Influences of the number of 2-ethylhexylamine chain substituents on electron transport characteristics of core-substituted naphthalene diimide analogues

Article abstract of DOI:10.1039/d0nj05045h

We designed and synthesized a series of naphthalenediimide (NDI) derivatives through core-substitution (coded as cNDI) with various number of 2-ethyl-hexylamine (EHA) chains at different positions. The molecular structure of cNDI derivatives such as cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA bearing one, two, three and four 2-ethyl-hexylamine chains, respectively, was confirmed by different spectroscopic techniques such as FTIR, 1H-NMR, 13C-NMR spectroscopy and mass spectrometry. Interestingly, the incorporation of different numbers of 2-ethyl-hexylamine on electron-deficient cNDI yields diverse photophysical and electrochemical properties. The change in the number of alkyl chains on the NDI core significantly influences the redox properties and the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels. The changes in the morphology of the spin-coated films before and after annealing are reorganized differently depending on the number of 2-ethyl-hexylamine topology proved by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The electron mobility of cNDIs was examined by following the standard protocol of the space-charge limiting current (SCLC) method. The NDI derivatives bearing various number of 2-ethyl-hexylamine chains at the NDI core after thermal treatment at 170 °C exhibited very good electron mobility of the order of 10-6 to 10-4 cm2 V-1 s-1. The observed electron mobility trends depend not only on the number of 2-ethyl-hexylamine substituents but also on the changes in thin-film morphology.

Full text of DOI:10.1039/d0nj05045h

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Influences of number of 2-ethylhexylamine chain substituents on
electron transport characteristics of core-substituted naphthalene
diimide analogues
Received 00th January 20xx,
Accepted 00th January 20xx
Shailesh S. Birajdar, a,e, † Samya Naqvi, b,† Kerba S. More,c Avinash L. Puyad,d Rachana Kumar,* b,e
Sidhanath V. Bhosale, *a,e Sheshanath V. Bhosale*c
DOI: 10.1039/x0xx00000x
We designed and synthesized a series naphthalenediimide (NDI) derivatives through core-substitution (coded as: cNDI) with
various number of 2-ethyl-hexylamine (EHA) chains at different positions. The molecular structure of cNDI derivatives such
as cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA bearing one, two, three and four 2-ethyl-hexylamine chain,
respectively is confirmed by different spectroscopic techniques such as FTIR, 1H-NMR, 13C-NMR spectroscopy and Mass
spectrometry. Interestingly, incorporation of different numbers of 2-ethyl-hexylamine on electron deficient cNDI yields
diverse photophysical and electrochemical properties. The change in number of alkyl chain on NDI core significantly
influences the redox properties and highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital
(LUMO) energy levels. The crystal packing and changes in morphology of the spin coated films before and after annealing
are reorganized differently depending on the number of 2-ethyl-hexylamine topology proved by scanning electron
microscopy (SEM) and X-ray diffraction (XRD) techniques. The electron mobility of cNDIs were examined following the
standard protocol of space-charge limiting current (SCLC) method. The NDI derivatives bearing various number of 2-ethyl-
hexylamine chain at NDI core with thermal treatment at 170 ºC exhibits very good electron mobility of the order of 10-6 to
10-4 cm2/Vs. The observed electron mobility trends are not only depends on number of 2-ethyl-hexylaminesubstituents but
also on the changes in thin-film morphology.
synthesized. Literature search revealed that development of n-
type organic electron-transport material lags far behind to that
of p-type semiconductors due to their instability, inferior
1. Introduction
Development of air-stable organic semiconductor materials
have attracted considerable attention for their potential
application as active layers or transport layer for flexible and
large-area organic electronics, organic light emitting diodes
(OLEDs), bipolar transistors, printed circuits, electronic papers,
optoelectronic sensors, organic solar cells and so on.1-8 To
fabricate p- and n-type semiconducting material various π-
conjugated chromophores have been designed and
performance and few other affairs.9-12 Many of the n-type
organic semiconductors (OSCs) exhibiting the limited structural
diversity, sensitivity to moisture, oxygen or light and device
performances.13,14 The n-type materials must exhibit strong
intermolecular π-π staking interaction in the solid state to
facilitate high electron mobility.15 The stability of n-type OSCs is
affected by the reasonably less deeper LUMO energy
levels.16Therefore, development of air-stable novel high-
performance n-type OSCs have become an important task for
the researchers and to overcome these limitations enormous
efforts have been dedicated to design and synthesize air-stable
n-type OSCs with low-lying LUMO.17,18 It was found that to
address this issue, various n-type OSCs have been designed and
a. Polymers and Functional Materials Division, CSIR-Indian Institute of Chemical
Technology, Hyderabad-500007, Telangana, India. Email: bhosale@iict.res.in
b. Advanced Materials and Devices Metrology Division, Photovoltaic Metrology
Group, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi
110012, India E-mail: rachanak.npl@nic.in ; rachanasinghchem@gmail.com
c. School of Chemical Sciences, Goa University, Taleigao Plateau, Goa-403206, India
E-mail: svbhosale@unigoa.ac.in
synthesized
benzothiadiazole,21,22 diketopyrrolopyrrole,23,24 isoindigo,25,26
bisthienoistain,27 dyes,28,29
rylene 7,7,8,8,-
such
as
fullerene
derivatives,19,20
d. School of Chemical Sciences, Swami Ramanand Teerth Marathwada University,
Nanded 431606, Maharashtra, India.
tetraycanoquinodimethane (TCNQ)30 etc. These building blocks
are used in small molecule semiconductors as well as in
polymers.
