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Sonar, Prashant, Chang, Jingjing, Kim, Jae, Ong, Kok-Haw, Gann, Eliot,Manzhos, Sergei, Wu, Jishan, & McNeill, Christopher(2016)High-mobility ambipolar organic thin-film transistor processed from anonchlorinated solvent.ACS Applied Materials and Interfaces, 8(37), pp. 24325-24330.
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https://doi.org/10.1021/acsami.6b08075
1
High Mobility Ambipolar Organic Thin Film
Transistor Processed From a Non-Chlorinated
Solvent
Prashant Sonar,*a ,bJingjing Chang,* a,c,d Jae H. Kim,a,e Kok-Haw Ong,a Eliot Gann,f Sergei
Manzhos,g Jishan Wu,a,c Christopher R McNeillh
aInstitute of Materials Research and Engineering (IMRE), Agency for Science, Technology, and
Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03, Singapore 138634
bSchool of Chemistry, Physics and Mechanical Engineering, Queensland University of
Technology (QUT), 2 George Street, Brisbane, QLD-4001, Australia, E-mail:
cDepartment of Chemistry, National University of Singapore, 3 Science Drive 3, 117543,
Singapore
dWide Bandgap Semiconductor Technology Disciplines State Key Laboratory, School of
Microelectronics, Xidian University, Xi’an, 710071, China, E-mail: [email protected]
eAnglo-Chinese School, 121 Dover Road, Singapore 139650
fAustralian Synchrotron, 800 Blackburn Road, Clayton, VIC, 3168, Australia
2
gDepartment of Mechanical Engineering Faculty of Engineering, National University of
Singapore Block EA #07-08, 9 Engineering Drive 1, Singapore 117576
hDepartment of Materials Science and Engineering, Monash University, Wellington Road,
Clayton VIC, 3800, Australia
KEYWORDS: diketopyrrolopyrrole, difluorothiophene, polymer semiconductors, ambipolar
transistors, non-chlorinated solvent, balanced charge carrier mobilities
ABSTRACT: Polymer semiconductor PDPPF-DFT, which combines furan substituted
diketopyrrolopyrrole (DPP) and 3, 4-difluorothiophene based, has been designed and
synthesized. PDPPF-DFT polymer semiconductor thin film processed from non-chlorinated
hexane is used as an active layer in thin-film transistors. As a result, balanced hole and electron
mobilities of 0.26 cm2/Vs and 0.12 cm2/Vs are achieved for PDPPF-DFT. This is the first report
of using non-chlorinated hexane solvent for fabricating high performance ambipolar thin film
transistor devices.
In the scientific community, the ambipolar organic thin film transistors (OTFT) gained
significant attention in past few years due to their use in single-component OTFT devices for
complementary metal oxide semiconductor (CMOS)-like circuits.1-7 Such circuits can
significantly reduce the complexity of the patterning and fabrication processes. By using
ambipolar OTFTs, we have successfully demonstrated high gain inverters and flexible memory
devices with higher performance.8-10 In addition to the above applications, ambipolar OTFTs are
also potential candidates for light emitting transistor devices.11-12 Such light emitting transistors
are promising components for the future lighting applications. For all the mentioned applications,
3
it is extremely important for an ambipolar semiconductor material with high yet comparable hole
and electron balanced charge carrier mobility. The balanced ambipolar charge transport
characteristics can be achieved by modulating the energy levels, of the HOMO (highest occupied
molecular orbital) and the LUMO (lowest unoccupied molecular orbital) of the polymer
semiconductors via the design of appropriate chemical functionalities in the conjugated
backbone. To fine-tune the energy levels of polymer semiconductors, a feasibly and commonly
used strategy is to combine alternating donor–acceptor (D–A) conjugated moieties in the
polymer backbone.13-14 The HOMO energy level of a polymer semiconductor is related to its
ionization potential and and the LUMO to the electron affinity; these are critical for the donor
and acceptor moieties, respectively. Many of the high performance ambipolar OTFTs reported
recently are based on polymer semiconductors that contain thiophene substituted
diketopyrrolopyrrole copolymers, usually combined with strong acceptors.15-17 Furan, which is a
five-membered heterocycle, is also a promising candidate; however, this block has so far not
been effectively used for designing new ambipolar OTFTs. Furan is an important biomass
