Heterologous perylene diimide arrays: Potential non-fullerene acceptors in organic solar cells

Article abstract of DOI:10.1039/c7tc03171h

A new family of perylene diimide (PDI) arrays, heterologous ones (di-PDI and tri-PDI), were designed and efficiently synthesized by Suzuki cross-coupling reactions using two heterologous PDI monomers with different positions of bay- and ortho-substitution, respectively. The compounds exhibit unique photophysical and electrochemical properties and were successfully applied in non-fullerene organic solar cells with a superior power conversion efficiency of 4.55% for tri-PDI.

Full text of DOI:10.1039/c7tc03171h

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PAPER
~
Nguyên T. K. Thanh, Xiaodi Su et al.
Fine-tuning of gold nanorod dimensions and plasmonic properties using
the Hofmeister effects
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ARTICLE
Heterologous Perylene Diimides Arrays: Potential Non-fullerene
Acceptors in Organic Solar Cells
Received 00th January 20xx,
Accepted 00th January 20xx
Helin Wang, Lingcheng Chen* and Yi Xiao*
DOI: 10.1039/x0xx00000x
A new family of perylene diimides (PDI) arrays, heterologous ones (di-PDI and tri-PDI), were designed and efficiently
synthesized by Suzuki cross-coupling reactions using two heterologous PDI monomers at different positions of bay- and
ortho-substitution, respectively. The compounds exhibit unique photophysical and electrochemical properties and were
successfully applied in non-fullerene organic solar cells with a superior power conversion efficiency of 4.55% for tri-PDI.
www.rsc.org/
1
. Introduction
Perylene diimides (PDI) arrays, an important type of PDI
derivatives, are constructed by PDI monomers coupling
directly through chemical bonds (singly-, doubly-, and triply-
1
linked), no other space linker units. Due to the favorable
combined properties of exceptional thermal- and photo-
stability, high molar extinction coefficient, and excellent
electron-transporting abilities, PDI arrays have been utilized in
2
a variety of applications in organic electronics. Among them, Fig. 1 PDI (a) and their homologous (b), heterologous (c) arrays.
the singly bonded ones have successfully used in organic solar
cells (OSCs) as electron acceptors because of their better years, the new catalytic systems of Ru- and Ir-based catalysts
3
matching energy levels, flexibility and twisted structures.
Especially, through the tailor-made molecular design and positions of PDI, which provides an opportunity to design and
have been developed to specifically catalyze the ortho-
8
synthesis, the singly bonded PDI dimer derivatives have synthesize this type of PDI derivatives. In addition, because of
realized great achievement in non-fullerene OSCs, of which the the large contribution to the conjugated structures and
power conversion efficiency (PCE) values are comparable or electron density distributions, substituent effects at the bay-
even superior to those of the corresponding classic fullerene positions are substantial, while the substitution at the ortho-
4
ones. Therefore, the molecular design is a crucial factor positions has been proved to be less effective to modify the
6
, 8, 9
affecting the different properties of the materials.
optical and electronic nature of the parent PDI.
Compared
As we know, the PDI monomer contains two different to the homologous ones, heterologous PDI arrays maybe own
reactive positions: ortho- (α-) and bay- (β-) positions (Fig. 1a). some unique photophysical and electrochemical properties.
Because the bay positions of PDI are more reactive toward Inspired by such purpose, we have a desire to achieve this type
electrophilic substitutions, bay-substituted PDI derivatives of heterologous PDI arrays to investigate the intrinsic
have been more highly studied than ortho-substituted PDI properties and photovoltaic properties.
5, 6
derivatives.
Up to now, all the reported PDI arrays are
Herein, we present the first examples of the heterologous
homologous ones, which are usually synthesized by efficient PDI arrays synthesized by Suzuki crossꢀcoupling reactions with
Ullmann coupling reactions using bay-halogenated PDI the two heterologous PDI monomers at the bay-position and the
7
monomers (Fig. 1b).
However, the corresponding orthoꢀposition, respectively. Their photophysical and
heterologous PDI arrays, especially for the ones coupled with electrochemical properties are characterized in details and give
bay-position and ortho-position of the PDI (Fig. 1c), are a great some important interesting phenomena. More importantly,
challenge to obtain because of the difficulty of the selective these molecules, as nonꢀfullerene electron acceptor materials,
reaction of the ortho-positions of PDI. Fortunately, in recent
have successfully applied in OSCs with the high PCE of 4.55%.
2
. Results and discussion
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Scheme 1 Synthetic routes of the important intermediates (a) and the target compounds of di-PDI and tri-PDI (b).
