Shear-Enhanced Stretchable Polymer Semiconducting Blends for Polymer-based Field-Effect Transistors

Qian-Yu Yan,Yu-Wei Shia,Dong-Yue Guo,Wen-Ya Lee 한국고분자학회 2020 Macromolecular Research Vol.28 No.7

Solution-sheared field-effect transistors based on the blend of the highmobility donor–acceptor conjugated copolymer poly(diketopyrrolo[3,4-c]pyrroleco- thieno[3,2-b]thiophene) (PDBT-co-TT) and the elastic polymer poly(styrene-butadienestyrene) (SBS) are demonstrated for stretchable electronics. In this study, PDBT-co- TT serves as a charge transport layer, and the insulating polymer SBS with double bonds is used for improving elasticity. Through combination with solution shearing, the phase separation and charge transport properties of the PDBT-co-TT/SBS blends can be manipulated. Compared with the spin-coated PDBT-co-TT/SBS blends showing lower charge mobilities (~10-3 cm2 V-1 s-1), the solution-sheared polymer-blend films with the PDBT-co-TT content of 20% maintain high mobility (>0.1cm2 V-1 s-1). The films with 60% PDBT-co-TT can even achieve mobility as high as 2 cm2 V-1 s-1, which is higher than the pristine conjugated polymer. Furthermore, as the SBS content increases, the dichroic ratios of the solution-sheared blends increase, indicating improved alignment of the conjugated polymer chains. The PDBT-co- TT/SBS blends exhibit great stretchability and high charge mobilities even under 100% strain due to their mesh-like morphology. Moreover, solution shearing not only improves polymer alignment but also controls surface morphology to enhance stretchability. This work reveals the importance of solution shearing in high-mobility stretchable polymer semiconductor blends.

Solution-based Sulfur-Polymer Coating on Nanofibrillar Films for Immobilization of Aqueous Mercury Ions

이재혁,이세영,김지희,자히드,한승희,홍석원,윤명한 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.1

Herein, we report the solution-based method for coating sulfur polymers on various substrate materials. First, sulfur polymers were synthesized by reacting elemental sulfur and 1,3-diisopropenylbenzene and dissolved in various organic solvents to search for solvents with good solubility. Next, the trend in film thickness of sulfur-polymer coating was systematically examined using the sulfur-polymer solutions in dichlorobenzene (DCB) and various materials with different surface energy. The nanofibrillar film made of the poly(vinyl alcohol) and poly(acrylic acid) (PVA-PAA) blend exhibited the most uniform/conformal deposition of sulfur polymer via dipping-coating, indicating that the DCB solution is most suitable for the well-controlled deposition of sulfur polymer on nanostructured materials with higher surface energy than 40 mN/m. Finally, the resultant sulfur polymer-coated nanofibrillar film showed high mercury ion uptake capacity (26 mg/g with 50 ppm Hg solution) even with a small amount of sulfur-based adsorbent (20 mg) loading on the film (40 mg). Our study suggests that the sulfur polymer solution can introduce the crucial properties of elemental sulfur on the surface of any conventional materials even with mechanical flexibility and nano/microscale structural complexity.

Enhanced gate-bias stress stability of organic field-effect transistors by introducing a fluorinated polymer in semiconductor/insulator ternary blends

Jeong, Yong Jin,Yun, Dong-Jin,Nam, Sooji,Jang, Jaeyoung Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.481 No.-

