• 한국생산제조학회지
• /
• 제24권1호
• /
• pp.135-139
• /
• 2015

We present a fine patterning method of conductive lines on polyimide (PI) and glass substrates using silver (Ag) nanoparticles based on laser scanning. Controlled laser irradiation can realize selective sintering of conductive ink without damaging the substrate. Thus, this technique easily creates fine patterns on heat-sensitive substrates such as flexible plastics. The selective laser sintering of Ag nanoparticles was managed by optimizing the conditions for the laser scan velocity (1.0-20 mm/s) and power (10-150 mW) in order to achieve a small gap size, high electrical conductivity, and fine roughness. The fabricated electrodes had a minimum channel length of $5{\mu}m$ and conductivity of $4.2{\times}10^5S/cm$ (bulk Ag has a conductivity of $6.3{\times}10^5S/cm$) on the PI substrate. This method was used to successfully fabricate an organic field effect transistor with a poly(3-hexylthiophene) channel.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2009년도 제38회 동계학술대회 초록집
• /
• pp.301-301
• /
• 2010

In order to enhance the efficiency of the organic solar cells, the effects of plasma surface treatment with using $CF_4$ and $O_2$ gas on the anode ITO were studied. The polymer solar cell devices were fabricated on ITO glasses an active layer of P3HT (poly-3-hexylthiophene) and PCBM ([6,6]-phenyl C61-butyric acid methyl ester) mixture, without anode buffer layer, such as PEDOT:PSS layer. The metallic electrode was formed by thermally evaporated Al. Before the coating of organic layers, ITO surface was exposed to plasma made of $CF_4$ and $O_2$ gas, with/without heat treatment. In order to identify the effect the surface treatment, the current density and voltage characteristics were measured by solar simulator and the chemical composition of plasma treated ITO surface was analyzed by using X-ray photoelectron spectroscopy(XPS). In addition, the work function of the plasma treated ITO surface was measured by using ultraviolet photoelectron spectroscopy(UPS). The effects of plasma surface treatment can be attributed to the removal organic contaminants of the ITO surface, to the improvement of contact between ITO and buffer layer, and to the increase of work function of the ITO.

• 한국진공학회지
• /
• 제18권5호
• /
• pp.390-393
• /
• 2009

유기물 기반의 전자 소자에서 소자간의 전기적인 전류 흐름 및 기생저항 등을 차단하기 위하여 표면 에너지를 이용한 새로운 패터닝 기법을 제안하였다. 소수성의 perfluoro-alkyl fluorosilanes을 플라즈마 이온 에칭을 이용하여 선택적으로 친수성으로 변환한 뒤 wettability 현상을 통해 유기 물질을 자동 패터닝 하였다. 또한 이 기법을 이용하여 $V_{oc}$ (open circuit voltage): 482 mV, $J_{sc}$ (short circuit current density): 2.4 mA/$cm^2$, FF (Fill factor): 0.58, $\eta$ (Efficiency): 0.95 % 의 특성을 보이는 bulk-이종접합 유기 태양 전지 소자를 제작하였다.

• ETRI Journal
• /
• 제35권4호
• /
• pp.587-593
• /
• 2013

We demonstrate semitransparent organic photovoltaics (OPVs) based on thin metal electrodes and polymer photoactive layers consisting of poly(3-hexylthiophene) and [6,6]-phenyl $C_{61}$ butyric acid methyl ester. The power conversion efficiency of a semitransparent OPV device comprising a 15-nm silver (Ag) rear electrode is 1.98% under AM 1.5-G illumination through the indium-tin-oxide side of the front anode at 100 $mW/cm^2$ with 15.6% average transmittance of the entire cell in the visible wavelength range. As its thickness increases, a thin Ag electrode mainly influences the enhancement of the short circuit current density and fill factor. Its relatively low absorption intensity makes a Ag thin film a viable option for semitransparent electrodes compatible with organic layers.