Recently, rylene diimide chromophores such as
pyromelliticdiimides (PyDIs), naphthalenediimide (NDIs), core-
substituted NDIs, and perylenediimides (PDIs) have been
e. Academy of Scientific and Innovative Research (AcSIR), Ghaziabad- 201002, Uttar
Pradesh, India
† First two authors contributed equally
1
Electronic Supplementary Information (ESI) available: [Scheme S1, FT-IR, H NMR,
13C NMR spectra and Mass & HRMS spectrum, XRD spectra, SEM images,
experimental conditions and device architecture with electron mobility properties,
DFT and TA-DFT calculations as well as theoretical absorption spectra available]. See
DOI: 10.1039/x0xx00000x
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extensively employed to fabricate efficient n-type electron-
transporting materials.28,31,32,33,34,35 Among these building
blocks, cNDIs are planar π-conjugated chromophores and have
been explored as promising n-type OSCs.32,34,36,37,38,39,40In order
to apply the NDI chromophores to device applications, much
efforts have been devoted to tune their optical, photophysical,
electrochemical and electronic properties by modulating at the
imide-/core- positions with π-conjugated systems, electron
withdrawing groups and alkyl chains.41,42,43 Moreover, when
core of the NDI is modified by a strong electron withdrawing
group, one can further lower the LUMO energy levels to
increase the air-stability of n-type materials and facilitate the
electron transport properties.44-47 The incorporation of alkyl
chain at nitrogen atom of the imide enabled smooth solution
processability and self-assembly due to good solubility.42,48,49
Sauvé group demonstrated that the NDI functionalization at
core tuned the optoelectronic properties of the chromophore
and their applications in non-fullerene solar cells.50 On the basis
of imide-/core-substitution strategy a series of novel NDI based
small molecules and polymers have been explored as n-type
semiconductor with high electron mobility under inert
atmosphere and under vacuum was achieved.51 Moreover, it is
notable that there are very few examples have been reported
in the literature in which how the modification of the side chain
structure, length, and branching significantly influences the
solubility, packing structure and performance of the carrier
mobility device. Nevertheless, Ma et al. have reported the first
time effect of alkyl chain length on stacking and charge transfer
mobility and also demonstrated that the short alkyl chain at the
diimide position of the NDI and shown to be useful for charge
2. Experimental Section
View Article Online
DOI: 10.1039/D0NJ05045H
2.1. Thermogravimetric Analysis: Thermogravimetric analysis
(TGA) measurement was performed using a TA instruments
Q500 TGA under flowing nitrogen gas at a heating rate of 10°C
per minute up to 800°C.
2.2. UV-vis Measurements for Solution: UV-vis absorption
measurements were performed on UV-vis-1800 Shimadzu
spectrometer using 1 cm path length quartz cuvette. A 300 μL
aliquot of NDI-1EHA, NDI-1EHA, NDI-2EHA, NDI-3EHA and NDI-
4EHA (110-3 M stock solution) were transferred to a vial and
made up to a final volume of 3 mL (1 × 10-4 M) in
dichloromethane. The solutions were allowed to equilibrate for
2h prior to their spectral measurements. For thin film
measurements, samples were prepared using spin coating
method.
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2.3. Cyclic Voltammetry Measurements: The solutions of NDI-
1EHA, NDI-1EHA, NDI-2EHA, NDI-3EHA and NDI-4EHA and
ferrocene (Fc) in dichloromethane were deoxygenated by
bubbling nitrogen gas. The electrolyte tetra-n-butylammonium
hexafluorophosphate (0.1 M) was used as supporting
electrolyte. The CV measurements were performed at room
temperature by using a Power Lab ML160 potentiostat
interfaced via a Power Lab4/20 controller to a PC running E-
Chem for Windows version 1.5.2. Cyclic voltammograms.
Platinum is used as a working electrode with saturated calomel
electrode (SCE) is a reference electrode, auxiliary electrode: Pt
wire. Fc was used as the internal reference; scan rates: 0.100
mV/s, at 20 °C.
transport.52
Furthermore,
McNeill
and
co-workers
demonstrated the effect of alkyl side-chain substituent and
length on the thin-film morphology and solution processed NDI
chromophores OFETs device performance.53 However, to the
best of our knowledge, the number of alkyl chain and position
of substitution at core of the NDI followed by their n-type
semiconducting properties are not investigated till to date.
Herein, we investigate the influence of the number of alkyl
i.e. 2-ethyl-hexaylamine chain substitution and their position at
core of the NDI over electrochemical and electron transport
properties. Typically, we have synthesized a series of NDI-based
chromophores i.e. cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and
cNDI-4EHA, which is substitution at the core with one, two,
three and four 2-ethyl-hexylamine chains, respectively (FIg. 1).
The optical and electrochemical properties evaluated by means
of UV-vis and cyclic voltammetry, respectively. The thin-film
morphology is studied by employing SEM and XRD techniques.
The structure-property relation has been investigated at
2.4. Scanning Electron Microscopy (SEM) Measurements: Firstly,
the silicon wafer substrate was cleaned by rising in acetone and
ethanol then Milli Q water. Then the sample sputter was coated
with gold for 10 s at 0.016 mA Ar plasma (SPI, West Chester,
USA) using a FEI Nova NanoSEM (Hillsboro, USA) operating at
high vacuum which provided direct visualization of the material.
The samples were prepared by solvent evaporation and spin
coating methods.
2.5. X-ray Diffraction Measurements: The NDI-1EHA, NDI-1EHA,
NDI-2EHA, NDI-3EHA and NDI-4EHA in the DCM solvent
mixtures were used for XRD measurements. Then precipitates
of NDI-EHAs were dropped on the silicon wafer and dried at 40
oC for 4 h, this process was repeated for 3 times. The thin film
of NDI-EHAs was prepared using spin coating techniques.
different temperatures to enable the effect of temperature and Structure and crystallinity were analysed on a X'Pert PRO PAN
the numbers of 2-ethyl-hexylamine chain on thin-film
morphology, electrical conductivity and electron mobility of
NDIs. The charge transport properties were calculated using
space-charge limiting current (SCLC) model by fabricating
alytical machine with a 0.15405 nm Cu-Kα radiation source.
2.6. Device Fabrication
electron-only devices. The best performance was produced NDI 2.6.1. Electron Transport Studies:41,49,60 The charge carrier
bearing three 2-ethyl-hexylamine chain i.e., cNDI-3EHA exhibits
mobility of all the materials was investigated by fabricating
electron only device. The ITO coated glass substrates were
ultrasonically cleaned with soap solution, acetone, isopropyl
-4
.
the maximum electron mobility of 2.69x10 cm2V-1s-1
2 | J. Name., 2012, 00, 1-3
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which corresponds to the NDI-Ar-H carbon (FIg. S3). Compound
NDI-4Br is a dark yellow solid. H NMR spectra showed the
absence of NDI-Ar peak in aromatic region (FIg. S4).
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alcohol for 10 minutes and dried in a vacuum oven. The zinc
oxide (ZnO) precursor solution was spin coated on cleaned ITO
substrates and then baked on hot plate at 250 °C for 30 minutes.
The active layer solution of all the NDI materials (40 mg/mL) in
chlorobenzene was spin-coated on top of ZnO coated ITO
substrate with annealing at 170 °C for 15 minutes. Finally, the
substrates were loaded into a thermal evaporator for the
deposition of the metal electrode, i.e., a 100 nm Al layer was
deposited on top of the NDI layer under high vacuum. The I–V
characteristics were tested at room temperature under dark
condition using a computer controlled Keithley 2420 source
measure unit.
