Highly Deformable and Transparent Optoelectronics Based on All-Conducting-Polymer Electrodes

Seyoung Kee(기세영) 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2

Flexible and transparent displays have been explored to create a new environment of human-machine interfaces. However, the fragile transparent conducting oxide and opaque metal electrodes used in current LED technologies cannot satisfy their desired mechanical and optical features. In this work, we report a demonstration of flexible and transparent polymer LEDs (FT-PLEDs) using solution-processable polymeric transparent electrodes. The resulting FT-PLEDs exhibit outstanding dual-side light-outcoupling performance with high optical transmittance of 75% at 550 nm wavelength and excellent mechanical durability under 9% bending strain and a repetitive bending 1,000 cycles. Moreover, ultrathin FT-PLEDs developed on 4-μm-thick plastic foils by all-solution processing show extremely deformable and completely foldable light-emitting functionality. Our approach is expected to open a new avenue for wearable transparent displays that could expand next-generation human-machine interfaces.

Modulation of electrostatic interaction in conducting polymer complexes using ionic liquids for highly ordered nanostructure

Seyoung Kee,Nara Kim,Bong Seong Kim,Seongjin Park,Yun Hee Jang,Seoung Ho Lee,Sooncheol Kwon,Jehan Kim,Junghwan Kim,Kwanghee Lee 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

Mechanical properties of LSCF (La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ)–GDC (Ce_0.9Gd_0.1O_2−δ) for oxygen transport membranes

Kim, Seyoung,Kim, Soo Hyun,Lee, Kee Sung,Yu, Ji Haeng,Seong, Young-Hoon,Han, In Sub Elsevier 2017 Ceramics international Vol.43 No.2

<P><B>Abstract</B></P> <P>In this study, for application in oxygen transport membranes, an LSCF (La<SUB>0.6</SUB>Sr<SUB>0.4</SUB>Co<SUB>0.2</SUB>Fe<SUB>0.8</SUB>O<SUB>3−δ</SUB>)–GDC (Ce<SUB>0.9</SUB>Gd<SUB>0.1</SUB>O<SUB>2−δ</SUB>) composite was manufactured, and its mechanical properties were studied. Generally, it is known that LSCF has a nonlinear modulus due to changes in its microstructure when a critical stress is loaded. To improve the mechanical properties of this material, which has a perovskite structure, a study was conducted to evaluate whether its properties change according to the rule of mixtures when it is formed into a composite with GDC. The results showed that the nonlinearity of the modulus of the composite for each specimen composition was largely reduced and stable under fatigue loading. The fracture toughness was superior to that of the LSCF (1.05MPam<SUP>1/2</SUP>) or GDC (1.28MPam<SUP>1/2</SUP>) monolithic materials when the composites (1.63MPam<SUP>1/2</SUP>) was manufactured. The mechanisms for these were explained by finite element analysis and the observation of crack propagation. It was also confirmed that when these composite materials are used for oxygen transport membranes, they show stable properties.</P>

Long-Term Stable Recombination Layer for Tandem Polymer Solar Cells Using Self-Doped Conducting Polymers

Lee, Jinho,Kang, Hongkyu,Kee, Seyoung,Lee, Seoung Ho,Jeong, Song Yi,Kim, Geunjin,Kim, Junghwan,Hong, Soonil,Back, Hyungcheol,Lee, Kwanghee American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.9

<P>Recently, the most efficient tandem polymer solar cells (PSCs) have used poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a p-type component of recombination layer (RL). However, its undesirable acidic nature, originating from insulating PSS, of PEDOT:PSS drastically reduces the lifetime of PSCs. Here, we demonstrate the efficient and stable tandem PSCs by introducing acid-free self-doped conducting polymer (SCP), combined with zinc oxide nanoparticles (ZnO NPs), as RL for PEDOT:PSS-free tandem PSCs. Moreover, we introduce an innovative and versatile nanocomposite system containing photoactive and p-type conjugated polyelectrolyte (p-CPE) into the tandem fabrication of an ideal self-organized recombination layer. In our new RL, highly conductive SCP facilitates charge transport and recombination process, and p-CPE helps to achieve nearly loss-free charge collection by increasing effective work function of indium tin oxide (ITO) and SCP. Because of the synergistic effect of extremely low electrical resistance, ohmic contact, and pH neutrality, tandem devices with our novel RL performed well, exhibiting a high power conversion efficiency of 10.2% and a prolonged lifetime. These findings provide a new insight for strategic design of RLs using SCPs to achieve efficient and stable tandem PSCs and enable us to review and extend the usefulness of SCPs in various electronics research fields.</P>

Highly Stretchable and Highly Conductive PEDOT:PSS/Ionic Liquid Composite Transparent Electrodes for Solution-Processed Stretchable Electronics