2
.1 Synthesis and characterization
As shown in Fig. 2a, three compounds exhibit similar UVꢀvis
absorption spectra in dilute dichloromethane solution and
strong absorption with the maximum molar extinction
Two heterologous PDI molecules (di-PDI and tri-PDI) were
prepared by efficient Suzuki crossꢀcoupling reactions between
the orthoꢀposition borate of the one PDI and the bayꢀposition
bromide of the other PDI (Scheme 1) with high yields of 69%
and 75% for di-PDI and tri-PDI, respectively. It should be
noted that, the homologous PDI arrays are usually synthesized
by the classical Ullmann coupling reactions with the dihalogenꢀ
or tetrahalogenꢀsubstituted PDI monomers. As a result, a series
of homologous PDI arrays with different amount of oligomers
4
4
5
ꢀ1
ꢀ1
coefficients of 9.0×10 , 9.0×10 , and 1.2×10 M cm for N, N'ꢀ
bis(1ꢀethylpropyl)peryleneꢀ3,4,9,10ꢀtetracarboxylic acid
diimides (PDI) (Scheme 1 di-PDI, and tri-PDI, respectively.
)
,
Compared with that of PDI (524 nm), the maximum absorption
peaks of di-PDI (529 nm) and tri-PDI (530 nm) only occur a
little red shift with 5 nm and 6 nm because of the enlarged
conjugation, which indicate that this method of connection with
orthoꢀposition and bayꢀposition almost retains PDI’s inherent
absorption property. In thin films (Fig. 2b), every absorption
spectra show a relatively broad absorption of 400ꢀ600 nm with
two peaks at 497 and 538 nm, 498 and 535 nm, 496 and 533 nm
7
are obtained in oneꢀpot synthesis. However, this method is
only suitable for the synthesis of homologous PDI arrays, not
for the heterologous ones. In addition, it is very difficult to
obtain a single PDI array by the column chromatography from
the series of oligomers. By contrast, the Suzuki crossꢀcoupling
reactions, which were used in our synthesis, are suitable for not
only homologous PDI arrays but also heterologous ones.
Moreover, the different alkyl or aryl groups connected with
imide position of PDI would affect the charge transport,
solubility, and the morphology of the thin films, and further
determining their optoelectronic properties and device
for PDI, di-PDI, and tri-PDI, respectively. Although the
corresponding maximum peaks in films occur some red shifts
relative to those in solution because of the intermolecular
interactions, the values of the red shift are becoming small from
1
4 nm for PDI to 3 nm for tri-PDI, which reveal that the
intermolecular interactions are weakened. More importantly,
the ratio of the two maximum peaks have changed a lot, which
illustrate that the morphology of molecular aggregation has also
changed greatly. In addition, it is important to note that for
PDI, the maximum absorption in solution is the 0ꢀ0 peak, but in
the thin film, the maximum absorption is the 0ꢀ1 peak because
of the very strong intermolecular πꢀπ packing. However, from
di-PDI to tri-PDI in thin film, the peaks of 0ꢀ1 gradually
weaken while the peaks of 0ꢀ0 become more intense, which
reveals that the strong intermolecular aggregation has been
efficiently inhibited. All these results could be attributed to the
reason that the dimer and trimer format the stereo conjugated
framework in which the steric hindrance results
1
0
performance. Therefore, we chose two different alkylꢀ
2
functionalized (3ꢀpentyl for PDI and 8ꢀpentadecyl for PDI )
PDI monomers to construct the heterologous PDI arrays. The
1
target compounds di-PDI and tri-PDI are highly soluble in
1
common organic solvents and fully characterized by HꢀNMR,
1
3
CꢀNMR spectroscopy and matrixꢀassisted laser desorption
ionization timeꢀofꢀflight (MALDIꢀTOF) mass spectrometry. In
addition, the compounds exhibit excellent thermal stability with
the decomposition temperatures (with 5% weight loss) of 350.1
o
o
C and 383.8 C for di-PDI and tri-PDI, respectively (see the
ESI†).
2
2
.2 Photophysical properties
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Fig. 2 UV-vis absorption spectra of PDI, di-PDI and tri-PDI in dichloromethane
(
-
1×10 ) (a) and in thin films (b).