precursor and can be considered a “green” electronic material.18-19 Furan substituted
diketopyrrolopyrrole (DPP) “3,6-Di(furan-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione” (DBF)
is a favorable conjugated fused aromatic heterocyclic moiety for ambipolar OTFTs, and recently
our group successfully demonstrated DBF based copolymers for high performance ambipolar
OTFT devices.20-21
Till date, almost all the high performing OTFTs were fabricated using chlorinated solvents
such as chloroform, chlorobenzene, dichlorobenzene, which can cause significant environmental
damage during manufacturing, use and disposal.22-23 For large scale flexible OTFTs and roll to
roll printable organic electronic devices, the use of toxic chlorinated solvents can be a serious
4
issue due to the additional environmental costs at the mass-production stage. However, non-
chlorinated solvents are still less used in organic electronics device processing, as most of the
polymer semiconductors reported to date have poor solubility in such solvents. The replacement
of the heterocylic thiophene moiety with furan of DPP core is a good molecular design approach
to enhance solubility of such organic semiconductors in non-chlorinated solvents. Such tuning
could allow environmentally benign processing and will also provide an opportunity to make
biodegradable electronic materials and devices due to incorporation of “green” furan building
blocks. Until now, there are a limited number of approaches to fabricate devices using non-
chlorinated solvents in the field of printable organic electronic devices.24-25 Thus, it is necessary
to explore the possibility of using non-chlorinated solvents such as hexane in such device
fabrication or printing technology. In this context, there is an emerging significance of
developing both green electronic materials and green processing technologies. Environment-
friendly furan with DPP can become an ideal building block for constructing low band gap
donor-acceptor semiconducting polymers. There are, however, few reports on these class of
materials compared to its analogous thiophene substituted DPP.
In this research work, we are reporting the molecular design, synthesis and characterization of
an innovative solution-processable alternating copolymer PDPPF-DFT using furan-substituted
DPP (electron accepting DBF block) and novel electron accepting 3, 4-difluoro thiophene (DFT)
moieties. We use this polymer as an active channel semiconductor in ambipolar OTFTs using
hexane as the processing solvent. The substitution of two electron withdrawing fluorine atoms on
the thiophene makes DFT to be a promising novel electron accepting building block.
Incorporation of such block with fused furan flanked DPP in the conjugated backbone of
polymers could enhance π-π stacking through hydrogen bonding between electronegative
5
fluorine atoms and hydrogen atoms on the neighboring furan DPP. Additionally, fluorination of
the backbone of the polymer could diminish the HOMO energy level, resulting in improved
stability and can promote the intra-molecular interaction of S-F and H-F for better packing.26-27
Furthermore, higher thermal stability can be achieved by incorporating fluorine in the backbone
of the conjugated chain. A strong donor-acceptor interaction between DBF and DFT may
enhance the degree of planarity, which may facilitate charge carrier transport. For ambipolar
OTFT operation, DFB and DFT units can tune the HOMO and LUMO energies of the polymer
via intermixing of frontier molecular orbitals, leading to optimal energy levels for hole/electron
conductance.
Scheme 1. (a) Synthesis of donor-acceptor PDPPF-DFT copolymers and (b) isosurfaces of
HOMO and LUMO orbitals of PDPPF-DFT polymer repeating unit. Atom colors: C – brown, O
– red, N – blue, S – yellow, H – pink, F – violet.
6
The synthesis route to make the polymer semiconductor PDPPF-DFT is outlined in Scheme 1.
The analysis of frontier orbitals shows significant LUMO amplitude on the fluorine atoms in the
fluorinated furan, reflecting the electron withdrawing nature of F (Scheme 1b). Firstly, the
compound 3,6-bis-(5-bromo- furan-2-yl)-N,N’-bis(2-octyldodecyl)-1,4-dioxo-pyrrolo[3,4-
c]pyrrole (1) was easily synthesized by using furan flanked DPP core 3,6-di(furan-2-
yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione followed by alkylation and bromination reactions.
