• Journal of the Semiconductor & Display Technology
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• v.14 no.1
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• pp.61-65
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• 2015

We have fabricated poly(3,4-ethylenedioxythiophene) : poly(4-styrenesulfonate) (PEDOT : PSS) thin films using a slotdie coater for the applications of OLED lightings. It is demonstrated that the properties of slot-die coated PEDOT : PSS films are comparable with those of spin-coated ones. Namely, the average and peak-to-peak roughness of the slot-die coated 50-nm-thick PEDOT : PSS film are measured to be as low as 0.247 nm and 1.3 nm, respectively. Moreover, we have obtained excellent thickness uniformity (~1.91%). With the slot-die coated PEDOT : PSS films, we have fabricated green phosphorescent OLED devices. For comparison, we have also fabricated OLED devices with spin-coated PEDOT : PSS films. Both show almost no discrepancy in device performance. The power efficiency (25.4 lm/W) and emission uniformity (77%) of OLEDs with slot-die coated PEDOT : PSS films are shown to be slightly lower than those (27.3 lm/W, 80%) of OLEDs with spin-coated PEDOT : PSS films at the luminance of 1,000nit, increasing the feasibility of using a slot-die coating process for the fabrication of large-area OLED lighting sources at a competitive price.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.201.1-201.1
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• 2014

본 연구에서는 Slot die coating 공법으로 코팅된 Poly (3-4 ethylenedioxythiophene): Poly (styrenesulfonate) (PEDOT:PSS) 박막과 비정질 ITO 박막의 전기적, 광학적, 기계적 특성을 비교 평가하여 Slot die coating 공법으로 코팅된 PEDOT:PSS 박막의 유기태양전지의 전극으로서의 적용가능성을 확인하였다. 상업용 PEDOT:PSS 박막은 보통 280 Ohm/sq.의 면저항과 가시광 영역에서 약 80%의 광투과도를 나타내며, 비정질 ITO 박막과 유사한 전기적, 광학적 특성을 나타내었다. Slot die coating 공법을 통해 제작된 PEDOT:PSS 투명 전극과 비정질 ITO 투명 전극의 기판 휘어짐에 따른 전기적 안정성을 비교 평가하기 위해 25 mm에서 1 mm까지 radius 변화에 따른 저항의 변화를 측정하였다. 그 결과, 비정질 ITO 투명 전극 대비 PEDOT:PSS 투명 전극이 더 우수한 전기적 안정성을 나타냄을 확인하였다. 또한, 다양한 Bending test (Inner/Outer bending, Rolling, Stretching, Twisting) 를 통해 비정질 ITO 투명 전극 보다 Slot die coating 공법으로 코팅된 PEDOT:PSS 투명 전극의 우수한 기계적 특성을 확인하였다. 이를 바탕으로 Flexible 유기태양전지에의 적용 가능성을 알아보기 위해 Slot die coating 공법으로 코팅된 PEDOT:PSS 투명 전극과 비정질 ITO 투명 전극을 유기태양전지의 anode 층에 적용하여 각각 제작하고 그 특성을 평가하였다. 비정질 ITO 투명 박막을 적용한 유기태양전지 대비 Slot die coating 공법으로 코팅된 PEDOT:PSS 투명 박막으로 제작한 유기태양전지에서 더 높은 효율이 나타났으며, 이로써 Slot die coating 공법으로 코팅된 PEDOT:PSS 투명 전극의 Flexible 유기태양전지로써의 적용 가능성을 확인하였다.

• Applied Chemistry for Engineering
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• v.26 no.4
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• pp.458-462
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• 2015

It is essential to employ a binder to prepare transparent films from conductive polymer such as poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT/PSS). In this paper, poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP), and PSS were selected as a binder, and their effects were investigated. The formation of the film was found to be primarily dependent on the surface tension of coating solution including PEDOT/PSS and a binder. When PSS was used as a binder, the film was not formed. In case of using PVP, it was easily peeled off from the substrate. However, when using the PVA or the mixtures of PVA and PSS or PVA and PVP as a binder, films with good transparency and uniform surface resistances were produced. Based on adhesion and long-term stability tests, we concluded that the mixture of PVA and PSS is the best binder for preparing antistatic films of PEDOT/PSS.

