon., 2015, 9,
491.
G. Li, W.-H. Chang and Y. Yang, Nat. Rev. Mater., 2017, 2,
17043.
A. Polman, M. Knight, E. C. Garnett, B. Ehrler and W. C.
Sinke, Science, 2016, 352, 6283.
R. Ganesamoorthy, G. Sathiyan and P. Sakthivel, Sol. Energ.
Mat. Sol. C., 2017, 161, 102.
P. Cheng, G. Li, X. Zhan and Y. Yang, Nat. Photon., 2018, 12,
131.
Y. Lin and X. Zhan, Acc. Chem. Res., 2016, 49, 175.
J. Hou, O. Inganäs, R. H. Friend and F. Gao, Nat. Mater.,
2018, 17, 119.
C. Yan, S. Barlow, Z. Wang, H. Yan, A. K. Y. Jen, S. R. Marder
and X. Zhan, Nat. Rev. Mater., 2018, 3, 18003.
G. Zhang, J. Zhao, P. C. Y. Chow, K. Jiang, J. Zhang, Z. Zhu, J.
Zhang, F. Huang and H. Yan, Chem. Rev., 2018, 118, 3447.
In addition to the OSCs performance, the acceptor’s cost still
deserves the attention of materials scientists. Facile synthesis
and the high yields for such PDI-based acceptors enable ready
materials access at greatly reduced cost. Taking PM-PDI3 for
example, the synthetic cost of PDI material was estimated to
be 620 RMB /g (≈ 90 $/g) based on the price of solvents and
chemicals supplied in China (Table S4), which is far less than
the price of fused-ring electron acceptors represented by ITIC.
Furthermore, if large-scale preparation is performed, the cost
is expected to further reduced, showing the distinctive
advantage of PDIs materials for industrial applications.
6
7
8
9
10 F. Shen, J. Xu, X. Li and C. Zhan, J. Mater. Chem. A., 2018, 6,
15433.
11 C. Li, H. Fu, T. Xia and Y. Sun, Adv. Energy. Mater., 2019,
1900999. doi: 10.1002/aenm.201900999.
12 M. Li, K. Gao, X. Wan, Q. Zhang, B. Kan, R. Xia, F. Liu, X. Yang,
H. Feng, W. Ni, Y. Wang, J. Peng, H. Zhang, Z. Liang, H.-L. Yip,
X. Peng, Y. Cao and Y. Chen, Nat. Photon., 2016, 11, 85.
13 J. Zhao, Y. Li, G. Yang, K. Jiang, H. Lin, H. Ade, W. Ma and H.
Yan, Nat. Energy., 2016, 1, 15027.
14 D. Deng, Y. Zhang, J. Zhang, Z. Wang, L. Zhu, J. Fang, B. Xia, Z.
Wang, K. Lu, W. Ma and Z. Wei, Nat. Commun., 2016, 7,
13740.
Conclusions
In conclusion, we designed and synthesized three methane-
perylene diimides-based small molecular acceptors, PM-PDI2,
PM-PDI3 and PM-PDI4, and investigated the effects of PDIs’
number on photophysical, electronic, charge-transport,
photovoltaic, and morphological properties. PM-PDI3 and PM-
PDI4 exhibit relatively stronger absorption profile, upshifted
LUMO energy level and a higher electron mobility than PM-
PDI2, which endow PM-PDI3 and PM-PDI4 with better
Please do not adjust margins

Journal of Materials Chemistry C
Please do not adjust margins
Page 8 of 8
Journal Name
ARTICLE
15 B. Kan, H. Feng, X. Wan, F. Liu, X. Ke, Y. Wang, Y. Wang, H. 38 H. Wang, L. Chen and Y. Xiao, J. Mater. Chem. C., 2019, 7,
View Article Online
Zhang, C. Li, J. Hou and Y. Chen, J. Am. Chem. Soc., 2017, 139,
4929.
835.