Teo, Mei Ying,Kim, Nara,Kee, Seyoung,Kim, Bong Seong,Kim, Geunjin,Hong, Soonil,Jung, Suhyun,Lee, Kwanghee American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.1

<P>Stretchable conductive materials have received great attention owing to their potential for realizing next generation stretchable electronics. However, the simultaneous achievement of excellent mechanical stretchability and high electrical conductivity as well as cost-effective fabrication has been a significant challenge. Here, we report a highly stretchable and highly conducting polymer that was obtained by incorporating an ionic liquid. When 1-ethyl-3-methylimidazolium tetracyanoborate (EMIM TCB) was added to an aqueous conducting polymer Solution of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), it was found that EMIM:TCB acts not only as a secondary dopant but also as a plasticizer for PEDOT:PSS, resulting in a high conductivity of >1000 S cm with stable performance at tensile strains up to 50% and even up to 180% in combination with the prestrained substrate technique. Consequently, by exploiting the additional benefits of high transparency and solution-processability of PEDOT:PSS, we were able to fabricate a highly stretchable, semitransparent, and wholly solution processed alternating current electroluminescent device with unimpaired performance at 50% strain by using PEDOT:PSS/EMIM TCB composite films as both bottom and top electrodes.</P>

Highly Conductive All-Plastic Electrodes Fabricated Using a Novel Chemically Controlled Transfer-Printing Method

Nara KIM,Hongkyu KANG,Jong-Hoon LEE,Seyoung KEE,Seoung Ho LEE,Kwanghee LEE 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

Self-assembly of interfacial and photoactive layers via one-step solution processing for efficient inverted organic solar cells

Kang, Hongkyu,Lee, Jinho,Jung, Suhyun,Yu, Kilho,Kwon, Sooncheol,Hong, Soonil,Kee, Seyoung,Lee, Seongyu,Kim, Dongwon,Lee, Kwanghee The Royal Society of Chemistry 2013 Nanoscale Vol.5 No.23

<P>Vertically self-assembled bilayers with an interfacial bottom layer and a photoactive top layer are demonstrated via a single coating step of a blend composed of an amine-containing nonconjugated polyelectrolyte (NPE) and an organic electron donor-acceptor bulk heterojunction composite. The self-assembled NPE layer reduces the work function of an indium tin oxide (ITO) cathode, which leads to efficient inverted organic solar cells without any additional interface engineering of the ITO.</P>

SiC_f-SiC 복합재료의 내환경 코팅 및 열, 기계적 내구성 평가

채연화 ( Yeon-hwa Chae ),문흥수 ( Heung Soo Moon ),김세영 ( Seyoung Kim ),우상국 ( Sang Kuk Woo ),박지연 ( Ji-yeon Park ),이기성 ( Kee Sung Lee ) 한국복합재료학회 2017 Composites research Vol.30 No.2

본 논문에서는 탄화규소 섬유강화 탄화규소 복합재료에 내환경 코팅을 수행한 후, 열·기계적 특성평가에 대한 연구를 수행하였다. 초기분말은 성형공정도중 흐름성을 좋게 하기 위해 분무건조법으로 구형의 분말을 제조하였다. 내환경 코팅재는 복합재료가 산화되거나 고온 수증기와 반응하는 것을 방지하기 위해 행하여 지는데, 본 연구에서는 액상침투법(LSI)으로 제조한 복합재에 실리콘으로 본드코팅을 하고 그 위에 대기플라즈마용사법으로 뮬라이트(mullite)와 무게비로 12% 이터븀 실리케이트(ytterbium silicate)가 혼합된 복합재를 코팅하였다. 대기플라즈마 코팅공정 시 성형변수로서 분무거리를 100, 120 그리고 140 mm로 변화시켰다. 그 후 1100oC의 온도에서 100시간동안 유지하는 실험과 1200oC의 온도에서 열충격을 가하는 싸이클을 3000회 반복하였다. 열내구성 시험동안 계면 박리는 일어나지 않았지만, 현저한 균열들이 코팅층 내에서 발견되었다. 균열밀도와 균열의 길이는 코팅도중의 분무거리에 의존하여 변화하였다. 열 내구성 시험 후, 압흔 시험을 통해 기계적 열화거동을 분석하였는데, 시험의 방식이나 조건들이 하중-변위 곡선의 거동에 영향을 주었다. This study investigates thermal and mechanical characterization of environmental barrier coating on the SiC_f-SiC composites. The spherical environmental barrier coating (EBC) powders are prepared using a spray drying process for flowing easily during coating process. The powders consisting of mullite and 12 wt% of Ytterbium silicate are air plasma sprayed on the Si bondcoat on the LSI SiC fiber reinforced SiC composite substrate for protecting the composites from oxidation and water vapor reaction. We vary the process parameter of spray distance during air plasma spray of powders, 100, 120 and 140 mm. After that, we performed the thermal durability tests by thermal annealing test at 1100oC for 100hr and thermal shock test from 1200oC for 3000 cycles. As a result, the interface delamination of EBC never occur during thermal durability tests while stable cracks are prominent on the coating layer. The crack density and crack length depend on the spray distance during coating. The post indentation test indicates thermal tests influence on the indentation load-displacement mechanical behavior.