View Article Online
DOI: 10.1039/D0NJ05045H
1
Furthermore, the synthesis of core-substitution of NDI-3Br
and NDI-4Br with 2-ethyl-hexylamine was performed as a
nucleophilic substitution reaction at 140 °C for 15 h and 18 h,
respectively, to produce cNDI-3EHA and cNDI-4EHA as
illustrated in Scheme 1. Compound cNDI-3EHA is a blood red
sticky liquid. The FT-IR spectra of compound cNDI-3EHA was
measured and displayed in Fig. S14. As illustrated in Fig. S14, the
absorption peak appeared at 1637 cm-1 is ascribed to imide
carbonyl group stretching vibrations and those located at 1281
cm-1 is corresponding to C-O stretching vibrations. The
absorption peak located at 3450 cm-1 is ascribed to N-H
stretching vibrations. As seen in Fig. S14, the stretching
vibration frequency of C-H exhibit peaks at 2864 cm-1 and 2952
cm-1. 1H/13C NMR spectra displayed the existence of peak at δ
7.77 ppm/126.25 ppm, which corresponds to the NDI-Ar
hydrogen and carbon atoms, respectively (FIg. S15/S16).
MALDI-TOF spectrometry gave m/z peaks at 871.56 [M+H]+ (FIg.
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3. Results and Discussion
NDI-1EHA NDI-2EHA
NDI-3EHA NDI-4EHA
O
O
N
N
O
O
1
S17). Chromophore cNDI-4EHA is a dark green sticky liquid. H
R1
R4
R3
R2
NMR spectra of cNDI-4EHA does not exhibits any aromatic
proton peak (FIg. S19) and in MALDI-TOF spectrum m/z peak at
998.61 corresponds to [M]+ ion (FIg. S21) appeared confirms the
formation of complete core nucleophilic substitution. All the
synthesized compounds i.e., cNDI-1EHA, cNDI-2EHA, cNDI-
3EHA and cNDI-4EHA were utilized for further thermal, optical,
electrochemical characterization and device fabrication.
Chen et.al., have reported core substituted tetraamino-NDI
showing high HOMO and LUMO energy levels and behaving
more like electron donor. However, in the present work, all the
four NDIs show comparatively deeper HOMO and LUMO energy
levels as required for stable n-type OSCs.42,49
NDI-1EHA: R2, R3, R4 = H and R1 = 2-ethyl-1-hexylamine
NDI-2EHA: R3, R4 = H and R1, R2 = 2-ethyl-1-hexylamine
NDI-3EHA: R4 = H and R1, R2, R3 = 2-ethyl-1-hexylamine
NDI-4EHA: R1, R2, R3, R4 = 2-ethyl-1-hexylamine
Fig.1Chemical structures of the naphthalenediimide derivatives cNDI-1EHA, cNDI-
2EHA, cNDI-3EHA and cNDI-4EHA.
3.1. Development and synthesis of NDI based molecular
architectures
Two known derivatives cNDI-1EHA and cNDI-2EHA were
prepared from 1,4,5,8-naphthalene dianhydride in three steps
following reported literature procedure (see ESI Scheme S1).54a
Interestingly to quote here, this is first time we were able to
synthesize tri-bromo along with tetra-bromo substituted
1,4,5,8-naphthalene dianhydride (NDA), typically, we obtained
compounds NDA-3Br and NDA-4Br54b by reacting NDA with
dibromohydantoin (DBH) in concentrated sulphuric acid (H2SO4)
at 90 °C (Scheme 1).
The synthesis of compounds NDI-3Br and NDI-4Br were
achieved by the two step reaction sequence via the amide
bearing bromo-substituted naphthalene-dicarboxylic acids1
and 2. Thus, the reaction of NDA-3Br and NDA-4Br with 2-ethyl-
1-hexylamine in acetic acid at 90 °C gave the corresponding
products
1 and 2(Scheme 1). Subsequent reaction of
compounds 1 and 2with phosphorus tribromide (PBr3) in
toluene at reflux temperature gave two products in various
proportions i.e. NDI-3Br (20% yield) and NDI-4Br (60% yield)
depending on the reaction conditions (see the experimental
1
section). Compound NDI-3Br is a golden yellow solid. H NMR
spectra indicated the existence of single NDI-Ar proton peak
signal at δ 9.00 ppm (FIg. S2). 13C NMR pointed the bromine
substituted NDI-Ar carbon (three) peaks at δ 128.40 ppm,
127.78 ppm and 125.31 ppm, whereas, peak at δ 139.20 ppm,
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Br
N
View Article Online
DOI: 10.1039/D0NJ05045H
O
N
O
O
O
O
O
Br
O
O
O
O
O
O
O
O
O
O
O
O
O
DBH
2-ethyl-1-hexylamine
acetic acid
Br
Br
Br
Br
Br
Br
Br
H2SO4, 90 o
24 h
C
90 oC, 8 h
O
8
9
NDA
NDA-4Br
NDA-3Br
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O
O
N
N
O
O
OO
NH
OO
HO
Br
O
O
N
O
O
HO
NH
Br
PBr3
Toluene
Br
Br
Br
Br
Br
Br
Br
Br
Reflux, 8 h
Br
HN
Br
Br
HN
Br
OH
OH
OO
OO
N
NDI-3Br
(20%)
NDI-4Br
(60%)
2
-
e
t
h
y
l-
1
2
1
-
e
x
y
la
m
in
e
Fig. 2 Thermogravimetric analysis (TGA) of (a) cNDI-1EHA (red line), (b) cNDI-2EHA
140 oC, 15 h
(blue line), (c) cNDI-3EHA (green line) and (4) cNDI-4EHA (black line).
140 oC, 18 h
3.4. Photophysical properties
NH
NH
O
N
O
The UV-vis absorption properties of cNDI-1EHA, cNDI-2EHA,
cNDI-3EHA and cNDI-4EHA were studied in dichloromethane
(DCM) solution (1.0 × 10-4 M), a solvent of moderate polarity
(FIg. 3a), and also in thin-film form (FIg. 3b). The absorption data
are summarized in Table 1. cNDI-1EHA has two absorption
bands at λmax = 500 nm (shoulder) and 532 nm (ε = 1.06 × 10-4
M-1cm-1). The UV-vis absorption of cNDI-2EHA shows three
small absorption peaks at 420 nm(ε = 0.68 × 10-4 M-1cm-1), 433
nm(ε = 0.67 × 10-4 M-1cm-1), 470 nm (ε = 0.67 × 10-4 M-1cm-1) and
one shoulder band at 566 nm (ε = 1.43 × 10-4 M-1cm-1) along with
strong peak at 603 nm(ε = 2.31 × 10-4 M-1cm-1). cNDI-3EHA
display an absorption maximum at around 624 nm (ε = 3.26 ×
10-4 M-1cm-1) with shoulder band at 578 nm(ε = 1.73 × 10-4 M-
N
O
O
HN
HN
NH
NH
HN
O
N
O
O
N
O
NDI-4EHA
NDI-3EHA
50%
40%
Scheme 1. Synthesis of NDI-3Br, NDI-4Br-cNDI-3EHA and cNDI-4EHA.