39 H. Fu, D. Meng, X. Meng, X. Sun, L. HuDoO, IY:.10F.a1n03,9Y/.CL9iT,CW03.4M57aA,
Y. Sun and Z. Wang, J. Mater. Chem. A., 2017, 5, 3475.
16 Z. Luo, H. Bin, T. Liu, Z. G. Zhang, Y. Yang, C. Zhong, B. Qiu, G.
Li, W. Gao, D. Xie, K. Wu, Y. Sun, F. Liu, Y. Li and C. Yang, Adv. 40 X. Zhang, Z. Lu, L. Ye, C. Zhan, J. Hou, S. Zhang, B. Jiang, Y.
Mater., 2018, 30, 1706124.
Zhao, J. Huang, S. Zhang, Y. Liu, Q. Shi, Y. Liu and J. Yao, Adv.
Mater., 2013, 25, 5791.
41 D. Sun, D. Meng, Y. Cai, B. Fan, Y. Li, W. Jiang, L. Huo, Y. Sun
and Z. Wang, J. Am. Chem. Soc., 2015, 137, 11156.
42 D. Meng, D. Sun, C. Zhong, T. Liu, B. Fan, L. Huo, Y. Li, W.
Jiang, H. Choi, T. Kim, J. Y. Kim, Y. Sun, Z. Wang and A. J.
Heeger, J. Am. Chem. Soc., 2016, 138, 375.
43 A. Wadsworth, M. Moser, A. Marks, M. S. Little, N. Gasparini,
C. J. Brabec, D. Baran and I. McCulloch, Chem. Soc. Rev.,
2019, 48, 1596.
17 Q. An, W. Gao, F. Zhang, J. Wang, M. Zhang, K. Wu, X. Ma, Z.
Hu, C. Jiao and C. Yang, J. Mater. Chem. A, 2018, 6, 2468.
18 W. Zhao, S. Li, H. Yao, S. Zhang, Y. Zhang, B. Yang and J. Hou,
J. Am. Chem. Soc., 2017, 139, 7148.
19 T. J. Aldrich, M. Matta, W. Zhu, S. M. Swick, C. L. Stern, G. C.
Schatz, A. Facchetti, F. S. Melkonyan and T. J. Marks, J. Am.
Chem. Soc., 2019, 141, 3274.
20 Y. Lin, J. Wang, Z.-G. Zhang, H. Bai, Y. Li, D. Zhu and X. Zhan,
Adv. Mater., 2015, 27, 1170.
21 Q. An, X. Ma, J. Gao, F. Zhang, Sci. Bull. 2019, 64, 504.
44 Q. Yan and D. Zhao, Org. Lett., 2009, 11, 3426.
22 H. Yao, Y. Cui, R. Yu, B. Gao, H. Zhang and J. Hou, Angew. 45 R. D. F. Gaussian 09, M. J. et al. Gaussian, Inc.,Wallingford,
Chem. Int. Ed., 2017, 56, 3045.
CT, 2009, see supporting information for full citation.
23 N. D. Eastham, J. L. Logsdon, E. F. Manley, T. J. Aldrich, M. J. 46 Q. An, J. Wang, F. Zhang, Nano Energy, 2019, 60, 768.
Leonardi, G. Wang, N. E. Powers-Riggs, R. M. Young, L. X. 47 X. Ma, M. Luo, W. Gao, J. Yuan, Q. An, M. Zhang, Z. Hu, J.
Chen, M. R. Wasielewski, F. S. Melkonyan, R. P. H. Chang and
T. J. Marks, Adv. Mater., 2018, 30, 1704263.
Gao, J. Wang, Y. Zou, C. Yang and F. Zhang, J. Mater. Chem.
A, 2019, 7, 7843.
24 X. Yi, B. Gautam, I. Constantinou, Y. Cheng, Z. Peng, E. Klump, 48 T. Liu, L. Huo, S. Chandrabose, K. Chen, G. Han, F. Qi, X.
X. Ba, C. H. Y. Ho, C. Dong, S. R. Marder, J. R. Reynolds, S.-W.
Tsang, H. Ade and F. So, Adv. Func. Mater., 2018, 28,
1802702.
Meng, D. Xie, W. Ma, Y. Yi, J. M. Hodgkiss, F. Liu, J. Wang, C.