5
Fig. 3 Cyclic voltammograms of di-PDI and tri-PDI in DCM (a) and the theoretical
in nonꢀcoplanar structures. As demonstrated by quantumꢀ calculation of LUMO (upper) and HOMO (blow) electron density distributions
with Gaussian DFT-B3LYP/6-31G.
chemical calculations using density functional theory (DFT)
(
6
see the ESI†), there exist big molecular planar distortions of
5 and 75 for di-PDI and tri-PDI, respectively, between the
compared to PDI, di-PDI and tri-PDI give the different electron
o
o
density distributions. What is more interesting is that the
LUMO are mainly located on the ortho-connected PDI units,
while the HOMO are mainly located on the bay-connected PDI
unit. The asymmetry in the location of the HOMO and LUMO
indicates that it is possible for charge transfer to occur from
the ortho-connected PDI unit to the bay-connected PDI unit,
PDI monomers. All these results indicate that these
heterologous PDI arrays could not only retain PDI’s unique
absorption characteristics, but also prevent the strong
intermolecular aggregation.
2
.3 Electrochemical properties
7
d
The cyclic voltammetry (CV) was employed to investigate their while it is not found in the homologous ones. The calculated
electrochemical properties (Fig. 3a). The compounds di-PDI LUMO levels of -3.64, -3.85 and -3.84 eV for PDI di-PDI, and
,
and tri-PDI exhibit five and three one-electron reduction tri-PDI, respectively. Although the calculated LUMO energy
waves in dichloromethane, which are more than that of PDI levels are slightly higher than those of the observed ones, the
with the two reduction waves. With the expansion of π- regularity of the values is consistent with the experimental
conjugated system, the first reduction potentials of PDI arrays data.
undergo a positive shift from -1.16 V for PDI to -1.07 V for di- 2.4 Photovoltaic properties
PDI, and to -1.09 V for tri-PDI, indicating the increase of the
In order to estimate the photovoltaic properties, using the two
PDI derivatives as electron acceptors, nonꢀfullerene OSCs were
fabricated with an inverted device architecture of
electron-accepting abilities. From the onset reduction
potentials, the lowest unoccupied molecular orbital (LUMO)
levels are estimated to be -3.92, -4.01, and -3.99 eV for PDI
, di-
ITO/ZnO/PTB7ꢀTh: di-PDI or tri-PDI (1:1)/MoO /Al, where
3
PDI, and tri-PDI, respectively.
ITO is indium tin oxide, ZnO and MoO were used as the n and
3
To obtain further insights into the electronic structures of
PDI di-PDI and tri-PDI, their geometries were optimized by
pꢀtype interfacial layers, respectively, to facilitate charge
,
DFT calculations at B3LYP/6ꢀ31G level. As shown in Fig. 3b,
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-2
of 9.36 mA cm , an open circuit voltage (VOC) of 0.661 V, and a
fill factor (FF) of 41.1%. At the same condition, the other
device based on PTB7-Th:di-PDI gives a relatively low PCE of
-
2
1
.95% with a JSC of 7.08mA cm , a VOC of 0.673 V, and an FF of
0.8%.
4
To further enhance the performance of devices, thermal
annealing process and some additives such as 1, 8-
diodooctane (DIO), chloronaphthalene (CN), and diphenyl
ether (DPE) are often used to improve the morphology of the
blend films. In our system with the optimal D/A weight ratio of
1
:1 (Table S2 and Fig. S5) (see the ESI†), when the thermal
annealing temperature is 160 °C, the device exhibits the
dominant device performance with a PCE of 3.94%. Then when
utilizing different amount CN as the additive, all the blend
films have obtained the optimal photovoltaic performance,
while the PCEs adding DIO and DPE are not improved (Table S3
and Fig. S6) (see the ESI†). It is found that the addition of 2%
CN can dramatically improve the J of devices from 9.36 to
SC
-
2
1
3.41 mA cm , accompanied by slight increase of the V and
OC
FF values. Therefore, the device based on PTB7-Th:tri-PDI (1:1)
with 2% CN additive shows the best performance: J of 13.41
SC
-2
mA cm , V of 0.713 V, FF of 40.0%, and PCE of 3.82%. At the
OC
same time, the device based on PTB7-Th:di-PDI also gives the
-2
improved PCE of 2.68% with a JSC of 9.98 mA cm , a V of
OC
0.661 V, and an FF of 40.6% (Table S4 and Fig. S7) (see the
ESI†). Finally, combined with thermal annealing (160 °C) and
the additive of 2% CN (Fig. 4a and Table 1), the devices exhibit
the best photovoltaic performance with a PCE of 4.55%, a J of
SC
-
2
1
2
2.61 mA cm , a V of 0.751 V, an FF of 48.1% and a PCE of
OC
-2
.84%, a JSC of 10.51 mA cm , a VOC of 0.661 V, an FF of 40.9%
respectively. In
for PTB7-Th:tri-PDI and PTB7-Th:di-PDI
,
Fig. 4 (a) J−V curves of the OSCs based on di-PDI (red lines) and tri-PDI (blue
lines) without (open symbols) and with 2% CN (solid symbols) and (b) the addition, although the homologous PDI trimer array has been
corresponding EQE spectra of the devices without (open symbols) and with 2%
CN (solid symbols).