3.2. Thermal stability
The thermogravimetric analysis (TGA) experiments were
performed under nitrogen atmosphere, in the temperature
range from 25 ºC to 800 ºC, at a heating rate of 10 ºC/min. The 1cm-1). The UV-vis absorption spectra of cNDI-4EHA exhibit at
thermal stability and decomposition behaviour of cNDI-1EHA,
cNDI-2EHA, cNDI-3EHA and cNDI-4EHA are illustrated in FIg. 2a,
434 nm (shoulder)(ε = 0.65 × 10-4 M-1cm-1), 460 nm (ε = 0.86 ×
10-4 M-1cm-1) and prominent peak at 651 nm(ε = 2.26 × 10-4 M-
1cm-1). In DCM solvent, cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and
b, c and d, respectively. The 5% weight loss of cNDI-1EHA, cNDI-
cNDI-4EHA show strong absorption from 400 nm to 730 nm,
which is attributed to the intramolecular charge transfer (ICT)
transitions from the 2-ethyl-1-hexylamine substituent to NDI
ring system. The photoabsorption band of cNDI-2EHA, cNDI-
3EHA and cNDI-4EHA shows pronounced bathochromic shift of
78 nm, 94 nm and 121 nm, respectively, as compared to the
absorption band of NDI-1EHA appeared at 530 nm (FIg. 3a). This
red-shift in absorption peak is due to the increase in number of
2-ethyl-1-hexylamine chain at NDI core leading to the strong ICT
excitation. For solid state UV-vis absorption study, thin-film of
the NDIs were deposited via spin coating on glass substrate. The
UV-vis absorption of NDI-1EHA exhibits absorption peaks at 466
nm (shoulder), 505 nm and 532 nm. NDI-2EHA has three small
absorption bands at 412 nm, 439 nm and 468 nm along with one
broad shoulder peak at 564 nm and a strong band appeared at
600 nm. cNDI-3EHA show an absorption peaks at 538 nm (broad
shoulder) and two strong peaks at 578 nm and 614 nm. The
spectral absorptions of the cNDI-4EHA appeared at 434 nm
(small shoulder), 468 nm (small), broad shoulder at 595 nm and
strong band at 645 nm. As illustrated in FIg. 3b, the broadening
2EHA, cNDI-3EHA and cNDI-4EHA was observed at 326 ºC, 342
ºC, 311 ºC and 275 ºC, respectively. The thermal decomposition
of cNDI-1EHA was observed with a maximum decomposition
rate at 400 ºC (with mass loss of 100%) (FIg. 2a, red line). In the
case of cNDI-2EHA, the maximum rate decomposition at 410 ºC
(90%) was observed (FIg. 2b, blue line). TGA measurements
confirmed the decomposition maximum rate at 450 ºC (100%)
and 410 ºC (80%) for cNDI-3EHA (FIg. 2c, green line) and cNDI-
4EHA (FIg. 2d, black line), respectively. These TGA results
suggest that NDI materials cNDI-1EHA, cNDI-2EHA, cNDI-3EHA
and cNDI-4EHA are thermally stable and can be utilized at
higher annealing temperature for device fabrication.
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of absorption peaks in thin-films of cNDI-1EHA, cNDI-2EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA are summaVriiezweAdrtiicnleTOanblinlee
cNDI-3EHA and cNDI-4EHAis attributed to the strong 1. As shown in FIg. 4a, cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and
DOI: 10.1039/D0NJ05045H
intermolecular interactions and conformational adjustment of cNDI-4EHA exhibited multiple irreversible redox peaks as
the chromophores in thin-film formation. The Thin film spectra illustrated in FIg. 4a, 4b, 4c and 4d, respectively. The onset
were utilized for band gap calculations. The onset of absorption oxidation of cNDI-1EHA has one oxidation peak with an Eox
onset
onset
(λmax
in thin-film) for cNDI-1EHA, cNDI-2EHA, cNDI-3EHA potential at 0.80 V. NDI-2EHA displays one onset oxidative peak
and cNDI-4EHA at λ = 574 nm, 642 nm, 670 nm and 703 nm at 0.94 V. The onset oxidative peaks for NDI-3EHA and NDI-
determines the optical band gap as 2.16 eV, 1.93 eV, 1.85 eV 4EHA were appeared at 0.80 V and 0.90 V, respectively. The
and 1.76 eV, respectively. This suggests that increase in number HOMO energy level for the four chromophores cNDI-1EHA,
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of 2-ethyl-1-hexylamine substituent at NDI core exhibits longer cNDI-2EHA, cNDI-3EHA and cNDI-4EHA were estimated from
λmax
cNDI-4EHA and displays strong ICT transition, suggesting HOMO energy level of ferrocene to be -4.4 eV as shown in
onset
going from cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and the onset oxidation potential (Eoxonset) by assuming the absolute
significant decrease in optical band gap.
equation 1.
EHOMO = - (Eoxonset + 4.4) eV
(1)
The calculated HOMO energy level for cNDI-1EHA, cNDI-2EHA,
cNDI-3EHA and cNDI-4EHA are -5.20 eV, -5.34 eV, -5.20 eV and
-5.20 eV, respectively.
The LUMO energy levels of NDI-1EHA, NDI-2EHA, NDI-3EHA and
NDI-4EHA were estimated from equation 2 using onset
reduction values -1.00 V, -0.94 V, -1.06 V and -1.00 V,
respectively.
ELUMO = - (Eredonset + 4.4) eV
(2)
The LUMO energy level of cNDI-1EHA, cNDI-2EHA, cNDI-3EHA
and cNDI-4EHA are estimated to be -3.40 eV, -3.45 eV, -3.34 eV
and -3.42 eV, respectively. The LUMO energy level of cNDI-3EHA
(-3.34 eV) is higher than that of the cNDI-1EHA (-3.40 eV) cNDI-
2EHA (-3.45 eV) and cNDI-4EHA (-3.42 eV). The calculated band
gap for cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA are
1.80 eV, 1.90 eV, 1.86 eV and 1.80 eV, respectively. Such
chromophores are potential material for optoelectronic
applications.
Fig. 3 UV-vis absorption of cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA in
(a) DCM solution (1 × 10-4 M) and (b) in spin coated thin-films.
3.5. Electrochemical properties
The electrochemical properties of the cNDI-1EHA, cNDI-2EHA,
cNDI-3EHA and cNDI-4EHA were evaluated using cyclic
voltammetry (CV). The cyclic voltammetry properties were
recorded with saturated calomel electrode (SCE) reference
electrode in anhydrous dichloromethane with 0.1
M
tetrabutylammonium perchlorate (TBAP) electrolyte at a scan
rate of 100 mV/s under nitrogen atmosphere. As illustrated in
FIg. 4a, 4b, 4c and 4d and summarized in Table 1, the
electrochemical potentials were determined from the onset of
the oxidation. The electrochemical parameters of cNDI-1EHA,
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Table 1. Absorption (UV-vis) and electrochemical (CV) properties ofcNDI-1EHA, cNDI-
View Article Online
DOI: 10.1039/D0NJ05045H
2EHA, cNDI-3EHA and cNDI-4EHA.
