Electrohydrodynamic printing for scalable MoS₂ flake coating: application to gas sensing device

Lim, Sooman,Cho, Byungjin,Bae, Jaehyun,Kim, Ah Ra,Lee, Kyu Hwan,Kim, Se Hyun,Hahm, Myung Gwan,Nam, Jaewook IOP 2016 Nanotechnology Vol.27 No.43

<P>Scalable sub-micrometer molybdenum disulfide (<img ALIGN='MIDDLE' ALT='${\mathrm{MoS}}_{2}$' SRC='http://ej.iop.org/images/0957-4484/27/43/435501/nanoaa3ca9ieqn1.gif'/>) flake films with highly uniform coverage were created using a systematic approach. An electrohydrodynamic (EHD) printing process realized a remarkably uniform distribution of exfoliated <img ALIGN='MIDDLE' ALT='${\mathrm{MoS}}_{2}$' SRC='http://ej.iop.org/images/0957-4484/27/43/435501/nanoaa3ca9ieqn2.gif'/> flakes on desired substrates. In combination with a fast evaporating dispersion medium and an optimal choice of operating parameters, the EHD printing can produce a film rapidly on a substrate without excessive agglomeration or cluster formation, which can be problems in previously reported liquid-based continuous film methods. The printing of exfoliated <img ALIGN='MIDDLE' ALT='${\mathrm{MoS}}_{2}$' SRC='http://ej.iop.org/images/0957-4484/27/43/435501/nanoaa3ca9ieqn3.gif'/> flakes enabled the fabrication of a gas sensor with high performance and reproducibility for <img ALIGN='MIDDLE' ALT='${\mathrm{NO}}_{2}$' SRC='http://ej.iop.org/images/0957-4484/27/43/435501/nanoaa3ca9ieqn4.gif'/> and <img ALIGN='MIDDLE' ALT='${\mathrm{NH}}_{3}$' SRC='http://ej.iop.org/images/0957-4484/27/43/435501/nanoaa3ca9ieqn5.gif'/>.</P>

Design of Coaxial Slot-Sleeve Type Applicator

Sooman Park,Yeongseog Lim 한국통신학회 2005 한국통신학회 학술대회논문집 Vol.2005 No.6

Fabrication of Copper Nanoparticles Incorporated P3HT: PCBM Solar Cell with solution processes

Manoj Ovhal,Sooman Lim(임수만),Jaewook Kang(강재욱) 융복합지식학회 2019 융복합지식학회논문지 Vol.7 No.1

본 연구는 용액공정 즉, 스핀 코팅, 바 코팅 및 스크린 프린팅 공정을 이용하여 구리나노입자 첨가형 P3HT : PCBM 태양 전지를 제조하였고 생산 된 효율을 비교 하였다. 여기서,은 (Ag) 상부 전극은 금속 증착에 의해 증착되고 미리 증착 된 폴리머 박막 상에 스크린 인쇄로 인쇄하여 비교실험하였다. 시트 저항 (Rsh)은 각각 0.7 Ω □<SUP>-1</SUP> 및 2 Ω □<SUP>-1</SUP> 이었고, 두께는 100 nm 및 80 nm이었다. 그 결과, OPV에서 스핀 코팅 및 바 코팅을 하고 금속 증착 된 효율은 각각 4.39 및 0.63 %의 효율을 나타냈지만 스크린 인쇄 된 Ag 전극 OPV는 단락문제를 야기시켰다. 이것은 스크린 인쇄기 압착기가 OPV에 가한 인장력으로 인해 활성층 구조가 데미지를 입었기 때문으로 사료된다. 한편, 스핀 코팅 공정은 주변 조건에서 수행 된 바 코팅 공정에 비해 신뢰성이 높았으나, 바 코팅으로 처리된 활성층은 OPV 구조에서 대면적 제조용으로 사용될 가능성을 볼 수 있었다. 그러나 스크린 프린팅의 경우, OPV 제조 공정에서 스크린 프린팅 공정을 채택하기 위해서는 스퀴즈로 인한 상층 손상을 제거하기위한 더 많은 연구가 필요하다. The present work is mainly focused on fabrication of copper nanoparticles incorporated P3HT: PCBM solar cell top electrode with spin coating, bar coating and screen-printing process and the efficiency produced by each method was compared. Herein, Silver (Ag) top electrode deposited by metal evaporation and screen printing on pre-deposited polymeric thin film. The sheet resistance (Rsh) of Ag electrodes were 0.7 Ω □<SUP>-1</SUP> and 2 Ω □<SUP>-1</SUP> with the thickness of 100 nm and 80 nm respectively. As a result, the metal evaporated Ag electrode based OPV coated by spin coating and bar coating in active layer shows 4.39 and 0.63 % efficiency, respectively. Whereas, the screen-printed Ag electrode OPVs were shorts. This short problem was raised due to the impression force applied by screen printer squeezer on the OPVs. Although spin coating process was more reliable compared with bar coating process performed in ambient condition, bar coated active layer has shown possibility to be used in OPV structure. For screen printing, however, more research to remove upper layer damage caused by squeezing was required to adapt screen-printing process in the OPV fabrication process.

