• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.144.1-144.1
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• 2016

We fabricate organic single crystal nanowire heterojunction p-n diode poly(3-hexylthiophene)(P3HT) and from Phenyl-C61-butyric acid methyl ester(PCBM) using by liquid-bridge mediated nanotransfer molding(LB-nTM) method. LB-nTM has been reported an one step direct printing method for making well-aligned nanowire arrays. Moreover, multi-patterning nanostructures can be fabricated with the consecutive printing process. As a result, it is possible to make simple and basic concept of heterojunction devices such as lateral organic p-n nanojunction diode. P3HT/PCBM nanowires heterojunction diode has rectifying behavior with on/off ratios of ~20.

• 한국재료학회지
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• 제34권8호
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• pp.395-399
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• 2024

Among various organic materials suitable for silicon-based inorganic-organic hybrid solar cells, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has been extensively studied due to its high optical transmittance, high work function, and low bandgap characteristics. The electro-optical properties of PEDOT:PSS have a significant impact on the power conversion efficiency of silicon-organic hybrid solar cells. To enhance the photovoltaic properties of the silicon-organic hybrid solar cells, we developed a method to improve the properties of the PEDOT:PSS film using Ag nanowires (NW) instead of conventional solvent addition methods. The influence of the Ag NW on the electro-optical property of the PEDOT:PSS film and the photovoltaic performance of the silicon-organic hybrid solar cells were investigated. The addition of Ag NW further improved the sheet resistance of the PEDOT:PSS film, enhancing the performance of the silicon-organic hybrid solar cells. The present work using the low sheet resistance PEDOT:PSS layer paves the way to develop simple yet more efficient silicon-organic hybrid solar cells.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.92.1-92.1
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• 2013

Molecular electronics has been the subject of intese research for many years because of the fundamental interest in molecular charge transport and potential applications, such as (bio)nanosensors and molecular memory devices. Molecular electronics requires a method for making reliable eletrical contacts to singlemolecules. To date, several approaches have been reported: scanning-probe microscopy, mechanical break junctions, nano patterning, and direct deposition of electrode on a self-assembled monolayers. However, most methods are laborious and difficult for large-scale application and more importantly, cannot control the number of moleucles in the junction. Recently, DNA has been used as a template for metallic nanostructures (e.g., Ag, Pd, and Au nanowires) through DNA metallization process. Furthermore, oligodeoxynucleotides have been tethered to organic molecules by using conventional organic reactions. Collectively, these techniques should provide an efficient route toward reliable and reproducible molecular electronic devices with large-scale fabrication. Therefore, I will present a paradigm for the fabrication of moleuclar electronic devices by using micrometer-sized DNA-singe organic molecule and DNA triblock structures.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.328.2-328.2
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• 2014

Semiconductor nanowires (NWs) have attracted research interests due to the distinct physical properties that can lead to variousoptical and electrical applications. In this paper, we have grown InAs NWs viagold (Au)-assisted vapor-liquid-solid (VLS) and catalyst-free vapor-solid (VS) mechanisms and investigated on the p-type doping profile of the NWs. Metal-organic chemical vapor deposition (MOCVD) is used for the growth of the NWs. Trimethylindium (TMIn) and arsine (AsH3) were used for the precursor and diethyl zinc (DEZn) was used for the p-type doping source of the NWs. The effectiveness of p-type doping was confirmed by electrical measurement, showing an increase of the electron density with the DEZn flow. The structural properties of the InAs NWs were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, we characterize atomic distribution of InAs NWs using energy-dispersive X-ray spectroscopy (EDX) analysis.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.2.3-2.3
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• 2011

With increased interest in printed devices, various metal nano inks have been investigated as candidates materials for printed electrodes and wiring as well as conductive film substituting photo-lithography process. Recent advances in organic conductive polymer allow us to fabricate high performance printed device. Meanwhile, there was several attempts to fabricate conductive films by mixing conductive polymer with metal nano-particle or nano-wires. The presence of Ag nanowires in conductive polymer mixture have shown good potential in organic photovoltaic devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.158-158
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• 2011

A wide range of techniques for the direct-printing of functional materials have been developed for the fabrication of micro- and nanoscale structures and devices. Here we report a new direct patterning method, liquid bridge-mediated nanotransfer molding (LB-nTM), for the formation of two- or three-dimensional structures with feature sized as small as tens of nanometers over large areas up to 4". LB-nTM is based on the direct transfer of various materials from a mold to a substrate via a liquid bridge between them. The LB-nTM method was applied to the preparation of organic nanowire FETs on flexible substrates.