5
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8
Molecular
Structure/Code
λmax in solution
(nm)
NDI-1EHA
NDI-2EHA
NDI-3EHA
NDI-4EHA
500
(shoulder),
528
418, 440,
470, 564
(shoulder)
606
578
(shoulder) ,
622
434
(shoulder),
460, 648
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λmax in Thin
Film (nm)
Thin film
530
574
598
607
670
642
703
642
λmaxonset (nm)
Eoptg (eV)
2.16
0.80
-1.00
-5.20
-3.40
1.93
0.94
-0.94
-5.34
-3.45
1.85
0.80
-1.06
-5.20
-3.34
1.76
0.90
-1.00
-5.30
-3.42
Eox
(V)
(V)
onset
Ered
onset
HOMO (eV)
LUMO (eV)
Eelg (ev)C
1.80
1.89
1.86
1.88
λmax: The absorption maxima from the UV–vis spectra in CHCl3 solution or in thin
film.
Eoptg : optical band gap determined from the absorption onset in thin film.
Eelg (ev) : electrochemical band gap determined from cyclic voltammetry.
3.6. Computational study
To investigate the computational UV-vis and electronic
properties of the compounds cNDI-1EHA, cNDI-2EHA, cNDI-
3EHA and cNDI-4EHA, density functional theory (DFT)
calculations were used. The results of the calculations reported
in this work have been obtained using the Gaussian 09ab
initio/DFT quantum chemical simulation package.55The
geometry optimization of molecules in the series cNDI-1EHA,
cNDI-2EHA, cNDI-3EHA and cNDI-4EHA have been carried out at
B3LYP/6-31G* level.In order to confirm the minima, frequency
calculations also have been carried out at the same level.
Further the geometries of cNDI-1EHA, cNDI-2EHA, cNDI-3EHA
and cNDI-4EHA obtained at B3LYP/6-31G* level were subjected
to time-dependent density functional theory (TD-DFT) studies
using B3LYP/6-31G* level for charge transfer excitations. TD-
DFT results were analyzed by employing Gauss-Sum 2.2.5
program,56 TD-DFT results obtained are illustrated in FIg. S22
and summarized in Table S2. From the TD-DFT results it is seen
that absorption trend matches with the UV-vis absorption of
cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA in spin
coated thin-film form (FIg. 3b). The frontier molecular orbitals
(FMO) are generated by using Avogadro57,58and are shown in
FIg. 5. cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA
commonly showed fully delocalised HOMOs and LUMOs across
the NDI molecular backbone. As the number of -2ethylhexyl
chain substitution increased, the HOMO and LUMO energy
levels decreased, in agreement with the electrochemical CV
results. The calculated energy band gaps of cNDI-1EHA, cNDI-
2EHA, cNDI-3EHA and cNDI-4EHA are 2.939 eV, 2.445 eV, 2.505
eV and 2.282 eV, respectively. The energy band gap decreased
slightly from cNDI-1EHA (2.939 eV) to cNDI-4EHA (2.282 eV).
Whereas, the Eg cNDI-3EHA (2.505 eV) is slightly higher than
that of cNDI-2EHA 92.445 eV). This decrease in energy band gap
trend from cNDI-1EHA to cNDI-4EHA is similar to the results
Fig. 4 Cyclic voltammograms of (a) cNDI-1EHA; (b) cNDI-2EHA; (c) cNDI-3EHAand
(d) cNDI-4EHA and ferrocene (Fc); in dichloromethane(DCM)solutions containing
0.10 M Bu4NPF6 as supporting electrolyte and platinum as a working electrode
with saturated calomel electrode (SCE) is a reference electrode. Fc was used as
the internal reference; scan rates: 0.100 mV/s, at 20 °C.
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obtained from the absorption measurements (Table 1). But the
calculated energy band gap values differ from the Egopt. This
disagreement in energy band gap values were attributed to the
DFT calculation of isolated molecules in the gas phase, whereas
the UV-vis absorption characteristics were affected by
intermolecular interactions via π-π staking interactions in the
solid state
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Fig. 5 Frontier molecular orbitals ofcNDI-1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-
4EHA with energy in eV.
3.7. Scanning electron microscopy (SEM)
SEM study was performed to evaluate their morphological
properties in films before and after annealing. The SEM images
of cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA before
o
and after annealing (performed at 170 C for 30 min) (FIg. 6)
clearly shows difference in self-assembling behaviour. Sheet-
like assembled structures of micrometer size can be clearly
seen for all the three samples, due to interaction of aliphatic
long alkyl chains on both the diimide position as well as core-
substitutions. The SEM images after annealing show clear
difference in morphology. cNDI-3EHA attains more crystallinity
as compared to cNDI-1EHA and cNDI-2EHA show less packed
structures. cNDI-4EHA is more hydrophobic and highly packed
films due to excimer formation and strong π–π stacking. The
cNDI-3EHA molecule bearing two alkyl chains on diimide
position and three alkyl chains on core allow to arrange the
molecule in well-ordered arrangement. Thus, based on SEM
images, we obtained assembled in following ordered cNDI-
1EHA<cNDI-4EHA<cNDI-2EHA<cNDI-3EHA and comparable to
report of Wasielewski59 and Govindraju.60
Fig. 6 SEM images for cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA before
annealing (a, c, e and g); after annealing (performed at 170 oC for 30 min)(b, d, f
and h), respectively.
3.8. X-ray diffraction characteristics
To further investigate the crystalline nature, we obtained high
power X-ray diffraction (XRD) patterns for all the four cNDI-
1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA as casted thin film
on Si-wafer see ESI FIg.S23. It can be seen that all four molecules
showing broad peaks which is evident of the formation of
ordered but non-crystalline file. However, after annealing of the
film of four samples at performed at 170 oC for 30 min, showing
the peaks lamellar d-spacing thin film at 2.4° found to be 8.17Å
along with broad peak at 6.17 Å for cNDI-1EHA, 5.83 Å for cNDI-
2EHA and 4.62 Å for cNDI-4EHA with increasing 2θ values with
increase in substituted chain number cNDI-1EHA>cNDI-2EHA>
cNDI-4EHA. Interestingly these broad peak missing in the case
of cNDI-3EHA, suggesting that the thin film after annealing in
the case of cNDI-3EHA exhibit completely different properties.