synthesized in one-pot synthesis, it is very difficult to obtain a
single PDI trimer array by the column chromatography from
transport and collection. PTB7-Th, which has complementary the series of oligomers and its OSCs device performance was
7
absorption with the electron acceptors (see the ESI†) and well not reported. The detailed comparison of the homologous
matched energy levels, was chosen as the electron donors. Fig. and heterologous PDI arrays would be a very interesting work
1
1
4
a
and Fig. S4-S8 (see the ESI†) show the current density- to investigate, and the further studies on the comparison are
voltage (J-V) curves, and the photovoltaic performance data under way and will be presented in a forthcoming paper.
are listed in Table 1 and Table S1-S5 (see the ESI†) for a clear
The high JSC values of the devices with 2% CN additive can be
comparison. Firstly, the devices with varying PTB7-Th:di-PDI confirmed from their external quantum efficiency (EQE) curves
or tri-PDI) mass ratio from 1.5:1 to 1:1.5 were prepared and of the optimized devices (Fig. 4b). The devices show significant
tested. The device based on PTB7-Th:tri-PDI with 1:1 blend photo-to-current responses in the range of 300-800 nm, which
(
ratio shows an optimized average PCE of 2.54% with a JSC
agrees well with their absorption spectra of the donor and
acceptor materials (Fig. S3). After the additive processing, the
J
SC values are much higher than those of the primitive ones.
Table 1 Photovoltaic properties of the OSCs based on PTB7-Th:tri-PDI (or di-PDI
)
-
1:1 under the illumination of AM 1.5G, 100 mW cm .
2
Especially, for tri-PDI-based devices processed with 2% CN,
=
high EQE values over 50% are observed in a wide range of 450-
7
50 nm, with the peak values about 60% at 520 and 630-680
Add.
Temp.
o
[ C]
Jsc
-2
[mA cm ]
Voc
[V]
FF
PCE
[%]
nm. Therefore, tri-PDI exhibits the best device performance
because of the higher JSC values, which is attributed to the
stronger light absorption property. The integrated short circuit
current from EQE spectra is consistent with experimental data
obtained from the J−V measurement with a small deviation of
less than 5%.
Devices
[
vol.]
[%]
no
25
160
25
7.08
0.673
0.661
0.661
0.751
40.8
40.9
41.2
48.1
1.95
2.84
2.54
4.55
di-PDI
tri-PDI
2
2
% CN
no
10.51
9.36
% CN
160
12.61
4
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Fig. 6 AFM height images of the active layers based on PTB7-Th:di-PDI blend
without (a) and with (c) 2% CN additive, PTB7-Th:tri-PDI blend without (b) and
with (d) 2% CN additive.
and more balanced carrier transport of the blend film can
partially explain the better solar cell performance observed in
the tri-PDI OSCs than those of the di-PDI ones.
2
.6 Active layer morphology
The nanoscale phase-separation morphology also plays an
important role on the performance of the OSC devices. As
shown in Fig. 6, the blend films without treatment based on
PTB7-Th:di-PDI and PTB7-Th:tri-PDI both show large-size
phase- separated domains, and the root-mean-square (RMS)
roughness are 14.4 and 10.3 nm, respectively. After the
optimization of thermal annealing and additive processing, the
surface of the blend films becomes smoother with the RMS of
Fig. 5 Current density-voltage curves of the electron- (a, b) and hole-only (b)
devices. The lines with symbols are the measured values, and the lines without 6.1 and 3.2 nm for PTB7-Th:di-PDI and PTB7-Th:tri-PDI blends,
symbols are the theoretical fitting values.
respectively. Especially, the surface of PTB7-Th:tri-PDI blends
gives the favorable morphology and small-size phase
2
.5 Charge Mobilities
separation, which are in accordance with the much better
To further investigate the relationship of structure-properties-
performance of materials, the space-charge-limited current
performance of the PTB7-Th:tri-PDI device.
(SCLC) method was used to measure the hole and electron
mobilities with the device structures of ITO/PEDOT:PSS/Active
1
3
. Conclusions
2
layer/MoO
3
/Al and ITO/ZnO/Active layer/Ca/Al, respectively.