• Current Photovoltaic Research
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• v.7 no.3
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• pp.61-64
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• 2019

In this study, we investigate organic-inorganic hybrid solar cells with a very simple three-layer structure (Al/n-Si/PEDOT:PSS). The performance of hybrid solar cells is optimized by controlling the sheet resistance and optical transmittance of the PEDOT:PSS layers. As the thickness of the PEDOT:PSS layer decreases, the optical absorption of the n-Si increases, which greatly improves the short-circuit current density ($J_{SC}$) of devices, but the increase in sheet resistance leads to a decrease in the open-circuit voltage ($V_{OC}$) and the fill factor (FF). The solar cell with the 180-nm thick PEDOT:PSS layer shows a highest efficiency of 8.45% ($V_{OC}$: 0.435 V, $J_{SC}$: $33.7mA/cm^2$, FF: 57.5%). Considering these results, it is expected that the optimizing process for the sheet resistance and transmittance of the PEDOT:PSS layer is essential for producing high-efficiency organic-inorganic hybrid solar cells and will serve as an important basis for achieving low-cost, high-efficiency solar cells.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.299-299
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• 2013

Indium Tin Oxide (ITO) has widely been used as a transparent conductive oxide (TCE) for photovoltaic devices. Lately, flexibility of ITO becomes an issue as demand of flexible device increases. Several scientists have tried to substitute ITO to different materials such as conductive polymer, graphene, CNT, and metal nanowire because of ITO brittleness. Among the substitute materials, PEDOT:PSS has mostly paid attention because PEDOT:PSS has excellent flexibility and good conductivity. The conductivity of PEDOT:PSS increases up to 1000 S/cm with additives such as DMSO, EG, sorbitol, and so on. In our research group, we introduce a conductive polymer PEDOT:PSS as a buffer layer to improve not only flexibility but also conductivity. As PEDOT:PSS layer forms beneath ITO thin film (20 nm), sheet resistance decreases from $230{\Omega}$/${\Box}$ to $85{\Omega}$/${\Box}$ and crack initiation decreases from 4.5 mm to 3.5 mm as well. We have fabricated organic photovoltaic device and power conversion efficiencies using conventional ITO electrode and ITO/PEDOT:PSS hybrid electrode. The photovoltaic property such as power conversion efficiency for ITO/PEDOT:PSS hybrid electrode is comparable to the value obtained using conventional ITO electrode on glass substrate.

• Fashion & Textile Research Journal
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• v.24 no.1
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• pp.146-155
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• 2022

We proposed a simple process of creating electroconductive textiles by using PEDOT:PSS(Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate))/non-oxidized graphene to coat polyamide or polyurethane knitted fabric for smart healthcare purposes. Electroconductive textiles were obtained through a coating process that used different amounts of PEDOT:PSS/non-oxidized graphene solutions on polyamide/polyurethane knitted fabric. Subsequently, the surface, electrical, chemical, weight change, and elongation properties were evaluated according to the ratio of PEDOT:PSS/non-oxidized graphene composite(1.3 wt%:1.0 wt%; 1.3 wt%:0.6 wt%; 1.3 wt%:0.3 wt%) and the number of applications(once, twice, or thrice). The specimens' surface morphology was observed by FE-SEM. Further, their chemical structures were characterized using FTIR and Raman spectroscopy. The electrical properties measurement (sheet resistance) of the specimens, which was conducted by four-point contacts, shows the increase in conductivity with non-oxidized graphene and the number of applications in the composite system. Moreover, a test of the fabrics' mechanical properties shows that PEDOT:PSS/non-oxidized graphene-treated fabrics exhibited less elongation and better ability to recover their original length than untreated samples. Furthermore, the PEDOT:PSS/non-oxidized graphene polyamide/polyurethane knitted fabric was tested by performing tensile operations 1,000 times with a tensile strength of 20%; Consequently, sensors maintained a constant resistance without noticeable damage. This indicates that PEDOT:PSS/non-oxidized graphene strain sensors have sufficient durability and conductivity to be used as smart wearable devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1003-1006
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• 2003