Nevertheless, cNDI-1EHA, cNDI-2EHA and cNDI-4EHA also have
broad peaks at 17.52 nm, however, cNDI-3EHAshows very sharp
peaks 2θ > 7.2°. This XRD study also clearly supports our earlier
hypothesis from SEM (FIg. 5) images, that cNDI-3EHA is self-
assembled better crystalline in nature than that of other cNDI-
1EHA, cNDI-2EHA and cNDI-4EHA derivatives.
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As illustrated in FIg. 7, based on SEM images (Fig. 6e and g
and Fig. 6f and h) we presume the plausible molecular
arrangement of cNDI-3EHA and cNDI-4EHA as film cased and
after annealing 170 oC for 30 min.
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푉2
퐿3
View Article Online
DOI: 10.1039/D0NJ05045H
퐽 = 휇휖
8
Where J is the current density, L is the thickness of the organic
semiconductor layer, is the mobility of organic
semiconductor, ε is the permittivity of medium, and V is applied
µ
9
voltage.
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The dark log(J)-log(V) curves for NDI chromophores-based
electron only devices are illustrated in Fig. 9 and the electron
mobility data are summarized in Table 2 and Table S1. Slope (i)
and slope (ii) shows the Ohmic and SCLC regions respectively
(Fig. 9). The cNDI-1EHA, cNDI-2EHA, cNDI-3EHA and cNDI-4EHA
molecules in ITO/ZnO/NDIs (~100 nm)/Ag device exhibited
electron mobility as high as 1.14×10-6cm2/Vs,1.25×10-4 cm2/Vs,
2.69×10-4 cm2/Vs and 1.4×10-6 cm2/Vs, respectively (FIg. 8 and
Table 2). The electron mobility in case of NDI-2EHA and NDI-
3EHA are higher than that of NDI-1EHA and NDI-4EHA,
suggesting that the number and position of 2-ethyl-1-
hexylamine chain play important role. The electron mobility
trend not depends on number of chain length rather formation
of crystalline material after annealing that is in the order cNDI-
1EHA<cNDI-4EHA<cNDI-2EHA<cNDI-3EHA. The highest electron
mobility value was observed with cNDI-3EHA. From XRD data
(FIg. S23) and SEM (FIg. S24) images is clear that cNDI-3EHA
produces very good crystalline morphologies have better
electron mobility.
Fig. 7 Schematic presentation of cNDI-3EHA and cNDI-4EHA chromophores before
annealing assembled into random structures for both of the molecules, however,
after annealing, cNDI-3EHA produces crystalline assembly and cNDI-4EHA thin
film, respectively.
3.9. Charge transport properties
To examine the influence of number and position of 2-ethyl-1-
hexylamine chain on n-type semiconducting properties, we
evaluated the electron mobility of these NDIs. The electron-only
device (ITO/ZnO/NDIs/Al) based on cNDI-1EHA, cNDI-2EHA,
cNDI-3EHA and cNDI-4EHA were fabricated and electron
mobility was calculated. The electron mobility was determined
by using the most versatile space charge limited current (SCLC)
model for organic semiconductor materials.42,49,61 As can be
seen in Fig. 8a&b, the single carrier devices have been
fabricated by sandwiching the NDI layer between contacts of
different work functions so as to allow only one type of charge
carriers selectively due to band-edge mismatch. The potential
barrier at the interface of ZnO (7.4 eV) and ITO (4.8 eV) blocks
the hole injection from ITO to NDI layer and only electrons are
expected to flow.
(b)
(a)
Fig. 9 Electron mobility of (a) cNDI-1EHA, (b) cNDI-2EHA, (c) cNDI-3EHAand cNDI-
4EHA. The device architecture is ITO/ZnO/NDIs/Al. The red lines show slope for
ohmic (i) and SCLC regions (ii) respectively.
Fig. 8 Schematic representation of fabricated electron only device with energy
level diagram of corresponding layers.
At room temperature, the space charge limited current shows
quadratic dependency on voltage. The electron mobility of the
NDI materials were extracted from the Mott-Gurney Eq. (1).
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Table 2: Best optimized condition for electron mobility properties of cNDI-1EHA, cNDI-
2EHA, cNDI-3EHA and cNDI-4EHA.
View Article Online
DOI: 10.1039/D0NJ05045H
R
=
O
O
5
6
7
8
Sample
Code
Concentration Anneali
Device
Structure
e-
6.08 ± 1.13 ×10−5
4.50 ± 3.03 × 10−4
9.04 ± 5.25 × 10−8
1.28 ± 1.32 × 10−3
ITO/ZnO/
NDI
R
R
R
=
=
=
(Chlorobenze
ne)
ng
Temp.
mobility
O
O
(cm2/Vs)
R
N
O
O
O
O
O
O
62
derivatives
(5-10
9
µm)/Al
cNDI-1EHA
cNDI-2EHA
40 mg/mL
40 mg/mL
170°C
170°C
ITO/ZnO/ cNDI-
1EHA/Al
1.14x10-6
1.25x10-4
N
R
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OH
O
O
O
O
ITO/ZnO/ cNDI-
2EHA/Al
R
=
NH
cNDI-3EHA
cNDI-4EHA
40 mg/mL
40 mg/mL
170°C
170°C
ITO/ZnO/ cNDI-
3EHA/Al
2.69x10-4
1.4x10-6
R1
N
H
1.14 x 10-6
1.25 x 10-4
2.69 x 10-4
1.4 x 10-6
=
=
=
=
=
R2,R3,R4
R1,R2
H
ITO/ZnO/
NDI
ITO/ZnO/ cNDI-
4EHA/Al
N
H
This
work
O
O
N
N
O
O
R3
R4
R1
R2
R3,R4
derivative
(40
H
R1,R2,R3
N
H
mg/mL)/Al
R4
H
=
=
The electron mobility results obtained from this work is compared
with the literature report on the electron mobility performance of
naphthalene diimide based small molecules by SCLC method and
are summarized in Table 3. The results display the comparative
electron mobility performance in this work compared to the
literature report.
R1,R2,R3,R4
N
H
4. Conclusions
Table 3: Literature reports on the performance of NDI based small molecules for electron
mobility characteristics with SCLC method.