Another monomer (3,4-difluorothiophene-2,5-diyl)bis(trimethylstannane) (2) was synthesized
via lithiation reaction using n-butyl lithium followed by addition of trimethyl tin chloride and the
starting compound 3,4-difluorothiophene using an earlier reported procedure.28-29 Reactions of
compounds 1 and 2 via Stille coupling polymerization gave the polymer poly{3,6-difuran-2-yl-
2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt- 3,4-difluoro thiophene} (PDPPF-
DFT) as a crude polymeric material (Scheme 1). PDPPF-DFT crude polymer was then purified
by sequential Sohxlet extraction using methanol and acetone separately in order to remove
impurities such as catalysts and oligomers. A good solubility of the polymer in the non-
chlorinated hexane solvent is due to the long branched octyldodecyl chains substituted on the
DPP core and use of short thiophene comonomer building blocks. Such molecular engineering
(using long branched alkyl chain substitution and appropriate comonomer) strategy is helpful for
enhancing solubility in non-chlorinated solvents such as hexane.
The thermal properties of PDPPF-DFT were studied by the differential scanning calorimetry
(DSC) and thermogravimetric analysis (TGA) techniques (See Supporting Information S3). The
second heating scan of the DSC measurement revealed an endothermic peak at 202 ºC, whereas
upon cooling, an exothermic peak was revealed at 129 ºC. The lower melting temperature of
PDPPF-DFT polymer is attributed to the longer alkyl chain substituted on the DPP moiety. A
7
decomposition temperature of 360 °C was determined by performing TGA under a nitrogen
atmosphere, indicating that the polymer has high thermal stability.
Figure 1. (a) UV-vis absorption spectra of PDPPF-DFT in solution (chloroform) and in solid
state (thin film processed from chloroform solution). (b) Photoelectron spectroscopy (PESA)
analysis of PDPP-DFT thin films on glass in air.
The optical properties of PDPPF-DFT polymer were studied by UV-Vis absorption
spectroscopy both in chloroform solution and thin film deposited on a glass substrate. The
solution measurements show the maximum absorption peak (λmax) at 800 nm, with an almost
identical λmax in the thin film spectrum (Figure 1a). The optical band gap of PDPPF-DFT was
4.6 4.8 5.0 5.2 5.4 5.6
2
4
6
8
10
12
14
16
18
Yie
ld 1/
2 [co
unts
1/2
]
Energy [eV]
HOMO = 5.40eV
300 450 600 750 9000.0
0.5
1.0
Inte
nsity
(a.
u)
Wavelength (nm)
Solution Thin Film
(a)
(b)
8
calculated from the solid state UV-Vis absorption spectrum by calculating absorption cut-off
value. The absorption cut-off was found to be at ~850 nm which gives optical band gap of 1.45
eV. Theoretical absorption spectrum calculations were performed on the repeating unit monomer
and dimer (See Figure S4 and S5) and the peak maximum of the dimer of 768 nm is close to the
measured peak maximum shown in Figure 1. One expects the peak to shift slightly to the red for
higher degree of polymerization (cf. monomer). In order to estimate the HOMO and LUMO
energy levels of PDPPF-DFT, first the HOMO value was estimated from the photoelectron
spectroscopy in air (PESA) measurements on the spin coated thin film of PDPPF-DFT on glass.
As shown in Figure 1b, the intersection of photoelectron yield ratio and UV photon energy gave
the onset energy level value and the HOMO value was calculated around -5.40 eV. The obtained
HOMO value of the polymer PDPPF-DFT (-5.40 eV) is lower than earlier reported ambipolar
polymer PDPPHD-T3 (-5.32 eV) due to electron withdrawing two fluorine atom substituted on
thiophene comonomer.30 The LUMO value could be obtained by calculating the difference
between solid-state optical band gap and HOMO value. The LUMO value was found to be -4.03
eV. From both HOMO and LUMO values, it can be seen that the energy levels of PDPPF-DFT
are just appropriate for hole and electron injection if gold can be used as an electrode in OTFT
devices.
In order to explore the consequence of fluorine substitution on the energy level stabilization,
frontier orbitals for fluorinated repeating unit and non-fluorinated repeating unit were computed
with DFT (density functional theory). HOMO and LUMO for the fluorinated monomer are
shown in Scheme 1 and are compared with non-fluorinated in Figure S6. From these theoretical
HOMO-LUMO orbitals, it can be seen that following the fluorination of the thiophene units,
both HOMO and LUMO are somewhat delocalized on the electron-withdrawing fluorine atom,
9
which corresponds to the stabilization of these orbitals. The computed frontier orbital energies
are listed in Table S1. Both HOMO and LUMO energies are stabilized by about 0.2 eV in
comparison with the non-fluorinated analogues, reflecting the electron withdrawing nature of F.