• Bulletin of the Korean Chemical Society
• /
• 제32권2호
• /
• pp.559-565
• /
• 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
• /
• 제19권1호
• /
• pp.33-36
• /
• 2009

Inorganic-organic composite thin-film-transistors (TFTs) of ZnO nanowire/Poly(3-hexylthiophene) (P3HT) were investigated by changing the nanowire densities inside the composites. Crystalline ZnO nanowires were synthesized via an aqueous solution method at a low temperature, and the nanowire densities inside the composites were controlled by changing the ultrasonifiaction time. The channel layers were prepared with composites by spin-coating at 2000 rpm, which was followed by annealing in a vacuum at $100^{\circ}C$ for 10 hours. Au/inorganic-organic composite layer/$SiO_2$ structures were fabricated and the mobility, $I_{on}/I_{off}$ ratio, and threshold voltage were then measured to analyze the electrical characteristics of the channel layer. Compared with a P3HT TFT, the electrical properties of TFT were found to be improved after increasing the nanowire density inside the composites. The mobility of the P3HT TFT was approximately $10^{-4}cm^2/V{\cdot}s$. However, the mobility of the ZnO nanowire/P3HT composite TFT was increased by two orders compared to that of the P3HT TFT. In terms of the $I_{on}/I_{off}$ ratio, the composite device showed a two-fold increase compared to that of the P3HT TFT.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.134-134
• /
• 2012

We investigated the interface of poly (3-hexylthiophene) (P3HT) and C61-butyric acid methylester (PCBM) by using photoelectron spectroscopy (PES). These are the most widely used materials for bulk heterojunction (BHJ) organic solar cells due to their high efficiency. Study of the BHJ interfaces is difficult because the organic films are typically prepared by spin coating in ambient conditions. This is incompatible with the interface electronic structure probes such as PES, which requires ultrahigh vacuum conditions. Study of interface requires gradual deposition of thin films that is also incompatible with the spin coating process. In this work, we used electrospray vacuum deposition (EVD) technique to deposit P3HT and PCBM in high vacuum conditions. EVD allows us to form polymer thin films onto ITO substrate in a step-wise manner directly from solutions and to use PES without exposing the sample to the ambient condition. Although the morphology of the EVD deposited P3HT films observed by optical and atomic force microscopes is quite different from that of the spin coated ones, the valence region spectra were similar. PCBM was deposited on the P3HT film in a similar manner and the energy level alignment between these two materials was studied. We discuss the relation between Voc of P3HT:PCBM solar cell and HOMO-LUMO energy offset obtained in this study.

• 한국전기전자재료학회논문지
• /
• 제17권11호
• /
• pp.1212-1217
• /
• 2004

Red organic electroluminescent (EL) devices based on tris(8-hydroxyquinorine aluminum) (Alq$_3$) doped with red emissive materials, 4-(dicyanomethylene)-2-t-butyl -6-(l,1,7,7-tetramethyljulolidyl-9-enyl)4H-pyran (DCJTB). poly(3-hexylthiophene) (P3HT). rubrene and 4-dicyanomethylene-2-methyl-6[2-(2,3.6.7-tetrahydro-lH,5H-benzo-[i,j]quinolizin-8yl)vinyl]-4H-pyran (DCM2) were fabricated for applying to the red light source, The photoluminescence (pL) intensities of red emissive materials doped in Alq$_3$ are limited by the concentration quenching with increasing the doping ratio and the doping concentration of DCJTB, DCM2, P3HT and rubrene measured at the maximum intensity showed 5, 1, 0.5 and 2 wt%, respectively. Time-resolved PL dynamic results showed that the PL lifetime of red emissive materials doped in Alq$_3$ were increased more than the value of material itself. It means that the efficient energy transfer occurred in the mixed state and Alq$_3$ is a suitable host materials for red emissive materials, The device which was used DCJTB as a dopant achieved the best result of the maximum luminance of 594 cd/$m^2$ at 15 V and showed the chromaticity coordinates of x=0,624, y=0,371.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.380-380
• /
• 2012

