Highly stretchable fiber transistors with all-stretchable electronic components and graphene hybrid electrodes

Lee, Wonoh,Kim, Youn,Lee, Moo Yeol,Oh, Joon Hak,Lee, Jea Uk Elsevier 2019 Organic electronics Vol.69 No.-

<P><B>Abstract</B></P> <P>Textile-based electronic devices should be not only bendable but also highly stretchable for human-friendly wearable electronic applications. Herein, a highly stretchable and mechanically durable fiber transistor was designed and prepared by combining all-stretchable electronic components. First, electrically conductive and stretchable electrodes were fabricated by simple prestraining-then-buckling of graphene/silver hybrid fibers on a highly elastic thermoplastic polyurethane (TPU) monofilament, which maintained a low resistivity (∼30 Ω cm) at a high stretching strain (∼70%) and under many stretch/release cycles (∼1,000). A highly stretchable active channel was prepared by directly blending semiconducting poly(3-hexylthiophene) (P3HT) and viscoelastic TPU without using pre-grown P3HT nanofibrils. The P3HT/TPU blend (5/5 w/w blend ratio) active layer possessed reasonably high mobility (1.46 × 10<SUP>−3</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>) and adequate mechanical strength (21 MPa) with a high elongation strain (∼120%). In addition, a stretchable dielectric layer and gate electrode were prepared using an elastic ion-gel film and a liquid metal composite, respectively. The assembled fiber transistor exhibited excellent stretchability (∼50%) while maintaining good electrical properties (average charge carrier mobility of 1.74 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, on/off current ratio of 10<SUP>4</SUP>) and showed outstanding electrical stability up to 1,000 cycles of stretch/release testing. To the best of our knowledge, these superior stretchability and stability have not been reported elsewhere in the area of fiber-type transistors. We believe that our work can serve as an important step toward the development of core components in wearable devices, such as wearable displays, computers, and biomedical sensors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Buckled graphene/Ag hybrid fiber electrodes maintained low resistivity at high stretching strain. </LI> <LI> Stretchability and stability of fiber transistor are superior to other fiber transistors. </LI> <LI> Assembly method of stretchable electronic components are applicable to wearable devices. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fabrication of Carbon Nanotube/Copper Hybrid Nanoplatelets Coated Carbon Fiber Composites by Thermal Vapor and Electrophoretic Depositions

Lee, Wonoh,Lee, Sang-Bok,Yi, Jin-Woo,Kim, Byung-Sun,Byun, Joon-Hyung The Electrochemical Society 2011 Electrochemical and solid-state letters Vol.14 No.7

Constitutive Equations Based on Cell Modeling Method for 3D Circular Braided Glass Fiber Reinforced Composites

Lee, Wonoh,Kim, Ji Hoon,Shin, Heon-Jung,Chung, Kwansoo,Kang, Tae Jin,Youn, Jae Ryoun The Korean Fiber Society 2003 Fibers and polymers Vol.4 No.2

The cell modeling homogenization method to derive the constitutive equation considering the microstructures of the fiber reinforced composites has been previously developed for composites with simple microstructures such as 2D plane composites and 3D rectangular shaped composites. Here, the method has been further extended for 3D circular braided com-posites, utilizing B-spline curves to properly describe the more complex geometry of 3D braided composites. For verification purposes, the method has been applied for orthotropic elastic properties of the 3D circular braided glass fiber reinforced com-posite, in particular for the tensile property. Prepregs of the specimen have been fabricated using the 3D braiding machine through RTM (resin transfer molding) with epoxy as a matrix. Experimentally measured uniaxial tensile properties agreed well with predicted values obtained for two volume fractions.

Layer-by-Layer Assembly for Graphene-Based Multilayer Nanocomposites: Synthesis and Applications

Lee, Taemin,Min, Sa Hoon,Gu, Minsu,Jung, Yun Kyung,Lee, Wonoh,Lee, Jea Uk,Seong, Dong Gi,Kim, Byeong-Su American Chemical Society 2015 Chemistry of materials Vol.27 No.11

<P>Two-dimensional (2D) graphene sheets have become a versatile platform for the fabrication of innovative hybrid materials with various functions due to their unique electrical, optical, thermal, and mechanical properties. The preparation of graphene-based composites with nanoscale precision is highly important for reproducible and controllable performance through the analysis of interplay between each component. In particular, the layer-by-layer (LbL) assembly technique is known as a simple, inexpensive, and versatile process for the fabrication of highly ordered multilayer film structures from various types of materials. The LbL structures capable of controlling nanoscale composition and architectures are achieved through the sequential adsorption of oppositely charged components by attractive forces such as electrostatic interactions. In this review, we will focus on the recent progress in graphene-based nanocomposites hybridized with various nanomaterials such as carbon nanomaterials, polymers, and inorganic nanoparticles by the LbL assembly. Multilayered graphene nanocomposites exhibit improved physical/chemical properties and superior performance compared with the individual components due to the synergistic effects in various applications including electric devices, energy storage and conversion, and biological usages.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-11/acs.chemmater.5b00491/production/images/medium/cm-2015-00491c_0013.gif'></P>

Highly Sensitive Ultraviolet Light Sensor Based on Photoactive Organic Gate Dielectrics with an Azobenzene Derivative

Lee, Kang Eun,Lee, Jea Uk,Seong, Dong Gi,Um, Moon-Kwang,Lee, Wonoh American Chemical Society 2016 The Journal of Physical Chemistry Part C Vol.120 No.40