The band gap is little affected by fluorination. The extent of stabilization was similar in
monomer and dimer calculations and in DFT (abridged side chains shown in Scheme 1) and
DFTB (full side chains shown in Figure S5) and therefore likely holds for a polymer. The
differences between the experimentally estimated HOMO and LUMO and those in Table S1 are
attributable to the finite size of the model, aggregate state, and the approximations made.
Figure 2. (a) 2-D XRD diffractogram (inset: 2-D XRD images) with the incident X-ray parallel
to the PDPPF-DFT copolymer flakes, (b) 2D GIWAXS patterns of (left image) as cast and
(right image) 250°C annealed thin films of PDPPF-DFT.
10
In order to confirm stacking behavior of polymer chains, we used two-dimensional X-ray
diffractometry (2-D XRD) on polymer flakes. 2D-XRD analysis was performed on the PDPPF-
DFT via X-ray parallel and perpendicular modes to the polymer films. Such measurement can
provide important information about the molecular packing and solid state ordering. As
presented in Figure 2a, when the polymer films are parallel to X-ray, the primary diffraction
peak was measured at 2θ = 5.79° which corresponds to the interspacing distance of 15.27 Å,
whereas the wide-ranging peak positioned from 2θ = 16° to 24° demonstrates that PDPPF-DFT
film is weak crystalline. The interlayer distance derived from the broad peak at 2θ = 20.89° is
4.24 Å. In order to get a clear understanding of nanostructuring and self-assembly using few tens
of nanometer (40-50 nm) thin film of polymer directly deposited on Si/SiO2 substrates and
orientation distribution of the semiconducting polymer chains, Grazing Incidence Wide Angle X-
ray Scattering (GIWAXS) measurements were performed. The GIWAXS results (Figure 2b)
show an apparent lack of order in the as-cast film and only weak alkyl stacking and π-stacking
observed in the annealed film. The GIWAXS results provide an alkyl stacking distance of 19 1
Å which is larger than that recorded from the bulk XRD measurement suggesting a different
packing geometry in thin film. The polymer crystallites that exist in the annealed film do not
show a preference for edge-on or face-on with a value of Herman’s orientation parameter of S =
-0.01 +/- 0.01 for the annealed sample (S may vary from a value of S = 1.0 for perfectly edge-on
stacking to which runs from perfectly face-on at S = -0.5 for perfect face-on stacking; a value of
S = 0 shows no preferential orientation). To support this observation, PDPPF-DFT thin films
deposited directly to the octadecyltrichlorosilane (OTS) treated SiO2 (OTS-SiO2) substrates were
also measured using conventional XRD [Figure S7 (b)].
11
Figure 3. Transfer (a-b) and output (c-d) characteristic of a PDPPF-DFT based ambipolar
OTFT on OTS-SiO2 substrate with 150 °C annealing. The transfer curves of hole and electron
operation (channel length = 60 µm; channel width = 1 mm).
The field effect transistor characteristics using PDPPF-DFT as the active layer were
evaluated. The transistor devices adopt a bottom-gate, top-contact configuration. The device
fabrication is similar to the procedure reported previously.21 The PDPPF-DFT polymer thin film
(~40 nm) on OTS-SiO2 surface was obtained by spin-coating the hexane or chloroform solution
(6 mg/mL). The OTFT devices showed ambipolar behavior and from the saturation regime of the
transfer curves, the charge carrier mobilities could be obtained. Figure 3 and S8 show the
transfer and output characteristics, and Table S2 (see Supporting Information) summarizes the
device performance. Hole and electron mobilities of around 0.10 cm2/Vs and 0.013 cm2/Vs were
achieved for 100 °C annealed thin film. With 150 °C annealing, the hole and electron mobility
-80 -60 -40 -20 010-9
10-8
10-7
10-6
10-5
10-4
10-3
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|I DS
| (A
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VDS = -80 V
0 20 40 60 8010-8
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|I DS
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0 -20 -40 -60 -800
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VGS: 0V to -80V
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(A
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(a) (b)
(c) (d)
12
improves to 0.26 cm2/Vs and 0.12 cm2/Vs which is a very balanced high hole/electron mobility
for such a low annealing temperature. With 200 °C annealing, the hole mobility was further
improved to 0.30 cm2/Vs but electron mobility is reduced to 0.023 cm2/Vs. Figure 3 shows the
transfer and output characteristics of PDPPF-DFT based OTFTs annealed at 150 °C. The
transfer curves clearly show typical ambipolar V shaped behavior. The transistor showed slightly
bias stress effect in the saturation regime of output characteristics in the electron enhancement
mode due to charge trapping from dielectric surface and/or bulk materials (impurities or solvent
residues). The current on/off ratio (Ion/Ioff) of ~103-104 is calculated for all of the devices. In
addition to the hexane fraction, we also used the chloroform soluble fraction for fabricating
OTFT devices and a similar level of performance was obtained (see Table S2 in Supporting
Information). This is the first time that such high performance ambipolar OTFT devices
comparable with conventional halogenated solvent processed devices have been fabricated using
hexane.
