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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:

sonar.prashant@qut.edu.au

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: jjingchang@xidian.edu.cn

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

VG (V)

|I DS

| (A

)

0

2

4

6

8

10

|IDS

| 0.5 x 10

-3 (A0

.5)

VDS = -80 V

0 20 40 60 8010-8

10-7

10-6

10-5

10-4

10-3

VG (V)

|I DS

| (A

)

0

2

4

6

8

|IDS

| 0.5 x 10

-3 (A0

.5)

VDS = 80 V

0 -20 -40 -60 -800

-5

-10

-15

-20

-25

I DS

(A

)

VDS (V)

VGS: 0V to -80V

0 20 40 60 800

2

4

6

8

10

I DS

(A

)

VDS (V)

VGS: 0V to 80V

(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: sonar.prashant@qut.edu.au.

*E-mail: jjingchang@xidian.edu.cn.

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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