In summary, a new family of PDI arrays, heterologous PDI
oligomers, were designed and synthesized through efficient
Suzuki cross-coupling reactions between the ortho-position
borate of the one PDI monomer and the bay-position bromide
of the other PDI monomer. The absorption spectra revealed
that the two compounds not only retain the prototype PDI’s
intrinsic characteristics of strong absorption in visible light
region, but also could prevent the strong intermolecular
aggregation in thin films due to the stereo conjugated
molecular configurations. In electrochemical characterization,
di-PDI and tri-PDI exhibited more negative LUMO levels of
about -4.0 eV, which are slightly lower than that of PDI. A very
interesting result is that, for the heterologous PDI arrays, there
may be existing intramolecular charge transfer from one PDI to
the other PDI unit. Used the two compounds as electron
acceptors, the non-fullerene OSCs device based on tri-PDI gave
a superior performance up to 4.55%. All these results indicate
In the pure films (di-PDI or tri-PDI) SCLC electron-only devices
-4
(
Fig. 5a), tri-PDI gives a higher electron mobility of 3.78×10
2
-1 -1
-4
2
-1 -1
cm V s than that (2.59×10 cm V s ) of di-PDI. In their
blend film SCLC devices (Fig. 5b), the high hole mobilities of
-5
-5
.39×10 and 8.69×10 cm V s were obtained for PTB7-
2
-1 -1
8
Th:di-PDI and PTB7-Th:tri-PDI blend films, respectively. And in
their electron-only devices, the relatively low electron
-5
-5
2
-1 -1
mobilities of 1.11×10 and 1.94×10 cm V s were obtained
for PTB7-Th:di-PDI and tri-PDI blend film, respectively.
Compared the hole mobilities with the electron ones, the
formers are much higher than those of the latter
corresponding ones. And the ratio of hole/electron mobilities
(μ /μ ) are 7.6 and 4.5 for PTB7-Th:di-PDI and PTB7-Th:tri-PDI
h e
blend film, respectively. Obviously, besides of the higher
electron mobility of pure tri-PDI, the higher carrier mobilities
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that developing heterologous PDI derivatives have provided (Newport USA, Model: 94023A) with an AM 1.5 filter in
the other way to investigate the non-fullerene electron ambient air. The IPCE characterization of all devices was
acceptors for high efficiency OSCs.
performed in ambient air by a Hypermono-light (SM-25, Jasco
Co. Ltd., Japan). A calibrated Si photodiode (818-UV Newport)
was used as a reference in order to determine the intensity of
the light incident on the device, allowing the IPCE spectrum to
be deduced.
4
. Experimental section
Materials and General Methods
SCLC Devices fabrication and testing
−2
The ITO glass plates with 15 Ω cm resistor were cleaned in a
All reagents were purchased from Aldrich or Acros and used
without further purification. Solvents for chemical synthesis
were purified according to the standard procedures. All
chemical reactions were carried out under an inert
atmosphere. The indium-tin oxide (ITO) on glass was
purchased from Xiangcheng Science and Technology Co. Ltd.
All chemical reactions were carried out under an inert
atmosphere.
sonication bath in acetone, isopropyl alcohol and deionized
water sequentially, dried by blowing nitrogen, and then
2
treated with O plasma for 15 min before use. For the
electron-only devices: a thin layer (~25 nm) of ZnO sol-gel was
spin-coated at 4,000 rpm. for 40 seconds onto ITO glasses and
o
annealed at 200 C in ambient condition for one hour then
transferred into glove box immediately. Active layers were
spin-coated using the prepared solutions at 1000 rpm. for 30
seconds in a glove box, and the thickness is about 300 nm.
After that, the substrate was transferred to a vacuum thermal
evaporator, followed by deposition of the Ca/Al (10 nm/100
1
13
H and C NMR spectra were recorded using a 500 MHz
Bruker in CDCl at 293 K using TMS as a reference. Accurate
3
mass correction were measured with matrix-assisted laser
desorption-ionization time-of-flight (MALDI-TOF) mass
spectrometer (MALDI micro MX). UV-vis spectra were
measured with UV-vis spectrophotometer (Model HP8453) in a
-4
nm) cathode at a base pressure of 4 × 10 Pa. And for the
hole-only devices: a thin layer (~45 nm) of PEDOT:PSS was
spin-coated at 4,000 rpm. for 40 seconds onto ITO glasses and
o
annealed at 120 C in ambient condition for 30 min. then
1
cm quartz cell. Cyclic voltammograms (CVs) were recorded
on a BSA100B/W electrochemical workstation using glassy
carbon discs as the working electrode, Pt wire as the counter
transferred into glove box. Active layers were spin-coated
using the prepared solutions at 1000 rpm. for 30 seconds in a
glove box, and the thickness is about 300 nm. After that, the
substrate was transferred to a vacuum thermal evaporator,
electrode, Hg/Hg
scanning rate
tetrabutylammoniumhexafluorophosphate (Bu
in dichloromethane was employed as the supporting
electrolyte, which was calibrated by the
ferrocene/ferroncenium (Fc/Fc ) as the redox couple. The
2
Cl
2
electrode as the reference electrode at a
of 0.1 V/s. 0.05
NPF ) dissolved
M
4
6
3
followed by deposition of the MoO /Al (10 nm/100 nm)
-4
cathode at a base pressure of 4 × 10 Pa. All SCLC devices were
+
characterized with a computer-controlled Keithley 2420 source
+
13
energy of Fc/Fc is 5.08 eV relative to vacuum.