Figure 4. AFM height (a-c) and phase (d-f) images of PDPPF-DFT thin films on OTS-SiO2
substrates annealed at 100°C, 150°C, and 200°C.
13
An atomic force microscopy (AFM) study was performed in order to correlate the effect of
thermal annealing on the device performance and to differentiate the morphological changes of
the thin films of PDPPF-DFT. The height and phase AFM images of the polymer thin films are
shown in Figure 4 and S9, and it is found that the polymer thin film with 100 °C annealing
exhibits less organized thin film morphology due to its amorphous nature. This is consistent with
the XRD results where no obvious diffraction peaks could be observed [Figure S7 (b)]. The thin
film microstructure becomes slightly more organized and the surface roughness decreases from
1.7 nm to 0.9 nm when the annealing temperature increased. The annealing process further
reduces the solvent residue related traps and hence improves the thin film mobility. When
annealing temperature increases to 200 °C, the thin films become discontinuous due to dewetting
problem caused by the melting and reorganization of polymer chains on OTS-SiO2 dielectric,
and this has been also observed and well supported during the DSC analysis of polymer. DSC
data clearly indicate the phase transition occurring around 200 °C, and this may be the reason for
the electron mobility decrease in the OTFT devices.
In summary, with the incorporation of innovative 3, 4-difluoro thiopehene and furan
substituted DPP blocks, the resulting solution processable polymer PDPPF-DFT has been
synthesized via Stille coupling. Ambipolar OTFT using PDPPF-DFT as an active channel
semiconductor has shown higher and balanced hole/electron mobility of 0.26 cm2/Vs and 0.12
cm2/Vs, respectively. We have also demonstrated that by using a non-chlorinated hexane solvent,
we can achieve comparable or higher hole/electron mobilities in ambipolar transistor devices.
Such a green processing solvent and utilization of a green electronic building block furan is a
promising approach to fabricate user-friendly printed electronic devices.
14
ASSOCIATED CONTENT
Supporting Information.
GPC elution curves, DSC and TGA thermograms, theoretical modelling details, XRD supporting
data, OTFT and AFM data of PDPPF-DFT. This material is available free of charge via the
Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: [email protected].
*E-mail: [email protected].
Author Contributions
The manuscript was written through contributions of all authors. All authors have given approval
to the final version of the manuscript.
ACKNOWLEDGMENTS
The authors thank the Institute of Materials Research and Engineering (IMRE), Agency for
Science, Technology and Research (A*STAR) and the “Printable high performance
semiconducting materials for OPVs and OTFTs” for financial support. P. S. is thankful to the
CRC for Polymers at Queensland University of Technology (QUT) for equipment support. We
are thankful to John Colwell (QUT) for the help in GPC measurement and Hong Duc Pham
(QUT) for DSC and TGA measurement. We are also thankful to Mr. Poh Chong Lim (IMRE) for
his help in 2-D XRD of the polymer. C. R. M. similarly thanks the ARC for research support
15
(DP130102616). J. W. acknowledges financial support from IMRE core funding (IMRE/13-
1C0205). This research was undertaken in part on the SAXS/WAXS beamline at the Australian
Synchrotron, Victoria, Australia.
REFERENCES
(1) Sonar, P.; Singh, S. P.; Li, Y.; Soh, M. S.; Dodabalapur, A. A Low-Bandgap
Diketopyrrolopyrrole-Benzothiadiazole-Based Copolymer for High-Mobility Ambipolar Organic
Thin-Film Transistors. Adv. Mater. 2010, 22, 5409–5413.
(2) Nielsen, C. B.; Turbiez, M.; McCulloch, I. Recent Advances in the Development of
Semiconducting DPP-Containing Polymers for Transistor Applications. Adv. Mater. 2013, 25,
1859–1880.