PEDOT:PSS Overcoating Layer for Mechanically and Chemically Stable Ag Nanowire Flexible Transparent Electrode

Hwang, Byungil,Lim, Sooman Hindawi Limited 2017 Journal of nanomaterials Vol.2017 No.-

<P>We investigated the effect of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) deposition on the chemical and mechanical stability of Ag nanowire flexible electrodes. A large number of bending cycles, up to 500,000 cycles, were imposed on the Ag nanowire electrodes with and without PEDOT:PSS overcoating layer. In situ resistance measurement during bending tests revealed that the Ag nanowire electrode with PEDOT:PSS overcoating layer was mechanically reliable, showing a 21.9% increase in resistance after 500,000 cycles of bending. Scanning electron microscope images revealed that the failure of the Ag nanowire network occurred along with cracks initiated in the PEDOT:PSS layer, which resulted in the increase in resistance under bending. Furthermore, the PEDOT:PSS deposition enhanced the chemical stability of Ag nanowire electrode, which showed no significant increase in resistance after exposure in air for 50 days. Our study underscored that PEDOT:PSS is effective in protecting the Ag nanowires, while maintaining the high mechanical stability.</P>

Fluorinated Polyimide Gate Dielectrics for the Advancing the Electrical Stability of Organic Field-Effect Transistors

Baek, Yonghwa,Lim, Sooman,Yoo, Eun Joo,Kim, Lae Ho,Kim, Haekyoung,Lee, Seung Woo,Kim, Se Hyun,Park, Chan Eon American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.17

<P>Organic field-effect transistors (OFETs) that operated with good electrical stability were prepared by synthesizing fluorinated polyimide (PI) gate dielectrics based on 6FDA–PDA–PDA PI and 6FDA–CF3Bz–PDA PI. 6FDA–PDA–PDA PI and 6FDA–CF3Bz–PDA PI contain 6 and 18 fluorine atoms per repeat unit, respectively. These fluorinated polymers provided smooth surface topographies and surface energies that decreased as the number of fluorine atoms in the polymer backbone increased. These properties led to a better crystalline morphology in the semiconductor film grown over their surfaces. The number of fluorine atoms in the PI backbone increased, the field-effect mobility improved, and the threshold voltage shifted toward positive values (from −0.38 to +2.21 V) in the OFETs with pentacene and triethylsilylethynyl anthradithiophene. In addition, the highly fluorinated polyimide dielectric showed negligible hysteresis and a notable gate bias stability under both a N<SUB>2</SUB> environment and ambient air.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-17/am5035076/production/images/medium/am-2014-035076_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5035076'>ACS Electronic Supporting Info</A></P>

Electrohydrodynamic (EHD) jet printing of carbon-black composites for solution-processed organic field-effect transistors

Li, Xinlin,Go, Myeongjong,Lim, Sooman,An, Tae Kyu,Jeong, Yong Jin,Kim, Se Hyun Elsevier 2019 Organic electronics Vol.73 No.-