수면무호흡증과 단순 코골이 환자의 증상과 질환 인식도 비교

이세영,강재명,조윤수,윤현진,김지언,신승헌,박기형,김선태,강승걸,Lee, Seyoung,Kang, Jae Myeong,Cho, Yoon-Soo,Yoon, Hyun Jin,Kim, Ji-Eun,Shin, Seung-Heon,Park, Kee Hyung,Kim, Seon Tae,Kang, Seung-Gul 대한수면의학회 2016 수면·정신생리 Vol.23 No.1

목 적 : 폐쇄성 수면무호흡증 (obstructive sleep apnea, OSA)은 비록 그 진단율이 낮지만 개인의 건강에 미칠 수 있는 위험은 상당하다. 그러나 OSA 환자가 실제 증상을 느끼는 정도는 예상보다 적으며, 질병의 심한 정도와 상관이 없는 경우가 많다. 이 연구는 OSA군과 단순코골이군 사이의 OSA 증상 인식 정도를 비교하기 위해 시행되었다. 방 법 : 임상적으로 OSA가 의심되는 282명의 피험자들이 연구에 포함되었다. 모든 피험자들은 수면다원검사를 받았고, 무호흡저호흡지수(apnea-hypopnea index, AHI)에 따라 5 이상이면 OSA군, 5 미만인 경우는 단순코골이군으로 분류되었다. 모든 피험자와 그 배우자(또는 같이 자는 사람)에 대하여 수면 장애와 질병의 인식도에 대한 설문조사를 수행하였다. 결 과 : OSA군에 비해서 단순코골이군이 코골이, 불규칙적 호흡, 무호흡 등의 수면 장애 증상을 더 잘 인식하였다. 또한 배우자(또는 같이 자는 사람)의 경우도 단순코골이군에서 피험자의 증상을 더욱 잘 인지하였다. 그렇지만 증상을 느낀 기간은 OSA군에서 유의하게 더 길었다. 상관분석에서 OSA의 증상 인식 정도는 나이, AHI, BMI, ESS 점수와 음의 상관관계를 보였다. 수면 설문과 수면다원검사 결과 중에서 오직 피츠버그수면질평가척도(Pittsburgh Sleep Quality Index)만이 OSA의 증상 인식도와 양의 상관관계를 보였다. 또한 치료 방법에 있어서 양압기, 구강내 장치에 대해 알고 있는 피험자의 비율과 선호도가 낮게 나타났다. 결 론 : 본 연구 결과에서 단순코골이 환자가 OSA 환자보다 수면 장애를 더 잘 인식하였다. AHI가 높을수록 오히려 환자의 증상에 대한 인식은 낮아졌다. Background and Objectives: Obstructive sleep apnea (OSA) is often undiagnosed but is an important risk factor affecting the health of an individual. The level of awareness of the illness among patients with OSA is low and is not correlated with severity of the illness. This study was conducted to compare awareness of OSA symptoms and illness between patients with OSA and simple snorers. Materials and Methods: Two hundred eighty-two patients who were suspected of having OSA participated in this study. All subjects underwent overnight polysomnography. Those with an apnea-hypopnea index (AHI) ${\geq}5$ were classified as the OSA group, while those with an AHI < 5 were classified as the simple snoring group. A sleep questionnaire, which included items on awareness of the illness, OSA, and sleep symptoms, was administered to all subjects and their bed-partners. Results: Simple snorers were much more aware of their symptoms such as snoring, irregular breathing, and apnea than were patients with OSA. Bed-partners of simple snorers were also more aware of the participants' sleep symptoms than were partners of patients with OSA. However, the duration of OSA symptoms was longer in the OSA group. In the correlation analysis, the level of awareness of OSA symptoms was negatively correlated with AHI, age, body mass index, and Epworth Sleepiness Scale score. Among the sleep questionnaire and polysomnography results, only Pittsburgh Sleep Quality Index was positively correlated with level of awareness of OSA symptoms. The minority of the respondents had heard about the treatment methods of continuous positive airway pressure and oral appliance and preferred them as treatment options. Conclusion: This study suggests that simple snorers are more aware of their symptoms than are patients with OSA. A higher severity of OSA, represented by a higher AHI, is correlated with lower awareness of one's OSA symptoms.