(3) Torricelli, F.; Ghittorelli, M.; Smits, E. C. P.; Roelofs, C. W. S.; Janssen, R. A. J.; Gelinck,
G. H.; Kovács-Vajna, Z. M.; Cantatore, E. Ambipolar Organic Tri-Gate Transistor for Low-
Power Complementary Electronics. Adv. Mater. 2016, 28, 284–290.
(4) Sonar, P.; Chang, J.; Shi, Z.; Wu, J.; Li, J. Thiophene–tetrafluorophenyl–thiophene: A
Promising Building Block for Ambipolar Organic Field Effect Transistors. J. Mater. Chem. C
2015, 3, 2080–2085.
(5) Kanimozhi, C.; Yaacobi-Gross, N.; Chou, K. W.; Amassian, A.; Anthopoulos, T. D.; Patil,
S. Diketopyrrolopyrrole-Diketopyrrolopyrrole-Based Conjugated Copolymer for High-Mobility
Organic Field-Effect Transistors. J. Am. Chem. Soc. 2012, 134, 16532–16535.
16
(6) Sonar, P.; Foong, T. R. B.; Singh, S. P.; Li, Y.; Dodabalapur, A. A Furan-Containing
Conjugated Polymer for High Mobility Ambipolar Organic Thin Film Transistors. Chem.
Commun. 2012, 48, 8383.
(7) Chen, Z.; Lemke, H.; Albert-Seifried, S.; Caironi, M.; Nielsen, M. M.; Heeney, M.; Zhang,
W.; McCulloch, I.; Sirringhaus, H. High Mobility Ambipolar Charge Transport in
Polyselenophene Conjugated Polymers. Adv. Mater. 2010, 22, 2371–2375.
(8) Gentili, D.; Sonar, P.; Liscio, F.; Cramer, T.; Ferlauto, L.; Leonardi, F.; Milita, S.;
Dodabalapur, A.; Cavallini, M. Logic-Gate Devices Based on Printed Polymer Semiconducting
Nanostripes. Nano Lett. 2013, 13, 3643–3647.
(9) Zhou, Y.; Han, S.; Sonar, P.; Roy, V. A. L. Nonvolatile Multilevel Data Storage Memory
Device from Controlled Ambipolar Charge Trapping Mechanism. Sci. Rep. 2013, 3, 2319.
(10) Chen, H.; Guo, Y.; Mao, Z.; Yu, G.; Huang, J.; Zhao, Y.; Liu, Y. Naphthalenediimide-
Based Copolymers Incorporating Vinyl-Linkages for High-Performance Ambipolar Field-Effect
Transistors and Complementary-like Inverters under Air. Chem. Mater. 2013, 25, 3589–3596.
(11) Bürgi, L.; Turbiez, M.; Pfeiffer, R.; Bienewald, F.; Kirner, H.-J.; Winnewisser, C. High-
Mobility Ambipolar Near-Infrared Light-Emitting Polymer Field-Effect Transistors. Adv. Mater.
2008, 20, 2217–2224.
(12) Gwinner, M. C.; Kabra, D.; Roberts, M.; Brenner, T. J. K.; Wallikewitz, B. H.; McNeill,
C. R.; Friend, R. H.; Sirringhaus, H. Highly Efficient Single-Layer Polymer Ambipolar Light-
Emitting Field-Effect Transistors. Adv. Mater. 2012, 24, 2728–2734.
17
(13) Guo, X.; Baumgarten, M.; Mullen, K. Designing Pi-Conjugated Polymers for Organic
Electronics. Prog. Polym. Sci. 2013, 38, 1832–1908.
(14) Pron, A.; Leclerc, M. Imide/amide Based π-Conjugated Polymers for Organic Electronics.
Prog. Polym. Sci. 2013, 38, 1815–1831.
(15) Li, Y.; Sonar, P.; Murphy, L.; Hong, W. High Mobility Diketopyrrolopyrrole (DPP)-
Based Organic Semiconductor Materials for Organic Thin Film Transistors and Photovoltaics.
Energy Environ. Sci. 2013, 6, 1684.
(16) Mohebbi, A. R.; Yuen, J.; Fan, J.; Munoz, C.; Wang, M. F.; Shirazi, R. S.; Seifter, J.;
Wudl, F. Emeraldicene as an Acceptor Moiety: Balanced-Mobility, Ambipolar, Organic Thin-
Film Transistors. Adv. Mater. 2011, 23, 4644–4648.