<P><B>Abstract</B></P> <P>In this study, carbon-black (CB) conductive electrodes were successfully printed using the high-resolution electrohydrodynamic (EHD) jet printing technique. The wrapping of CB bundles with a polymeric surfactant, Triton X-100 (TX-100), enabled the CB/TX-100 composites to well disperse in ethanol/deionized water for use in the preparation of conductive inks for EHD jet printing. By adjusting the voltage and operation distance, the applied electrostatic and gravity forces to the loaded CB/TX-100 inks overcame the fluid forces (viscosity and surface tension) to elongate the droplet and provide continuous jet lines, where the ink widths were smaller than the diameter of the nozzle. The EHD-printed CB/TX-100 in the stable cone-jet mode formed conductive lines and various pattern shapes. These conductive lines were utilized as source and drain electrodes of organic field-effect transistors (OFETs) with solution-processed organic semiconductors. The OFET with printed CB/TX-100 electrodes exhibited better electrical performances, including a higher saturation mobility and smaller hysteresis, than those of the reference OFET with Au electrodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Carbon black/Triton X-100 surfactant composite solutions are prepared for EHD printing. </LI> <LI> CB patterns are successfully printed under stable cone-jet and exhibit good conductivity. </LI> <LI> OFETs with EHD-printed CB exhibited better performances with negligible hysteresis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

스크린 프린팅 기술로 제작된 종이기반 Ag/CNT nanocomposite 스트레인 센서의 인쇄적성

제설(Xue Qi),임수만(Sooman Lim) 융복합지식학회 2021 융복합지식학회논문지 Vol.9 No.1

인쇄전자 기반으로 제작된 종이 기반 스트레인 센서는 다양한 응용 분야가 있으며, 특히 저항 기반 센서는 환경 친화적이며 웨어러블 장치에 사용할 수 있어 천천히 변화하는 변형, 무거운 하중을 받는 구조 또는 극한 이벤트로 인한 예기치 않은 영향을 감지하는데 적합하다. 본 연구에서는 Ag/CNT 스크린 프린팅 공정을 사용하여 GF 20 이상의 종이 기반 스트레인 센서를 제작하였고 인쇄적성에 따른 센서 제작 및 센싱 효과를 체계적으로 분석하였다. 그 결과, gap이 0.38에서 0.5 mm로 증가할 경우 선폭이 546 um에서 최대 396 um로 감소함 확인하였고 스퀴지가 스크린 메쉬에 5 mm에서 9 mm로 가까워질수록 패턴 폭은 581에서 721 um로 증가됨을 볼 수 있었다. 또한, 100°C에서 저항값이 352 Ω에서 220°C일 때 100 Ω까지 감소하였는데 이러한 온도 변화는 Ag/CNT의 결합구조에 영향을 미치고 이는 감도 차이를 생성함을 확인할 수 있었다. 이를 통해 스크린 프린팅 공정으로 종이기반 스트레인 센서 기술 개발을 위한 의미 있는 기본 데이터로 사용될 수 있다고 사료된다. Paper-based strain sensors produced based on printed electronics have a variety of applications for slowly changing deformation, heavy-loaded structures, or extreme events. Especially resistance-based sensors which can be used in wearable devices, are affected by printability. In this study, a strain sensor based on GF 20 or higher was fabricated using the Ag/CNT screen printing process, and the sensor fabrication and sensing effects were systematically analyzed according to its printability. As a result, when the gap between mesh and sbustrate is increased from 0.38 to 0.5 mm, line width decreases from 546 um to a maximum of 396 um. As the confirmed squeegee approaches the screen mesh from 5 mm to 9 mm, the pattern width increases from 581 to 721 um. In addition, it can be seen that the resistance value decreases from 352 Ω to 100 Ω when drying temperature increased from 100°C to 220°C, which is attributed to the bonding structure of Ag/CNTs and creates a sensitivity difference. Through this, it is considered a number of meaningful basic data for the development of paper-based strain sensor technology as a screen printing process.