유기물 나노 복합체는 고집적/저전력/플렉서블 특성을 가지는 초고효율 비휘발성 메모리 소자를 제작하는데 많은 이점을 가지고 있어, 차세대 비휘발성 메모리 소자에 사용되는 소재로 매우 각광받고 있다. 그 중, WORM 특성을 가지는 메모리 소자는 1회 쓰기 후 수많은 읽기가 가능하기 때문에, 그 효율성이 매우 뛰어나 이목을 끌고 있다. 유기물 나노 복합체 중에서, poly(3-hexylthiophene) (P3HT)는 화학적/전기적 안정성과 전하의 이동도 특성이 뛰어나기 때문에 전자 소자에 응용하려는 연구가 활발히 진행되고 있다. 본 연구에서는 $P_3HT$ 고분자를 polymethylmethacrylate(PMMA) 고분자에 분산시킴으로써, 상태를 기억하는 저장 매체로 사용하였다. 본 연구의 소자를 제작하기 위하여 약 9 : 1 비율을 가지는 PMMA 와 $P_3HT$를 용매인 클로로벤젠에 녹여 용액을 준비하였다. Indium Tin Oxide (ITO)가 코팅된 glass를 화학적 처리를 통해 청결하게 만든 후, PMMA와 $P_3HT$가 용해되어 있는 용액을 스핀 코팅 방법으로 박막을 형성하였다. PMMA 속에 $P_3HT$가 분산되어 있는 활성층 위에 상부 전극으로 Al을 열 증착 방식을 통하여 형성하였다. 제작된 WORM 특성을 갖는 유기물 나노 복합체 플렉서블 소자의 메모리 효과에 대한 분석을 위하여, -5V에서 5V까지 전압을 인가하여 전류-전압 특성을 측정하였다. 초기 낮은 전도도 (OFF 상태, 10-10A에서 10-4A)를 유지하다가, 쓰기 전압을 1회 가해준 후부터는 높은 전도도 (ON 상태, 10-5A 에서 10-2A)를 유지하는 특성을 관측하였다. 또한 WORM 특성을 갖는 메모리 소자로써의 능력을 보여주기 위하여, 1회 쓰기 전압 후 읽기 전압인 1V를 인가하여 높은 전도도 상태에 대한 상태 유지 능력을 측정하였고, 전하 수송 메커니즘을 규명하기 위하여 피팅 모델을 통해 설명하였다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.410.2-410.2
• /
• 2016

Tandem structure is promising in organic solar cells because of its double open-circuit voltage (VOC) and efficient photon energy conversion. In a typical tandem device, the two single sub-cells are stacked and connected by an interconnecting layer. The fabrication of two sub-cells are usually carried out in a glovebox filled with nitrogen or argon gas, which makes it expensive and laborious. We report a glovebox-free fabricated inverted tandem organic solar cells wherein the tandem structure comprises sandwiched interconnecting layer based on p-doped hole-transporting, metal, and electron-transporting materials. Complete fabrication process of the tandem device was performed outside the glove box. The tandem solar cells based on poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61-butyric acid methyl ester (PCBM) can realize a high VOC, which sums up of the two sub-cells. The tandem device structure was ITO/ZnO/P3HT:PCBM/PEDOT:PSS/MoO3/Au/Al/ZnO-d/P3HT:PCBM/PEDOT:PSS/Ag. The separate sub-cells were morphologically and thermally stable up to 160 oC. The high stability of the active layer benefits in the fabrication processes of tandem device. The performance of tandem organic solar cells comes from the sub-cells with an 50 nm thick active layer of P3HT:PCBM, achieving an average power conversion efficiency (PCE) of 2.9% (n=12) with short-circuit current density (JSC) = 4.26 mA/cm2, VOC = 1.10 V, and fill factor (FF) = 0.62. Based on these findings, we propose a new method to improve the performance and stability of tandem organic solar cells.