In conclusion, we have synthesized four naphthalenediimide
(NDI) derivatives through core-substitution with varying
number of 2-ethyl-hexylamine (EHA) substituents at different
positions and studied their optical, self-assembling, electronic
and charge transport properties. The absorption measurement
Structures
Electron Mobility
cm-1 V-1 s-1
1.8 × 10-3
Device
Structure
Refer
ence
H3C(H2C)14
reveals that the increase in number of 2-ethyl-1-hexylamine
substituent at NDI core showed longer λmax
ITO/ZnO/
NDI
O
N
O
onset
and displays
49
derivative
(200
strong ICT transition, resulting significant decrease in optical
band gap. Electrochemical analysis shows the low-lying LUMO
energy level as required for stable n-type OSCs. The SEM and
XRD analysis clearly illustrates thatcNDI-3EHA gives more
crystallinity than the other three NDI derivatives showing strong
-stacking and van der Walls interactions within the
aggregated stacks that play a major role in arrangement of
molecules in directional growth. Further, the electron mobility
of the materials has also been evaluated which is in the range
of 10-4 to 10-6 cm2/Vs, clearly indicate that number and position
of 2-ethyl-1-hexylamine chain play effective role in electron
transport due to ordered film formation. The excellent electrical
and optical properties of these materials make them a
promising n-type material for wide applications in various
semiconducting devices.
nm)/Al
O
N
O
(CH2)14CH3
4.17 × 0−3
2.16 × 0−3
R
=
ITO/ZnO/
NDI
R
N
O
O
O
R
=
42
derivatives
(200
O2N
nm)/Al
N
R
O
2.5 × 10−5
7.9 × 10−4
R
R
=
=
F
F
F
F
F
Conflicts of interest
“All authors declare there are no conflicts of interest”.
Acknowledgements
S.V.B. (IICT) is grateful for financial support from the DAE-BRNS
Project Code: 58/14/01/2020-BRNS/37047, Mumbai, India.
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2015, 17, 26545-26552.
IICT/Pubs./2020/191.S. V. B. (GU) acknowledges financial
support from the UGC-FRP programme. S.S.B. is grateful for
financial support from CSIR, New Delhi for SRF fellowship.
Dedicated to Prof. Jürgen-Hinrich Fuhrhop on the occasion of
his 80th Birthday
View Article Online
DOI: 10.1039/D0NJ05045H
31 W. Liu, D.B. Shaikh, P. S. Rao, R. S. Bhosale, A. A. Said, A. M. Mak,
Z. Wang, M. Zhao, W. Gao, B. Chen, Y. M. Lam, W. Fan, S. V. Bhosale,
S. V. Bhosale and Q. Zhang, Chem. Asian J., 2020, 15, 112-121.
32 D. B. Shaikh, A. Said, R. S. Bhosale, W. Chen, S.V. Bhosale, A. L.
Puyad, S. V. Bhosale and Q. Zhang, Asian J. Org. Chem., 2018, 7, 2294-
2301.
33 A. A. Said, S. M. Wagalgave, J. Xie, A. L. Puyad, W. Chen, Z. Wang, S.
V. Bhosale, S. V. Bhosale and Q. Zhang, J. Solid State Chem.,2019, 270,
51-57.
Notes and references
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H. Sirringhaus, Adv.Mater.,2014, 26, 1319-1335.
34 S. Peng, J. Miao, I. Murtaza, L. Zhao, Z. Hu, M. Liu, T. Yang, Y. Liang,
H. Meng and A. W. Huang, J. Mater. Chem. C, 2017, 5, 5949-5955.
35 J. Miao, Z. Hu, M. Liu, M. U. Ali, O. Goto, W. Lu, T. Yang, Y. Liang and H.
Meng, Org. Electron.,2018, 52, 200-205.
2
(a) P. F. Van Hutten, V. V. Krasnikov and G. Hadziioannou, Acc. Chem. Res.,
1999, 32, 257-265; (b) Y. Watanable, H. Sasabe, and J. Kido, Bull. Chem.
Soc. Jpn. 2019, 92, 716-728; (c) J.-H. Lee, C.-H. Chen, P.-H. Lee, H.-Y. Lin,
M.-k. Leung, T.-L. Chiu, and C.-F. Lin, J. Mater. Chem. C, 2019, 7, 5874—
5888
36 S. Naqvi, M.Kumar and R. Kumar, ACS Omega, 2019, 4, 19735-19745
and the references cited herein.
3
4
C. Brabec, U. Scherf and V. Dyakonov, Organic Photovoltaics: Materials,
Device Physics, and Manufacturing Technologies, 2nd ed.; Wiley:
Hoboken, NJ, 2016.
37 J. H. Oh, S.-L. Suraru, W.-Y. Lee, M. Könemann, H. W. Höffken, C.
Röger, R. Schmidt, Y. Chung, W.-C. Chen, F. Würthner and Z. Bao, Adv.
Funct. Mater., 2010, 20, 2148-2156.
J. E. Anthony, A. Facchetti, M. Heeney, S. R. Marder and X. Zhan, Adv.
Mater., 2010, 22, 3876-3892.
38 J. G. Laquindanum, H. E. Katz, A. Dodabalapur and A. J. Lovinger, J. Am.
Chem. Soc., 1996, 118, 11331-11332.
5
6
7
8
A. Facchetti, Mater. Today, 2007, 10, 28-37.
39 J. Chang, Q. Ye, W. K. Huang, J. Zhang, K. J. Chen and J. Wu, C. Chi
Org. Lett., 2012, 14, 2964-2967.
K.-J. Baeg, M. Caironi and Y.-Y. Noh, Adv. Mater., 2013, 25, 4210-4244.
C.-a. Di, F. Zhang and D. Zhu, Adv. Mater., 2013, 25, 313-330.
H. Li, W. Shi, J. Song, H.-J. Jang, J. Dailey, J. Yu and H. E. Katz, Chem.
Rev., 2019, 119, 3-35.
40
41
42
43
X. Chen, Y. Guo, L. Tan, G. Yang, Y. Li, G. Zhang, Z. Liu, W. Xu and D.
Zhang, J.Mater. Chem. C, 2013, 1, 1087-1092.
J. Chang, J. Shao, J. Zhang, J. Wu and C. Chi, RSC Adv., 2013, 3, 6775-
6778.
9
J.Zaumesil and H. Sirringhaus, Chem. Rev., 2007, 107, 1296-1323.
10 J. Zhang, J. Jin, H. Xu, Q. Zhang and W.Huang, J. Mater. Chem. C, 2018,
6, 3485 – 3498.
N. Kumari, S. Naqui, M. Ahuja, K. Bhardwaj and R. Kumar, J. Mater. Sci.:
Mater. Electron.,2020, 31, 4310–4322.
11 H. E. Katz, A. J. Lovinger, J. Johnson, C. Kloc, T. Siegrist, W. Li, Y. Lin
and A. Dodabalapur, Nature,2000, 404, 478-481.
12 C. R. Newman, C. D. Frisbie, D. A. S. Filho, J. L. Brédas, P. C. Ewbank
And K. R. Mann,Chem. Mater.,2004, 16, 4436-4451.
13 A. Maliakal, In Organic Field-Effect Transistors; Z. Bao, J. Locklin, CRC
Press: Boca Raton, FL, 2007; p 229.
A. Dey, A. Kalita and P. K. Iyer, ACS Appl. Mater. Interfaces,2014, 6,
12295-2301.
44
45
T. He, M. Stolte and F. Würthner, Adv. Mater.,2013, 25, 6951-6955.
X. Gao, C.-a. Di, Y. Hu, X. Yang, H. Fan, F. Zhnag, Y. Liu, H. Li and D.
Zhu, J. Am. Chem. Soc.,2010, 132, 3697-3699.