• 접착 및 계면
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• 제23권4호
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• pp.116-121
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• 2022

Organic field-effect transistor가 실제 전자 장치에 쓰이기 위해서는 유기반도체 용액공정용 미세 패터닝 기술이 요구된다. 본 연구에서는 기존의 스핀 코팅 방법보다 미세 패턴을 형성할 수 있는 소프트 리소그래피 방법이 더 우수한 전기적 특성을 가질 수 있다는 것을 확인하기 위해 비교 분석하였다. Compact Disc 표면의 나노 패턴을 이용하여 유연한 마스터 몰드를 제작하였고, 650 nm 폭의 2,7-Dioctyl [1] benzothieno [3,2-b] [1] benzo thiophene (C_8-BTBT) 나노 와이어를 얻었다. 그 결과 소프트 리소그래피 방법을 이용해 제작된 소자 이동도는 0.086 cm²/Vs이며, 스핀 코팅으로 만들어진 소자 이동도는 0.0036 cm²/Vs으로 소프트 리소그래피 방법으로 제작된 소자가 약 20배 이상 높은 이동도와 더 우수한 전기적 성능을 보였다.

• 전기전자학회논문지
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• 제13권2호
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• pp.126-131
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• 2009

Wrap-around 전계효과 트랜지스터는 채널과 전극간의 커플링을 매우 커서 채널길이가 짧아지면서 생기는 단채널효과(short channel effect)를 개선시킬 수 있는 이유로 많은 관심을 불러왔다. 본 논문에서는 실리콘 나노와이어를 이용하여 상향식의 wrap-around 전계효과 트랜지스터(FET)의 제작 공정을 소개한다. 소자의 제작 공정은 크게 전자빔 리소그래피, 유전영동(dielectrophoresis)을 이용한 나노와이어의 효과적 정렬 그리고 게이트 전극의 전기 화학적 도금(electrochemical deposition)을 이용한 생성 등의 방법들로 이루어진다. 전기 화학적 도금을 위한 용액은 독성을 띄지 않는 유기물 용액을 사용하였다. 액체 질소를 이용하여 polymethyl methacrylate(PMMA)가 전기화학적 도금시 형태를 잃지 않게 함으로써, 패터닝된 PMMA가 wrap-around 게이트 나노구조를 제작하기 위한 나노 템플릿으로 사용될 수 있도록 하였다.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.559-565
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• 2011

The following noble series of statistical copolymers, poly[(2-(3-thienyl)ethanol n-butoxycarbonylmethylurethane)-co-3-hexylthiophene] (PURET-co-P3HT), were synthesized by the chemical dehydrogenation method using anhydrous $FeCl_3$. The structure and electro-optical properties of these copolymers were characterized using $^1H$-NMR, UV-visible spectroscopy, elemental analysis, GPC, DSC, TGA, photoluminescence (PL), and cyclic voltammetry (CV). The statistical copolymers, PURET-co-P3HT (1:0, 2:1, 1:1, 1:2, 1:3), were soluble in common organic solvents and easily spin coated onto indium-tin oxide (ITO) coated glass substrates. Hybrid bulk heterojunction photovoltaic cells with an ITO/G-PEDOT/PURET-co-P3HT:PCBM:Ag nanowires/$TiO_x$/Al configuration were fabricated, and the photovoltaic cells using PURET-co-P3HT (1:2) showed the best photovoltaic performance compared with those using PURET-co-P3HT (1:0, 2:1, 1:1, 1:3). The optimal hybrid bulk heterojunction photovoltaic cell exhibits a power conversion efficiency (PCE) of 1.58% ($V_{oc}$ = 0.82 V, $J_{sc}$ = 5.58, FF = 0.35) with PURET-co-P3HT (1:2) measured by using an AM 1.5 G irradiation (100 mW/$cm^2$) on an Oriel Xenon solar simulator (Oriel 300 W).

• 한국재료학회지
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• 제22권10호
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• pp.562-568
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• 2012

Metal nanowires can be coated on various substrates to create transparent conducting films that can potentially replace the dominant transparent conductor, indium tin oxide, in displays, solar cells, organic light-emitting diodes, and electrochromic windows. One issue with these metal nanowire based transparent conductive films is that the resistance between the nanowires is still high because of their low aspect ratio. Here, we demonstrate high-performance transparent conductive films with silver nanofiber networks synthesized by a low-cost and scalable electrospinning process followed by two-step sequential thermal treatments. First, the PVP/$AgNO_3$ precursor nanofibers, which have an average diameter of 208 nm and are several thousands of micrometers in length, were synthesized by the electrospinning process. The thermal behavior and the phase and morphology evolution in the thermal treatment processes were systematically investigated to determine the thermal treatment atmosphere and temperature. PVP/$AgNO_3$ nanofibers were transformed stepwise into PVP/Ag and Ag nanofibers by two-step sequential thermal treatments (i.e., $150^{\circ}C$ in $H_2$ for 0.5 h and $300^{\circ}C$ in Ar for 3 h); however, the fibrous shape was perfectly maintained. The silver nanofibers have ultrahigh aspect ratios of up to 10000 and a small average diameter of 142 nm; they also have fused crossing points with ultra-low junction resistances, which result in high transmittance at low sheet resistance.