<P><B>Abstract</B></P> <P>Solution-processed polymer semiconductors are key materials in the fabrication of lightweight, low-cost, and flexible electronic devices without using the high-vacuum process. For practical applications, reliable device operations based on these materials are required. In this study, we propose a strategy to improve the operation stability of organic field-effect transistors (OFETs) using solution-processed polymer semiconductor/insulator blends as the active channel prepared by introducing a fluorinated insulating polymer in the blends. The semiconducting polymer forms nanowire networks in spin-coated ternary blend films, which serve as charge transport pathways in the insulating polymer matrix consisting of the fluorinated polymer and polystyrene. Owing to its high surface potential attributed to the strongly electron-withdrawing structure, the fluorinated polymer provides a large energy barrier for suppression of the hole trapping at the semiconductor/insulator interface. Consequently, OFETs based on the ternary blend films with an optimized polymer composition exhibit almost hysteresis-free transfer and output characteristics and superior electrical stabilities under sustained gate-bias stresses in both N<SUB>2</SUB> and air atmospheres. We believe that our study provides a practical route to the fabrication of OFETs based on polymer semiconductor/insulator blend systems with high operation stabilities.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A fluorinated polymer PFS was introduced in semiconductor/insulator ternary blends. </LI> <LI> P3HT formed nanowire networks in the blend films and acted as charge transport pathways. </LI> <LI> PFS induced a large energy barrier for suppression of the hole trapping at interfaces. </LI> <LI> The OFETs using the blend film as the active layer exhibited superior gate-bias stabilities. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Doping of donor-acceptor polymers with long side chains via solution mixing for advancing thermoelectric properties

Suh, Eui Hyun,Jeong, Yong Jin,Oh, Jong Gyu,Lee, Kyumin,Jung, Jaemin,Kang, Yong Soo,Jang, Jaeyoung Elsevier 2019 Nano energy Vol.58 No.-

<P><B>Abstract</B></P> <P>One-step doping of conjugated polymers by solution mixing is typically performed instead of sequential doping because of its simplicity. However, doped polymer solutions often exhibit poor solubility, and the presence of dopants in the produced films can disturb the molecular ordering of polymer structures. In this work, effective pairs of two donor-acceptor (D-A) type polymers and a molecular dopant characterized by high solution stability and good thermoelectric properties of the prepared thin films have been reported. The presence of long side chains in the polymer structures preserves their original solubilities and crystallinity in the solution and thin-film states, respectively, even at large amounts of added dopant (up to 38 mol%). Furthermore, the relatively shallow levels of the highest occupied molecular orbitals of the selected D-A polymers enable efficient charge transfer from the dopant species. Owing to their good charge transport properties, the doped D-A polymers exhibit outstanding thermoelectric properties with a maximum power factor of 31.5 μW m<SUP>−1</SUP> K<SUP>−2</SUP>, which is more than an order of magnitude higher than those of the control samples prepared from donor-only poly(3-hexylthiophene).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Doping of two donor-acceptor polymers (PCDTFBT and PCDTPT) is performed by simple one-step solution mixing. </LI> <LI> The long side chains of the polymers allow high solution stabilities of the polymer-dopant mixtures. </LI> <LI> The polymer films retain structural coherence even after doping with high dopant ratios up to 38 mol%. </LI> <LI> Owing to their good charge transport properties, the doped polymers exhibit high thermoelectric power factors up to 31.5 μW m<SUP>-1</SUP> K<SUP>−2</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Outstanding thermoelectric properties of two D-A polymers are demonstrated by molecular doping with F<SUB>4</SUB>TCNQ via a simple one-step solution mixing process. The long side chains preserve good solubilities of these materials in solution and preferential molecular ordering in thin films at dopant contents of up to 38 mol%. Efficient doping is ensured by their relatively shallow HOMO levels.</P> <P>[DISPLAY OMISSION]</P>

Polymer nanocomposites reinforced with multi-walled carbon nanotubes for semiconducting layers of high-voltage power cables

Jeong, Kwang-Un,Lim, Jee Young,Lee, Jong-Young,Kang, Seong Lak,Nah, Changwoon John Wiley Sons, Ltd. 2010 Polymer international Vol.59 No.1

<P>Polymer nanocomposites reinforced with multi-walled carbon nanotubes (MWCNTs) have been newly introduced for semiconducting layers of high-voltage electrical power cables. Homogeneity of the MWCNT-reinforced polymer nanocomposites was achieved by solution mixing, and their mechanical, thermal and electrical properties were investigated depending on the type of polymer. By changing the polymer matrix, the volume resistance of the MWCNT-reinforced polymer nanocomposites could be varied by more than four orders of magnitude. Through systematic experiments and analysis, two possible factors affecting the volume resistance were found. One is the degree of crystallinity of the polymer used and the other is the change of MWCNT morphology under strain. By increasing the degree of crystallinity above a certain level, the volume resistance linearly increased. The MWCNTs embedded in the nanocomposites gradually protruded through the surface on stretching the sample and reversibly returned back to the original positions at a relatively small strain (below 20%). Based on the criteria of tensile properties and volume resistance, a poly[ethylene-co-(ethyl acrylate)]/MWCNT nanocomposite was selected as the best candidate for the semiconducting layers of high-voltage electrical power cables. Copyright © 2009 Society of Chemical Industry</P> <B>Graphic Abstract</B> <P>Based on the criteria of tensile properties and volume resistance, poly[ethylene-co-(ethyl acrylate)] (EEA)/MWCNT nanocomposite was selected as the best candidate for a SCL of high electrical power cables. <img src='wiley_img/09598103-2010-59-1-PI2696-gra001.gif' alt='wiley_img/09598103-2010-59-1-PI2696-gra001'> </P>

Highly efficient solution-processed inverted polymer light emitting diodes with uniformly coated poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) layers on a hydrophobic emission layer using a dilution method

Park, Jongjang,Ha, Jaeheung,Seong, Narkhyeon,Lee, Seunghwan,Lee, Changhee,Yang, Hoichang,Hong, Yongtaek Elsevier 2018 THIN SOLID FILMS - Vol.660 No.-

<P><B>Abstract</B></P> <P>Inverted polymer light emitting diodes (PLEDs), where solution-processed multi-layers were sandwiched between indium tin oxide and thermally evaporated aluminum electrodes, were fabricated and their characteristics were measured. In order to achieve high performance in the inverted PLEDs, there is a need for additional functional layers such as a hole transport layer and hole injection layer (HIL) on an emission layer (EML), but formation of the solution-processed layers on the hydrophobic EML have been rarely reported due to the extremely poor wetting property of a poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) solution, which is a widely used HIL. Non-wetting phenomena such as the formation of islands or radiation patterns in PEDOT:PSS films on the EML caused by their poor wetting property have been completely removed using a dilution method. By diluting PEDOT:PSS solutions with ethanol and analyzing a wetting envelope, we found the optimized dilution condition (10:1) and fabricated highly efficient inverted PLEDs with the uniformly coated PEDOT:PSS HIL, showing a current efficiency of 9.73 cd/A at 1000 cd/m<SUP>2</SUP> and uniform light emission simultaneously.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Wetting analysis of poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) </LI> <LI> An ethanol dilution method to modulate wetting property of PEDOT:PSS </LI> <LI> Uniformly coated PEDOT:PSS layers on the hydrophobic emission layer </LI> <LI> Highly efficient and homogeneously emitting inverted polymer light emitting diodes. </LI> </UL> </P>

Micro and macro in the dynamics of dilute polymer solutions: Convergence of theory with experiment

J. Ravi Prakash 한국유변학회 2009 Korea-Australia rheology journal Vol.21 No.4

Recent developments in dilute polymer solution rheology are reviewed, and placed within the context of the general goals of predicting the complex flow of complex fluids. In particular, the interplay between the use of polymer kinetic theory and continuum mechanics to advance the microscopic and the macroscopic description, respectively, of dilute polymer solution rheology is delineated. The insight that can be gained into the origins of the high Weissenberg number problem through an analysis of the configurational changes undergone by a single molecule at various locations in the flow domain is discussed in the context of flow around a cylinder confined between flat plates. The significant role played by hydrodynamic interactions as the source of much of the richness of the observed rheological behaviour of dilute polymer solutions is highlighted, and the methods by which this phenomenon can be incorporated into a macroscopic description through the use of closure approximations and multiscale simulations is discussed.

Micro and macro in the dynamics of dilute polymer solutions: Convergence of theory with experiment

Prakash, J. Ravi The Korean Society of Rheology 2009 Korea-Australia rheology journal Vol.21 No.4

Recent developments in dilute polymer solution rheology are reviewed, and placed within the context of the general goals of predicting the complex flow of complex fluids. In particular, the interplay between the use of polymer kinetic theory and continuum mechanics to advance the microscopic and the macroscopic description, respectively, of dilute polymer solution rheology is delineated. The insight that can be gained into the origins of the high Weissenberg number problem through an analysis of the configurational changes undergone by a single molecule at various locations in the flow domain is discussed in the context of flow around a cylinder confined between flat plates. The significant role played by hydrodynamic interactions as the source of much of the richness of the observed rheological behaviour of dilute polymer solutions is highlighted, and the methods by which this phenomenon can be incorporated into a macroscopic description through the use of closure approximations and multi scale simulations is discussed.

Synthesis and characterization of poly(benzodithiophene) derivative for organic thin film transistors

Dang, Thi Tuyet Mai,Park, Sung-Jin,Park, Jong-Won,Chung, Dae-Sung,Park, Chan Eon,Kim, Yun-Hi,Kwon, Soon-Ki Wiley Subscription Services, Inc., A Wiley Company 2007 Journal of polymer science Part A, Polymer chemist Vol.45 No.22

<P>Poly{2,6-bis(3-dodecylthiophen-2-yl) benzo[1,2-b;4,5-b′]dithiophene} (PTBT) was synthesized, via oxidative polymerization by oxidative agent (FeCl<SUB>3</SUB>). The mole ratio of FeCl<SUB>3</SUB> and monomer (3.5:1), and keeping low temperature during the dropping of diluted catalyst were very important for the polymerization without crosslinking. The PTBT was confirmed by <SUP>1</SUP>H NMR, FTIR spectra, and elemental analysis. The PTBT has very good solubility in organic solvents such as chloroform, tetrahydrofuran, etc, and good thermal stability with T<SUB>g</SUB> of 164 °C. The PTBT shows UV-optical absorption at 406 nm and photoluminescence (PL) spectroscopy at 504 nm in a film. The highest occupied molecular orbital (HOMO) energy of the polymer is −5.71 eV by measuring cyclic voltammetry (CV). A solution-processed polymer thin film transistor device shows a mobility of 3 × 10<SUP>−5</SUP> – 8 × 10<SUP>−5</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, and an on/off current ratio of 10<SUP>4</SUP>. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5277–5284, 2007</P> <B>Graphic Abstract</B> <P>A new poly(benzodithiophene) derivative was designed, synthesized, and characterized. The polymer has very good solubility in organic solvents and good thermal stability with T<SUB>g</SUB> of 164 °C. The polymer shows UV-optical absorption at 406 nm, photoluminescence spectroscopy at 504 nm in a film, and oxidative potential with HOMO level of −5.71 eV. A solution-processed polymer thin film transistor device shows a mobility of 3 × 10<SUP>−5</SUP> to 8 × 10<SUP>−5</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, and an on/off current ratio of 10<SUP>4</SUP>.</P><P> <img src='wiley_img/0887624X-2007-45-22-POLA22272-gra001.gif' alt='wiley_img/0887624X-2007-45-22-POLA22272-gra001'> </P>

Vortex dynamics at the junction of Y-shaped microchannels in dilute polymer solutions

박용민,홍선옥,이평천,김주민 한국유변학회 2019 Korea-Australia rheology journal Vol.31 No.4

Understanding the vortex dynamics in polymer solutions is one of keys for the flow control in a wide range of polymer-related material processing applications. Vortex is generated due to the viscoelasticity of polymer solution, even if no vortex formation is expected under Newtonian flow conditions. In addition, the chaotic vortices generated in viscoelastic fluids have been recently exploited to mix different fluid streams in microfluidic devices. Herein, we investigated the vortex dynamics in dilute poly(ethylene oxide) solutions at the junction region of Y-shaped microchannels, which have been frequently used to mix two fluid streams. We report the formation of two types of vortices: A vortex at the stagnation point of the junction (center) and a lip vortex at the upstream of the sharp corner. Fluorescent microscopy revealed that the vortex dynamics was significantly affected by the angle between the two upstream channels, polymer concentration, and flow rate. We expect that this work will be useful for understanding the viscoelastic flow in microchannels and for the future design of microfluidic devices such as microfluidic mixers.