Patterned silver nanowires using the gravure printing process for flexible applications

Park, Jong Deck,Lim, Sooman,Kim, Haekyoung Elsevier 2015 THIN SOLID FILMS - Vol.586 No.-

<P><B>Abstract</B></P> <P>Gravure printing is a promising electronics printing technology for fabricating flexible-large area devices at high speeds. Ag nanowire (Ag NW)-based transparent conductive electrodes are excellent candidates for replacing indium thin oxide in flexible electronics and optical devices, which require the preparation of patterned structures. Here, the gravure printing processing parameters for applying Ag NW ink were investigated to produce large-area patterned transparent and uniform Ag NW lines on polyethylene terephthalate substrates. The ink transfer properties changed with the printing speed and pressure, as discussed, and these parameters modulated the electrical properties of the printed Ag NWs annealed at various temperatures. The importance of the rheological behavior of the ink, the printing speed, and the pressure was confirmed to understand the mechanism underlying Ag NW ink transfer. The printed line resistance for a 450μm of line width dried at 90°C was 32Ωmm<SUP>−1</SUP> with a 95% of transmittance and a 100μm gap between the printed lines. The line width and spacing of the printed patterned Ag NWs may be controlled using the parameters examined here to optimize the application-specific device performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Patterned Ag NW conductive lines were fabricated with the gravure printing method. </LI> <LI> The parameters for printing were investigated. </LI> <LI> The printed line width was 450μm and 100μm gap between the printed lines. </LI> <LI> The resistance was 32Ωmm<SUP>−1</SUP> and transmittance was 95%. </LI> <LI> The parameters examined here used to optimize the application-specific device performance. </LI> </UL> </P>

Li₂SO₄ 및 Na₂SO₄ 전해질에서 수열방식으로 합성된 CoSe의 전기화학 성능 특성에 관한 연구

( Asrar Alam ),임수만 ( Sooman Lim ) 한국화상학회 2019 한국화상학회지 Vol.25 No.4

본 연구는 1M Li₂SO₄ 및 1M Na₂SO₄ 수용액에서 CoSe 나노 입자의 전기 화학적 성능을 조사 하 였다. CoSe 나노 입자의 전기 화학적 효율은 1M Na₂SO₄ 전해질에서 더 높은 비정전 용량을 보여주는 결 과를 얻었고 이것은 주로 1M Na₂SO₄ 용액의 벌크 전해질에서 수화 된 이온의 빠른 이동과 활물질에 의 해 제공되는 낮은 전기 화학적 임피던스가 원인이라 사료된다. 또한, 순환 전압 전류 법 안정성 실험에서 25 mV s-1의 스캔 속도로 1000 회 연속 순환 전압 전류 측정주기 후에도 각각 1M Na₂SO₄ 및 1M Li₂SO₄에서 약 92 % 및 89 %의 특정 정전 용량의 유지를 보여주었다. 이 연구는 새로운 하이브리드 슈퍼 커패시터를 개발하기 위한 기초 데이터를 제공하며 비대칭 슈퍼 커패시터의 양극으로 사용될 수 있음을 시사한다. The electrochemical performance of CoSe nanoparticles in 1M Li₂SO₄ and 1M Na₂SO₄ aqueous electrolytes solution were investigated. The electrochemical studies of CoSe nanoparticles shows higher specific capacitance in 1M Na₂SO₄ electrolyte. This is mainly due to low electrochemical impedance offered by active material and fast speed migration of hydrated ions in bulk electrolyte of 1M Na₂SO₄ solution. In addition, cyclic voltammetry stability study shows retention of specific capacitance about 92% and 89% in 1M Na₂SO₄ and 1M Li₂SO₄ respectively, even after 1000 continuous cyclic voltammetry cycles at a scan rate of 25 mV s^-1. This study provides valuable data to develop new hybrid supercapacitor and can be used as a positive electrode for an asymmetric supercapacitor.

한국형 자연순환 태양열온수기 개발 및 평가

백남춘(NamChoon Baek),이수만(SooMan Lee),김동윤(DongYun Kim),임희원(HeeWon Lim),신우철(UCheul Shin) 한국신재생에너지학회 2017 한국신재생에너지학회 학술대회논문집 Vol.2017 No.5