Thermogravimetric Analysis (TGA) were carried out using a
measure unit.
Synthesis
o
Mettler Toledo TGA/SDTA 851e at a heating rate of 10 C min
-1
-
under nitrogen flow of 20 mL min .
1
PTB7-Th is purchased from Solarmer Materials Inc., while
other commercially available reagents were purchased from
Sigma Aldrich, Alfa Aesar Co., TCI chemical Co., Thermo Fisher
Scientific Inc. and used without further purification unless
Geometry optimizations were optimized by the density
functional theory (DFT) at the B3LYP/6-31G level. All the
calculations were performed using the Gaussian 09 program.
2
otherwise stated. Considering the mixture of 2Br-PDI , the
To simplify the calculation, alkyl chains were replaced by CH
3
target molecule tri-PDI is also a mixture. In order to the
facilitation of the discussion, we use the one structure to
instead.
groups. AFM measurements were performed in a tapping
mode. All film samples were spincasted on ITO/ZnO substrates
with the same conditions of the corresponding OSC devices.
OSC Devices Fabrication and Measurements
Compound
N,N'-Bis(1-ethylpropyl)perylene-3,4,9,10-
PDI): A mixture of 3,4,9,10-
tetracarboxylic acid bisimide
(
The ITO glass plates were cleaned in a sonication bath in
acetone, isopropyl alcohol and deionized water sequentially,
Perylenetetracarboxylic acid dianhydride (1 g, 2.55 mmol), 3-
aminopentane (0.75 mL, 6.44 mmol) and imidazole (10 g, 0.15
o
mol) was stirred under nitrogen at 140 C for 4 hours. After
dried by blowing nitrogen, and then treated with O
2
plasma for
15 min before use. About 25 nm thick ITO-modifying layer of
that, water was added and the mixture was extracted with
dichloromethane. The organic layers were washed with brine
ZnO was spin-coated on top of ITO and then baked for 30 min
at 200 °C. Then the PTB7-Th and di-PDI (or tri-PDI) blend liquid
was spin-coated on the ZnO layer to get an 80 nm thick film.
4
and dried over MgSO . The solvent was removed under
reduced pressure, and the residue was purified by silica gel
column chromatography with dichloromethane as eluent.
Compound PDI was obtained in 90 % yield (1.2 g, 2.26
3
Finally, MoO and Al layers were evaporated on top of the
active layer. The device area, the overlap section between the
2
ITO and Al electrodes, was about 7 mm .
1
o
mmol). H NMR (500 MHz, CDCl
3
, 25 C): δ (ppm) = 8.82-8.67
The photocurrent–voltage (J-V) characteristics of the solar
cells were measured using a Keithley 2400 Source-measure
unit under illumination of a simulated sunlight (AM 1.5G,
(m, 4H), 8.60-8.57 (d, 2H), 8.56-8.55 (d, 2H), 5.09-5.03 (m, 2H),
2.23-2.19 (m, 4H), 1.96-1.91 (m, 4H), 0.93-0.91 (t, 12H).