<P>Photochromic molecules have been recently adopted by many researchers for organic field-effect transistor (OFET) applications, since they offer the opportunity to achieve flexible-type ultraviolet (UV) light sensors with the advantages of organic material-based solution processes. Here, we present the novel usage of an azobenzene derivative in the gate dielectric layer of an OFET for highly sensitive and reliable UV sensing applications. Owing to the large change of capacitance caused by the reversible photoisomerization of azobenzene, the OFET device can modulate efficiently the current. signal under UV and visible light. We found that the on-current was greatly amplified upon UV light irradiation with good photoresponsivity and photocurrent ratio and then fully returned to the initial state under visible light. In addition, the device shows a strongly linear relationship with the UV radiation intensity and repetitive on off response in real-time UV sensing tests, thus being potentially applied in highly sensitive and reliable UV sensors.</P>

열가소성 유리섬유/PP 복합재의 반구돔 열성형 평가 및 비직교 구성방정식을 이용한 FEM 수치해석

이원오 ( Wonoh Lee ) 한국복합재료학회 2016 Composites research Vol.29 No.5

본 연구에서는 유리섬유/폴리프로필렌 기반의 열가소성 복합재의 열성형 시험 평가를 위해, 성형온도에서의 인장 및 면내 전단 물성 시험을 실시하였고, 이를 비직교 구성방정식을 이용하여 정량화 하였다. 이를 통해 실험값과 잘 일치하는 고온에서의 인장 및 전단 물성값을 수식화하여 얻을 수 있었다. 열성형 시험을 위해 반구돔 시험을 실시하였고, 이형제 사용 유무 및 홀더의 무게를 달리해가며 성형품의 최종형상을 비교하였다. 그 결과 이형제를 사용하면 성형품의 대칭성이 확보되고 주름 개선 효과에 유리하다는 것을 확인하였고, 적당한 힘의홀딩력 제어가 필수적이라는 것을 알 수 있었다. 더 나아가 비직교 구성방정식이 고려된 열성형 수치해석을 실시하여 실험 결과와 유사한 양상을 확인할 수 있었고, 홀딩력이 낮을 수록 주름이 많아지고, 마찰력이 클수록 더 많은 펀치력을 필요로 함을 확인하였다. In this work, tensile and in-plane shear tests for thermoplastic glass fiber/polypropylene composites were performed at a thermo-forming temperature and their properties were characterized and mathematically expressed by using the non-orthogonal constitutive model. As for the thermo-forming test, half-dome experiments were carried out by varying the usage of a releasing agent and the weight of holders. As results, the optimum final shape having wellaligned symmetry and no wrinkle formation was obtained when the releasing agent was used, and it was found that the careful control of a holding force is crucial to manufacture the healthy product. Furthermore, FEM simulations based on the non-orthogonal model showed similar final shapes and tendency of wrinkle formation with experimental results, and confirmed that wrinkles increase with less holding force and higher punch force is required under high frictional condition.

아민 분자로 개질된 그래핀 섬유의 제조 및 응용

이원오 ( Wonoh Lee ),윤상수 ( Sangsu Yoon ),엄문광 ( Moonkwang Um ),이재욱 ( Jeauk Lee ) 한국복합재료학회 2015 Composites research Vol.28 No.5

최근에 각광을 받고 있는 섬유강화 복합재료, 웨어러블 전자소자, 그리고 전자파 차폐재료 같은 다양한 응용분야에 적용하기 위해서, 높은 기계적·전기적 특성을 갖는 그래핀 섬유를 대량으로 생산하는 일은 산업적으로 매우 의미가 있다. 본 연구에서는 다이-아민 그룹으로 화학적 치환 된 산화 그래핀을 습식 방사 공정을 통하여 섬유로 제조하는 효율적인 공정을 개발하였다. 다이-아민 그룹으로 치환된 산화 그래핀은 합성이 용이하고 수용액에서 분산성이 매우 좋으며, 저렴한 비용으로 대량 생산이 가능한 장점을 가지고 있다. 이렇게 제조된 아민-치환 그래핀 섬유는 산화 그래핀 섬유와 비교해서 높은 기계적, 전기적 특성을 보이기 때문에 웨어러블 전자 소자에 응용이 기대된다. Development of simple and efficient method for large-scale production of mechanically strong and electrically conductive graphene fiber is highly desirable for practical applications, such as fiber-reinforced composites, wearable electronics, and electromagnetic irradiation shielding. Here, we present a facile approach for the preparation of amine-functionalized graphene fibers by simple wet-spinning of diamine-functionalized graphene oxide (GO-NH2), which is used because of its synthetic convenience, good dispersity, and scalable production with low cost. The aminefunctionalized graphene fiber shows high electrical and mechanical properties compared to pristine graphene oxide fiber due to the electrostatic interaction between amine groups and electronegative functional groups of graphene oxide.

Fabrication of Three-dimensional Aramid Nanostructures assisted through Covalent Bonding

Guk-Hwan Lee(이국환),Wonoh Lee(이원오) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

Fabrication of Three-dimensional Aramid Nanostructures assisted through Covalent Bonding

Guk-Hwan Lee(이국환),Wonoh Lee(이원오) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

Fabrication of Hierarchically Porous Silica Aerogels using Aramid Nanostructures

Guk-Hwan Lee(이국환),Wonoh Lee(이원오) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11