46
47
48
H. Yan, Z. Chen, Y. Zheng, C. Newman, J. R. Quinn, F. Dötz, M. Kastler
and A. Facchetti, Nature,2009, 457, 679-687.
14 Y. Shirota and H. Kageyama, Chem. Rev., 2007, 107, 953-1010.
15 C. Wang, H. DongW. Hu, Y. Liu and D. Zhu, Chem. Rev., 2012, 112,
2208-2267.
W.-Y. Lee, J. H. Oh, S.-L. Suraru, W.-C. Chen, F. Würthner and Z. Bao,
Adv. Funct. Mater.,2011, 21, 4173-4181.
16 B. A. Jones, A.Facchetti, M. R. Wasielewski and T. J. Marks, J. Am.
Chem. Soc., 2007, 129, 15259– 15278.
F. Zhang, Y. Hu, T. Schuettfort, C.-A. Di, X. Gao, C.R. McNeill, L.
Thmsen, S. C. B. Mannsfeld, W. Yuan, H. Sirringhaus and D. Zhu, J. Am.
Chem. Soc.,2013, 135, 2338-2349
17 K. Iijima, Y. L. Gal, T. Higashino, D. Lorcy and T. Mori, J. Mater. Chem. C,
2017, 5, 9121-9127.
49
50
N. Kumari, S. Naqui and R. Kumar, J. Mater. Sci., 2018, 53, 4046-4055.
(a) R. Fernando, F. S. Etheridge, E. Muller and Sauve, New J. Chem.
2015, 39, 2506-2514; (b) R. Fernando, Z. Mao and G. Sauvé, Org.
Electron.,2013, 14, 1683-1692; (c) G. Sauvé,Chem. Rec., 2019,19, 1-16.
X. Guo, F. S. Kim, M. J. Seger, S. A. Jenekhe andM. D. Watson, Chem.
Mater.,2012, 24, 1434–1442 and references cited herein.
Z. Ma, H. Geng, D. Wangand Z. Shuai, J. Mater. Chem. C,2016, 4,
4546-4555.
18 K. Iijima, Y. L. Gal, D. Lorcy and T. Mori, RSC Adv.,2018, 8, 18400-
18405.
19 S.Naqvi, N.Vasishtha, M.Kumar and R. Kumar, New J. Chem., 2019,
43, 15626--15635.
51
52
53
20 S. Naqvi, N. Gupta, N.Kumari, J. Garg, R. Kumar, New J. Chem., 2017,
41, 1933-1939.
21 Y. Wang, T. Hasegawa, H. Matsumoto, T. Mori and T. Michinobu, Adv.
Mater., 2018, 30, 1707164.
A. Welford, S. Maniam, E. Gann, X. Jiao, L. Thomsen and S. J. Langford,
C. R. McNeill, Org. Electron., 2019, 75, 105378.
22 T. Hasegawa, M. Ashizawa, K. Aoyagi, H. Masunaga, T. Hikima and H.
Matsumoto, Org. Lett., 2017, 19, 3275-3278.
54 (a) M. Sasikumar, Y.V. Suseela and T.Govindaraju, Asian J. Org.
Chem.,2013, 2, 779-785; (b) X. Gao, W. Qiu, X. Yang, Y. Liu, Y. Wang,
H. Zhnag, T. Qi, Y. Liu, K. Lu, C. Du, Z. Shuai, G. Yu, and D. Zhu,
Org. Lett., 2007, 9, 3917-3920
23 Y. Qiao, Y. Guo, C. Yu, F. Zhang, W. Xu, Y. Liu and D. Zhu, J. Am. Chem.
Soc., 2012, 134, 084-4087.
24 K. Iijima and T. Mori, Chem. Lett., 2017, 46, 357-359.
25 T. Lei, Y. Cao, Y. Fan, C.-J. Liu, S.-C. Yuan and J. Pei, J. Am.Chem.
Soc.,2011, 133, 6099-6101.
55
Gaussian 09, Revision C.01 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G.
E. Scuseria,M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B.
Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P.
Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada,
M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y.
Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta,
F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N.
Staroverov, T. Keith, R. Kobayashi, J. Normand, K. Raghavachari, A.
Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M.
Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J.
Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R.
Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G.
Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D.
26 R. Stalder, J. Mei, K. R. Graham, L. A. Estrada and J. R. Reynolds, Chem.
Mater.,2014, 26, 664-678.
27 D. Yoo, X. Luo, T. Hasegawa, M. Ashizawa, T. Kawamoto, H.
Masunaga, N. Ohta, H. Matsumoto, J. Mei and T. Mori, ACS Appl.
Electron. Mater.,2019, 1, 764-771.
28
X. Zhan, A. Facchetti, S. Barlow, T. J. Marks, M. A. Ratner, M. R.
Wasielewski and S. R. Marder, Adv. Mater., 2011, 23, 268-284.
29 G. C. Schmidt, D.Höft, K. Haase, A. C. Hübler, E. Karpov, R. Tkachov,
M. Stamm, A. Kiriy, F. Haidu, D. R. T. Zahn, H. Yan and A. Facchetti, J.
Mater. Chem. C, 2014, 2, 5149-5154
30 R. Pfattner, C. Rovira and M. Mas-Torrent, Phys. Chem. Chem. Phys.,
10 | J. Name., 2012, 00, 1-3
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ARTICLE
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Daniels, O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, and D. J.
View Article Online
DOI: 10.1039/D0NJ05045H
Fox, Gaussian, Inc., Wallingford CT, 2010.
56
57
58
N.M. O'Boyle, A.L. Tenderholt and K.M. Langner, J. Comp. Chem.,2008,
29, 839-845.
Avogadro: an open-source molecular builder and visualization tool.
Version 1.1.0. http://avogadro.openmolecules.net/
M. D. Hanwell, D. E. Curtis, D. C. Lonie, T. Vandermeersch, E. Zurek and
G. R. Hutchison, J. Cheminformatics, 2012, 4, 17.
M.R. Wasielewski, Acc. Chem. Res., 2009, 42, 1910–19201.
M.B. Avinash and T. Govindraju, Adv. Funct. Mater., 2011, 21, 3875–
3882.
59
60
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
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32
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43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
J. C. Blakesley, F. A. Castro, W. Kylberg, G. F.A. Dibb, C. Arantes, R.
Valaski, M. Cremona, J.S. Kim and J. -S. Kim, Org. Electron.,2014, 15,
1263-1272.
M. B. Avinash, K. Swathi, K. S. Narayan, and T. Govindaraju, ACS
Appl. Mater. Interfaces, 2016, 8, 8678−8685.
This journal is © The Royal Society of Chemistry 20xx
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