-
2
1
00mW· cm ) provided by an Oriel Sol3A solar simulator
6
| J. Name., 2012, 00, 1-3
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Page 7 of 9
Jou Pr nl e aa ls oe fd Mo an to et r ai ad lj su s Ct hm ea mr g ii sn ts ry C
View Article Online
DOI: 10.1039/C7TC03171H
Journal Name
ARTICLE
Compound
N,N’-Bis(1-ethylpropyl)-2-(4,4,5,5-tetramethyl- Compound di-PDI: A mixture of B-PDI
1
(0.2 g, 0.31 mmol), and
1
,3,2-dioxaborolan-2-yl)-
1
2 2
perylene-3,4,9,10-tetracarboxylic Br-PDI (0.3 g, 0.34 mmol), Pd(dppf)Cl (30 mg, 0.04 mmol) and
4
1
acid bisimide (B-PDI ) : A mixture of PDI (1 g, 1.89 mmol), bis 1 M aqueous potassium phosphate (2 mL) in THF (10 mL) was
o
(
pinacolato) diboron (0.75 g, 2.95 mmol), [Ir(OMe)cod]
mg, 0.06 mmol) and tris (pentafluorophenyl) phosphine (120 the mixture was extracted with chloroform. The organic layers
mg, 0.24 mmol) in 5 mL of 1,4-dioxane was stirred under were washed with brine and dried over MgSO . The solvent
2
(38 stirred at 80 C for 8 hours. After that, water was added and
4
o
nitrogen at 110 C for 48 hours. The solvent was removed was removed under reduced pressure, and the residue was
under reduced pressure, and the residue was purified by silica purified by silica gel column chromatography with petroleum
gel column chromatography with dichloromethane as eluent. ether:dichloromethane =1:10 as eluent. Compound di-PDI was
1
was obtained in 45 % yield (0.56 g, 0.85 obtained in 69 % yield (0.28 g, 0.21 mmol). H NMR (500 MHz,
Compound B-PDI
1
1
mmol). H NMR (500 MHz, CDCl
o
o
3 3
, 25 C) : δ (ppm) = 8.67-8.65 CDCl , 25 C) : δ (ppm) = 8.86-8.85 (d, 1H), 8.80-8.78 (d, 1H),
(d, 1H), 8.58-8.56 (d, 3H), 8.54-8.51 (m, 2H), 8.46 (s, 1H), 5.09- 8.77-8.70 (m, 6H), 8.54-8.51 (d, 2H), 8.42-8.40 (d, 2H), 8.01-
4
1
C
.97 (m, 2H), 2.28-2.23 (m, 4H), 1.97-1.95 (m, 4H), 1.58 (s, 7.97 (d, 1H), 7.83-7.80 (d, 1H), 5.19-4.77 (m, 4H), 2.28-2.01 (m,
2H), 0.94-0.92 (t, 12H); MALDI-TOF-MS: Calcd for 8H), 1.95-1.74 (m, 8H), 1.25-1.22 (m, 40H), 0.90-0.83 (m, 24H);
-
13
o
40
H41BN
2
O
6
, 656.3058 [M ], found 656.3006.
C NMR (125 MHz, CDCl
63.39, 163.37, 147.98, 143.32, 141.37, 136.12, 134.82,
N,N'-Bis(1-heptyloctyl)perylene-3,4,9,10- 134.27, 133.50, 131.58, 131.08, 129.58, 129.32, 128.98,
tetracarboxylic acid diimide PDI ): A mixture of 3,4,9,10- 128.80, 128.55, 128.40, 127.93, 127.28, 126.48, 126.44,
3
, 25 C) : δ (ppm) = 164.77, 163.74,
1
Compound
(
2
Perylenetetracarboxylic acid dianhydride (1 g, 2.55 mmol), 8- 125.37, 123.72, 123.66, 122.97, 57.87, 57.80, 54.84, 54.66,
aminopentadecan (1.28 g, 5.63 mmol) and imidazole (15 g, 31.81, 31.73, 29.54, 29.42, 29.24, 29.23, 29.14, 27.00, 26.88,
o
.23 mol) was stirred under nitrogen at 140 C for 5 hours. 22.62, 22.55, 14.06, 14.01, 11.29; MALDI-TOF-MS: Calcd for
0
-
After that, water was added and the mixture was extracted
with dichloromethane. The organic layers were washed with
88 98 4 8
C H N O , 1338.7385 [M ], found 1338.7363.