We have investigated the effect of hole-injection buffer layer and cathodes in organic light-emitting diodes u sing poly (3,4-ethylenedioxythiophene) : poly (stylenesulfonate) (PEDOT: PSS) in a device structure of $ITO/PEDOT:PSS/TPD/Alq_3/Cathode$. Polymer PEDOT:PSS buffer layer was made using spin casting method. Current-voltage, luminance-voltage characteristics and efficiency of device were measured at room temperature with a variation of cathode materials. The device with LiF/Al cathode shows an improvement of external quantum efficiency approximately by a factor of ten compared to that of Al cathode only device. Our observation shows that the energy barrier-height in cathode side is important in improving the efficiency of the organic light-emitting diodes.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.313-313
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• 2010

The performance of polymer photovoltaic cells based on blends of poly(3-hexylyhiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) is strongly influenced by blend composition and thickness. Polymer photovoltaic cells based on bulk-heterojunction have been fabricated with a structure of ITO/poly(3, 4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)-pentacene/poly (3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM)/Al. We have prepared PEDOT:PSS by dissolving pentacene in N-methylpyrrolidine (NMP) and mixing with PEDOT:PSS. Pentacene was added a maximum concentration of approximately 5.5mg to the PEDOT:PSS solution and sonicated for 10 min. Active layer (P3HT:PCBM) (1:1) was strongly influenced by PEDOT:PSS-pentacene. We have investigated the performance of photovoltaic device with different concentration of P3HT:PCBM (1:1) 2.0wt%, 2.2wt%, 2.4wt% and 2.6wt%, respectively. The photocurrent and power conversion efficiency (PCE) showed a maximum between 2.0wt% and 2.2wt% concentration of P3HT:PCBM. This implied that both morphology and electron transport properties of the layer influenced the performance of the present photovoltaic cells. As the concentration of P3HT:PCBM blends as an active layer was increased, the power conversion efficiency was decreased. P3HT:PCBM layer and PEDOT:PSS-pentacene layer were characterized by work function, UV-visible absorption, atomic force microscopy (AFM), X-ray diffraction (XRD) and scanning electron microscope (SEM).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.2
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• pp.121-125
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• 2014

In this research, nanocomposite layers consisting of poly (3,4,-ethylene dioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) and CuO nanoparticles were investigated as hole transport layers in organic solar cells based on poly (3-hexylthiophene) (P3HT) as the electron donor and (6.6) phenyl-C61-butyric acid methyl ester (PCBM) as the electron acceptor. The addition of CuO nanoparticles to PEDOT:PSS layer improved the solar cell performance with 0.5% CuO nanoparticle concentration. At optimized concentration, CuO mixed PEDOT:PSS films had good electrical ($4.131{\Omega}{\cdot}cm$) and optical (transmittance > 90%) properties for using hole transporting layer. We investigated that improved solar cell performance with CuO nanoparticles mixed PEDOT:PSS films.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2291-2296
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• 2013

An efficient carbon monoxide (CO) sensor was developed based on poly(3,4-ethylenedioxy)thiophenepoly(styrenesulfonate) (PEDOT:PSS) modified with a new pyrimidine-fused heterocyclic compound, bis(2-hydroxyphenyl)dihydropyrido[2,3-d:6,5-d]dipyrimidine-tetraone (B2HDDT). B2HDDT remains stable in the polymer matrix through interactions with functional groups of the polymer. It created prominent sites that captured CO gas, and the experimental parameters, including the amount of doped B2HDDT in the PEDOT:PSS film, were optimized. The sensor probe was also examined to verify its reliability for detecting CO in the presence of atmospheric gases in a discriminating manner. NMR, AFM, and FT-IR spectra were obtained to evaluate the structure and morphology of the B2HDDT-doped PEDOT:PSS (PEDOT:PSS/B2HDDT) film. The content of 35 vol % B2HDDT (7.0 mM) in PEDOT:PSS provided the largest response factor (${\Delta}R/R_o$) for the CO gas. The sensor response was reproducible, with a relative standard deviation < 5% (n = 5). The detection limit was determined to be $0.44{\pm}0.05$ vol %.