Yang and Y. Sun, Adv. Mater., 2018, 30, 1707353.
49 Z. Hu, F. Zhang, Q. An, M. Zhang, X. Ma, J. Wang, J. Zhang, J.
Wang, ACS Energy Lett., 2018, 3, 555.
25 Z. Fei, F. D. Eisner, X. Jiao, M. Azzouzi, J. A. Röhr, Y. Han, M.
Shahid, A. S. R. Chesman, C. D. Easton, C. R. McNeill, T. D.
Anthopoulos, J. Nelson and M. Heeney, Adv. Mater., 2018,
30, 1705209.
26 Z. Yao, X. Liao, K. Gao, F. Lin, X. Xu, X. Shi, L. Zuo, F. Liu, Y.
Chen and A. K. Y. Jen, J. Am. Chem. Soc., 2018, 140, 2054.
27 Z. Zheng, Q. Hu, S. Zhang, D. Zhang, J. Wang, S. Xie, R. Wang,
Y. Qin, W. Li, L. Hong, N. Liang, F. Liu, Y. Zhang, Z. Wei, Z.
Tang, T. P. Russell, J. Hou and H. Zhou, Adv. Mater., 2018, 30,
1801801.
28 W. Li, L. Ye, S. Li, H. Yao, H. Ade and J. Hou, Adv. Mater.,
2018, 30, 1707170.
29 R. Yu, H. Yao, L. Hong, Y. Qin, J. Zhu, Y. Cui, S. Li and J. Hou,
Nat. Commun., 2018, 9, 4645.
30 B. Fan, X. Du, F. Liu, W. Zhong, L. Ying, R. Xie, X. Tang, K. An,
J. Xin, N. Li, W. Ma, C. J. Brabec, F. Huang and Y. Cao, Nat.
Energy., 2018, 3, 1051.
31 J. Liu, S. Chen, D. Qian, B. Gautam, G. Yang, J. Zhao, J.
Bergqvist, F. Zhang, W. Ma, H. Ade, O. Inganäs, K. Gundogdu,
F. Gao and H. Yan, Nat. Energy., 2016, 1, 16089.
32 J. Zhang, Y. Li, J. Huang, H. Hu, G. Zhang, T. Ma, P. C. Y. Chow,
H. Ade, D. Pan and H. Yan, J. Am. Chem. Soc., 2017, 139,
16092.
33 J. Yuan, Y. Zhang, L. Zhou, G. Zhang, H.-L. Yip, T.-K. Lau, X. Lu,
C. Zhu, H. Peng, P. A. Johnson, M. Leclerc, Y. Cao, J. Ulanski,
Y. Li and Y. Zou, Joule, 2019, 3, 1140.
34 L. Meng, Y. Zhang, X. Wan, C. Li, X. Zhang, Y. Wang, X. Ke, Z.
Xiao, L. Ding, R. Xia, H.-L. Yip, Y. Cao and Y. Chen, Science,
2018, 361, 1094.
35 A. Nowak-Król, K. Shoyama, M. Stolte and F. Würthner, Chem.
Comm., 2018, 54, 13763.
36 (a) G. Li, S. Wang, T. Liu, P. Hao, Z. Liu, F. Li, L.-M. Yang, Y.
Zhang, D. Li, S. Yang, J. Zhao, J. Li, H. Yan and B. Tang, J.
Mater. Chem. C., 2018, 6, 12601; (b) G. Li, Y. Zhang, T. Liu, S.
Wang, D. Li, J. Li, F. Li, L.-M. Yang, Z. Luo, C. Yang, H. Yan, P.
Hao, Q. Shang and B. Tang, J. Mater. Chem. C., 2018, 6,
11111.
37 (a) J. Yi, Y. Wang, Q. Luo, Y. Lin, H. Tan, H. Wang and C.-Q.
Ma, Chem. Comm., 2016, 52, 1649; (b) L. Yang, Y. Chen, S.
Chen, T. Dong, W. Deng, L. Lv, S. Yang, H. Yan and H. Huang,
J. Power Sources., 2016, 324, 538.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins