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Polyurethane triblock copolymer gate dielectrics for low-voltage organic thin-film transistors
김동규,김충익,Taeshik Earmme 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.71 No.-
Novel polyurethane triblock copolymers comprising polycaprolactone diol (PCL), 1,6-hexamethylene diisocyanate (HMDI), and polyethylene glycol (PEG) were synthesized for use as gate dielectric for organic thin-film transistors (OTFTs). Thin films of polyurethane gate dielectrics processed from solution exhibit excellent insulating properties (∼7 × 10−7 A/cm2 at 1 V) as well as large areal capacitance (170 nF/cm2) with film thickness of ∼50 nm. OTFTs are fabricated with representative n-channel organic semiconductor (N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide; PTCDI-C13) using the developed gate dielectrics, and the resulting devices show decent electrical performance with negligible hysteresis at low operating voltage of 1 V.
Effect of end-block chain length on rheological properties of ABA triblock copolymer hydrogels
Hyunjoon Jung,Taeshik Earmme,Soo-Hyung Choi 한국유변학회 2021 Korea-Australia rheology journal Vol.33 No.2
End-block length dependence of the hydrogel relaxation dynamics was investigated using PEO-based ABA triblock copolymer solutions in an aqueous solvent. Both ends of PEO were capped with hydrophobic poly(isopropyl glycidyl ether-co-ethyl glycidyl ether) exhibiting a lower critical solution temperature (LCST) behavior, resulting in the transition between sol and gel with temperature. Despite the nearly identical hydrophobicity of the end-blocks, the sol-to-gel transition temperature is found to be significantly dependent on the end-block length. Particularly, a small increment of the end-block length leads to significantly slower relaxation dynamics which is attributed to the thermodynamic barrier of end-block extraction. Hydrogels with an appropriate relaxation time show excellent injectability and self-healing ability, yet extremely slow relaxation dynamics result in brittle hydrogels. These results are discussed in terms of current understanding of the hydrogel relaxation dynamics and particular attention is paid to the issue of the chain dynamics between aggregated cores.
Enhancing gas–liquid volumetric mass transfer coefficient
Dongil Ho,Kwangmin Kim,Taeshik Earmme,Choongik Kim 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.87 No.-
Methane-based biorefineries for biofuel production by microorganisms has gained interest due to theworldwide development of shale gas as an alternative source for fossil fuels. For the practical applicationof biological conversion process to industrial scale, enhancement of the gas–liquid volumetric masstransfer coefficient (kLa) in a gas diffusing system is crucial. This review article provides an overview ofthe developments on gas–liquid volumetric mass transfer enhancement through increasing the gas–liquid mass transfer coefficient term ‘kL’ and/or increasing the gas–liquid interfacial area term ‘a’. Twomajor enhancement methods which are summarized and discussed here include the most recentaccomplishments in gas–liquid mass transfer engineering of gas diffusing systems. The most up-to-datemechanical modification of reactor and additive employment rationales and discussions providing astrong understanding of gas–liquid volumetric mass transfer relationships are presented. Thus, thisreview is expected to inspire new research for future developments and applications in gas–liquid masstransfer engineering for gas diffusing systems.
Polyurethane triblock copolymer gate dielectrics for low-voltage organic thin-film transistors
Kim, Dongkyu,Kim, Choongik,Earmme, Taeshik Elsevier 2019 Journal of industrial and engineering chemistry Vol.71 No.-
<P><B>Abstract</B></P> <P>Novel polyurethane triblock copolymers comprising polycaprolactone diol (PCL), 1,6-hexamethylene diisocyanate (HMDI), and polyethylene glycol (PEG) were synthesized for use as gate dielectric for organic thin-film transistors (OTFTs). Thin films of polyurethane gate dielectrics processed from solution exhibit excellent insulating properties (∼7×10<SUP>−7</SUP> A/cm<SUP>2</SUP> at 1V) as well as large areal capacitance (170nF/cm<SUP>2</SUP>) with film thickness of ∼50nm. OTFTs are fabricated with representative n-channel organic semiconductor (N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide; PTCDI-C13) using the developed gate dielectrics, and the resulting devices show decent electrical performance with negligible hysteresis at low operating voltage of 1V.</P>
Minjeong Lee,윤승재,Dongil Ho,Taeshik Earmme,Assunta Marrocchi,Luigi Vaccaro,김충익 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.105 No.-
In the trends of ever-growing worldwide interest for the environment/health and the corresponding legalregulations, there have been various studies to replace toxic halogenated/aromatic hydrocarbon organicsolvents commonly used in the solution-processing of organic semiconductors (OSCs) with more sustainablegreen solvents. In this paper, we fabricated ambipolar organic thin-film transistors (OTFTs) andcomplementary-like inverters by blending a p-type OSC (6,13-bis(triisopropylsilylethynyl)pentacene;TIPS-pentacene) and a n-type OSC (N,N’-di-n-octyl-3,4,9,10-perylenetetracarboxylic diimide; PTCDI-C8)in a single green solvent anisole. In particular, shellac was employed as green dielectric materials andthe electrical performance of the resulting devices were compared with those fabricated using toxic solventsor commonly used oxide-based dielectrics. The bulk-heterojunction (BHJ)-structured OTFTs in theoptimized condition exhibited typical ambipolar characteristics with relatively balanced charge carriermobilities as high as 0.042 and 0.14 cm2 V 1s 1 for hole and electron, respectively. Additionally,complementary-like inverters based on the two optimized ambipolar OTFTs showed a decent transfergain as high as 21 at negative supply voltages of 60 V. Thus, by demonstrating the applicability of greensolvents not only for OTFTs but also in the implementation of circuit devices, we expect that the resultsobtained will spark more interest for the more sustainable fabrication of OSC-based electronic devicesand their commercialization/mass-production in the relevant industrial real cases.
Sungmin Cho,Dongkyu Kim,Yeongkyu Yun,Jeongyeon Lee,Taeshik Earmme,SungYong Seo,Choongik Kim 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-
Solid polymer electrolyte gate dielectric based on cross-linked poly(ethylene oxide) (CPEO) was developed and employed for organic thin-film transistors (OTFTs). Mechanical stability, high areal capacitance, and amorphous morphology of CPEO were achieved via the use of polyhedral oligomeric silsesquioxane (POSS) as cross-linker, dissolved ion [EMIM][TFSI] as electrolyte, and PEO with low molecular weight as polymer matrix, respectively. The resulting solid polymer electrolyte showed excellent insulating properties with low leakage current density (1.8 × 10−7 A cm−2 at 1 V) and high capacitance per area (∼ 1 μF cm−2 at 100 Hz). Furthermore, dielectric properties of the developed polymer electrolytes including ionic conductivity as well as segmental relaxation time were investigated. The polyelectrolyte dielectric was employed for bottom-gate/top-contact organic thin-film transistors and the resulting devices showed decent electrical performance with a carrier mobility of 0.12 (±0.03) cm2 V−1 s−1 and a current on/off ratio of 103 at low operating voltage of 5 V.
Woobyung Park,Chaeyoung Yun,Seungjae Yun,이재진,배상욱,호동일,Taeshik Earmme,김충익,SungYong Seo 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.114 No.-
Liquid crystalline organic semiconductors have drawn tremendous interest due to potentials of applicationsin organic thin-film transistors (OTFTs) with their high electrical performance and solutionprocessability. However, alkylated liquid crystals often encounter poor thermal durability and mobilitydrop at smectic E (SmE) phase. Here, we introduce new solution-processable [1]benzothieno[3,2-b][1]benzothiophene-based small molecules with different types of alkyl side chains for OTFTs. All BTBT derivativesshowed smectic phase; dialkylated 2-octyl-7-(50-octyl-[2,20-bithiophen]-5-yl)benzo[b]benzo[4,5]thieno[2,3-d]thiophene (O-2Th-BTBT) and 2-(50-(2-ethylhexyl)-[2,20-bithiophen]-5-yl)-7-octylbenzo[b]benzo[4,5]thieno[2,3-d]thiophene (E-2Th-BTBT) suffered mobility degradation at SmE phase. However,monoalkylated 2-([2,20-bithiophen]-5-yl)-7-octylbenzo[b]benzo[4,5]thieno[2,3-d]thiophene (2Th-BTBT)did not exhibit SmE phase over temperature range, resulting in high carrier mobility up to 0.31 cm2/Vsthrough molecular bilayer transition by thermal annealing. Physicochemical and liquid crystal propertieswere analyzed, and thin film characterization by atomic force microscopy and X-ray diffraction wasdiscussed.