(17) Chang, J.; Lin, Z.; Li, J.; Lim, S. L.; Wang, F.; Li, G.; Zhang, J.; Wu, J. Enhanced
Polymer Thin Film Transistor Performance by Carefully Controlling the Solution Self-Assembly
and Film Alignment with Slot Die Coating. Adv. Electron. Mater. 2015, 1, 1500036.
(18) Gidron, O.; Dadvand, A.; Sheynin, Y.; Bendikov, M.; Perepichka, D. F. Towards “green”
electronic Materials. α-Oligofurans as Semiconductors. Chem. Commun. 2011, 47, 1976–1978.
(19) Gidron, O.; Diskin-Posner, Y.; Bendikov, M. α-Oligofurans. J. Am. Chem. Soc. 2010, 132,
2148–2150.
(20) Woo, C. H.; Beaujuge, P. M.; Holcombe, T. W.; Lee, O. P.; Frechet, J. M. J.
Incorporation of Furan into Low Band-Gap Polymers for Efficient Solar Cells. J. Am. Chem. Soc
2010, 132, 15547–15549.
18
(21) Sonar, P.; Chang, J.; Shi, Z.; Gann, E.; Li, J.; Wu, J.; McNeill, C. R. Hole Mobility of
3.56 cm2V−1s−1 Accomplished Using More Extended Dithienothiophene with Furan Flanked
Diketopyrrolopyrrole Polymer. J. Mater. Chem. C 2015, 3, 9299–9305.
(22) Kang, I.; Yun, H. J.; Chung, D. S.; Kwon, S. K.; Kim, Y. H. Record High Hole Mobility
in Polymer Semiconductors via Side-Chain Engineering. J. Am. Chem. Soc. 2013, 135, 14896–
14899.
(23) Yi, Z.; Wang, S.; Liu, Y. Design of High-Mobility Diketopyrrolopyrrole-Based π-
Conjugated Copolymers for Organic Thin-Film Transistors. Adv. Mater. 2015, 27, 3589–3606.
(24) Yun, H.-J.; Lee, G. B.; Chung, D. S.; Kim, Y.-H.; Kwon, S.-K. Novel
Diketopyrroloppyrrole Random Copolymers: High Charge-Carrier Mobility From
Environmentally Benign Processing. Adv. Mater. 2014, 26, 6612–6616.
(25) Chang, J.; Chi, C.; Zhang, J.; Wu, J. Controlled Growth of Large-Area High-Performance
Small-Molecule Organic Single-Crystalline Transistors by Slot-Die Coating Using a Mixed
Solvent System. Adv. Mater. 2013, 25, 6442–6447.
(26) Kim, H. G.; Kang, B.; Ko, H.; Lee, J.; Shin, J.; Cho, K. Synthetic Tailoring of Solid-State
Order in Diketopyrrolopyrrole-Based Copolymers via Intramolecular Noncovalent Interactions.
Chem. Mater. 2015, 27, 829–838.
(27) Shewmon, N. T.; Watkins, D. L.; Galindo, J. F.; Zerdan, R. B.; Chen, J.; Keum, J.;
Roitberg, A. E.; Xue, J.; Castellano, R. K. Enhancement in Organic Photovoltaic Efficiency
through the Synergistic Interplay of Molecular Donor Hydrogen Bonding and π-Stacking. Adv.
Funct. Mater. 2015, 25, 5166–5177.
19
(28) Homyak, P.; Liu, Y.; Liu, F.; Russel, T. P.; Coughlin, E. B. Systematic Variation of
Fluorinated Diketopyrrolopyrrole Low Bandgap Conjugated Polymers: Synthesis by Direct
Arylation Polymerization and Characterization and Performance in Organic Photovoltaics and
Organic Field-Effect Transistors. Macromolecules 2015, 48, 6978–6986.
(29) Park, S.; Cho, J.; Ko, M. J.; Chung, D. S.; Son, H. J. Synthesis and Charge Transport
Properties of Conjugated Polymers Incorporating Difluorothiophene as a Building Block.
Macromolecules 2015, 48, 3883–3889.
(30) Li, Y.; Singh, S. P.; Sonar, P. A High Mobility P-Type DPP-thieno[3,2-b]thiophene
Copolymer for Organic Thin-Film Transistors. Adv. Mater. 2010, 22, 4862–4866.
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