brine and dried over MgSO
reduced pressure, and the residue was purified by silica gel and B-PDI
column chromatography with petroleum and 1 M aqueous potassium phosphate (2 mL) in THF (10 mL)
ether:dichloromethane =1:1 as eluent. Compound PDI
4
. The solvent was removed under Compound tri-PDI: A mixture of 2Br-PDI
2
(0.12 g, 0.13 mmol),
1
(0.2 g, 0.31 mmol), Pd(dppf)Cl
2
(23 mg, 0.03 mmol)
o
2
was was stirred at 80 C for 8 hours. After that, water was added
obtained in 93 % yield (1.92 g, 2.37 mmol). H NMR (500 MHz, and the mixture was extracted with chloroform. The organic
1
o
CDCl
3
, 25 C) : δ (ppm) =8.96-8.78 (m, 4H), 8.64-8.62 (d, 2H), layers were washed with brine and dried over MgSO
.56- 8.54 (d, 2H), 5.16-5.14 (m, 2H), 2.24-2.22 (m, 4H), 1.84- solvent was removed under reduced pressure, and the residue
.81 (m,4H), 1.60-1.10 (m, 40H), 0.92-0.88 (m, 12H). was purified by silica gel column chromatography with
4
. The
8
1
petroleum ether:dichloromethane =1:9 as eluent. Compound
1
N,N'-Bis(1-heptyloctyl)-1-bromo-perylene- tri-PDI was obtained in 75 % yield (0.17 g, 0.091 mmol). H
Compound
o
, 25 C): δ (ppm) = 8.86-8.76 (m, 8H),
3
,4,9,10-tetracarboxylic acid diimide
(
Br-PDI
2
) and N,N'-Bis(1- NMR (500 MHz, CDCl
3
heptyloctyl)-1,6-bibromo-perylene-3,4,9,10- tetracarboxylic 8.65-8.59 (m, 8H), 8.06-8.01 (m, 2H), 7.84-7.77 (m, 2H), 5.11-
acid diimide and N,N'-Bis(1-heptyloctyl)-1,7-bibromo- 5.07 (m, 4H), 5.06-4.78 (m, 2H), 2.29-2.25 (m, 8H), 1.97-1.92
perylene- 3,4,9,10-tetracarboxylic acid diimide
2
(2Br-PDI ): A (m, 8H), 1.76-1.73 (m, 8H), 1.25-1.18 (m, 40H), 0.95-0.77 (m,
1
3
mixture of PDI (1 g, 1.23 mmol), anhydrous potassium 36H); C NMR (125 MHz, CDCl , 25 C) : δ (ppm )= 164.48,
o
2
3
carbonate (3.4 g, 24.64 mmol) and bromine (5 mL, 0.1 mol) in 163.38, 147.17, 140.71, 136.15, 135.92, 134.92, 134.68,
o
chloroform (20 mL) was stirred at 70 C for 8 hours. The excess 134.37, 134.23, 133.65, 133.40, 132.75, 132.36, 130.93,
bromine was removed by adding aqueous Na
added and the mixture was extracted with chloroform. The 125.97, 124.05, 123.63, 120.63, 57.78, 54.72, 32.35, 32.21,
organic layers were washed with brine and dried over MgSO 31.75, 29.70, 29.46, 29.16, 26.89, 25.02, 24.85, 24.61, 22.57,
The solvent was removed under reduced pressure, and the 14.04, 11.32, 11.13, 10.98; MALDI-TOF-MS: Calcd for
2 3
SO . Water was 129.63, 129.58, 128.88, 128.42, 128.30, 126.54, 126.47,
4
.
-
residue was purified by silica gel column chromatography with
122 126 6
C H N O12, 1866.9434 [M ], found 1866.9447.
petroleum ether:dichloromethane =3:2 as eluent. Compound
1
was obtained in 41 % yield (0.41 g, 0.46 mmol), H
Br-PDI
2
o
Acknowledgements
NMR (500 MHz, CDCl
3
, 25 C) : δ (ppm) =9.79 (d, 1H), 8.92-8.70
m, 4H), 8.62 (d, 2H), 5.17-5.15 (m, 2H), 2.26-2.22 (m, 4H),
(
This work is supported by National Natural Science Foundation
of China (Nos. 21376038, 21421005, 21406027, and
1.85-1.81 (m,4H), 1.60-1.10 (m, 40H), 0.91-0.88 (m, 12H).
Compound 2Br-PDI
2
were obtained in 46 % yield (0.55 g, 0.57
2
2
1576040), National Basic Research Program of China (No.
013CB733702), Dalian Agency for Science and Technology
1
o
mmol), H NMR (500 MHz, CDCl
3
, 25 C) : δ (ppm) =9.49 (d,
H), 8.90 (d, 2H), 8.65-8.58 (m, 2H), 5.17-5.14 (m, 2H), 2.23-
.21 (m, 4H), 1.85-1.81 (m,4H), 1.60-1.10 (m, 40H), 0.92-0.88
2
2
(No. 2015R040), and the Fundamental Research Funds for the
Central Universities (No. DUT16RC(4)02).
(m, 12H).
Notes and references
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
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Journal of Materials Chemistry C
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View Article Online
DOI: 10.1039/C7TC03171H
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| J. Name., 2012, 00, 1-3
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Page 9 of 9
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/C7TC03171H
TOC
A new family of perylene diimides (PDI) arrays, heterologous ones, were efficiently
developed for non-fullerene organic solar cells with a superior PCE of 4.55%.