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Erratum to: Charge transfer in graphene/polymer interfaces for CO2 detection
Kim, Kihyeun,Son, Myungwoo,Pak, Yusin,Chee, Sang-Soo,Auxilia, Francis Malar,Lee, Byung-Kee,Lee, Sungeun,Kang, Sun Kil,Lee, Chaedeok,Lee, Jeong Soo,Kim, Ki Kang,Jang, Yun Hee,Lee, Byoung Hun,Jung, Gun- Springer-Verlag 2018 NANO RESEARCH Vol.11 No.7
Kim, Woochul,Park, Jiyoon,Kim, Hyeonghun,Pak, Yusin,Lee, Heon,Jung, Gun Young Elsevier 2017 ELECTROCHIMICA ACTA Vol.245 No.-
<P><B>Abstract</B></P> <P>Organic-inorganic hybrid perovskite solar cells (PSCs) have reached a power conversion efficiency of 22.1% in a short period (∼7 years), which has been obtainable in silicon-based solar cells for decades. The high power conversion efficiency and simple fabrication process render perovskite solar cells as potential future power generators, after overcoming the lack of long-term stability, for which the deposition of void-free and pore-filled perovskite films on mesoporous TiO<SUB>2</SUB> layers is the key pursuit. In this research, we developed a sequential dip-spin coating method in which the perovskite solution can easily infiltrate the pores within the TiO<SUB>2</SUB> nanoparticulate layer, and the resultant film has large crystalline grains without voids between them. As a result, a higher short circuit current is achieved owing to the large interfacial area of TiO<SUB>2</SUB>/perovskite, along with enhanced power conversion efficiency, compared to the conventional spin coating method. The as-made pore-filled and void-free perovskite film avoids intrinsic moisture and air and can effectively protect the diffusion of degradation factors into the perovskite film, which is advantageous for the long-term stability of PSCs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sequential dip-spin coating method is developed to coat a uniform perovskite film without voids. </LI> <LI> The dip-spin coated perovskite film increases the recombination resistance owing to complete pore-filling, enhancing the J<SUB>SC</SUB> and PCE. </LI> <LI> A void-free and pore-filled perovskite film with large grains (average 2.10μm) is achieved by the dip-spin coating. </LI> <LI> The pore-filled and void-free perovskite film fabricated via dip-spin coating prevents the diffusion. </LI> <LI> The cell fabricated via the dip-spin coating maintains 99% of their initial PCE after 35days of storage. </LI> </UL> </P>
Kim, Hyeonghun,Pak, Yusin,Jeong, Yeonggyo,Kim, Woochul,Kim, Jeongnam,Jung, Gun Young Elsevier 2018 Sensors and actuators. B Chemical Vol.262 No.-
<P><B>Abstract</B></P> <P>For monitoring H<SUB>2</SUB> concentrations in air, diverse resistive gas sensors have been demonstrated. In particular, Pd-decorated metal oxides have shown remarkable selectivity and sensing response for H<SUB>2</SUB> detection. In this work, H<SUB>2</SUB> sensing behavior of amorphous Pd layer covering ZnO nanorods (am-Pd/ZnO NRs) is investigated. This is the first report on the enhanced gas sensing performance attained by using an amorphous metal layer. The amorphous Pd layer is generated by reduction reaction with a strong reducing agent (NaBH<SUB>4</SUB>), and it covers the ZnO nanorods completely with a thickness of 2–5 nm. For comparison, crystalline Pd nanoparticles-decorated ZnO nanorods (c-Pd/ZnO NRs) are produced using a milder reducing agent like hydrazine. Comparing the c-Pd/ZnO NRs sensor and other previously reported hydrogen sensors based on the crystalline Pd and metal oxides, the am-Pd/ZnO NRs sensor exhibits a remarkable sensing response (12,400% at 2% H<SUB>2</SUB>). The enhancement is attributed to complete cover of the amorphous Pd layer on the ZnO NRs, inducing larger interfaces between the Pd and ZnO. In addition, the amorphous Pd layer prevents surface contamination of the ZnO NRs. Therefore, the am-Pd/ZnO NRs sensor maintains initial sensing performance even after 5 months.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Facile synthesis of ultrathin amorphous Pd layer (2–5 nm) on ZnO nanorods. </LI> <LI> Comparison of sensing behavior between amorphous and crystalline Pd-coated ZnO nanorods sensors. </LI> <LI> Demonstration of superior sensing response (12,400%) of amorphous Pd-coated ZnO nanorods sensors. </LI> <LI> High stability of amorphous Pd-coated ZnO nanorods sensors. </LI> </UL> </P>
Palladium-Decorated Hydrogen-Gas Sensors Using Periodically Aligned Graphene Nanoribbons
Pak, Yusin,Kim, Sang-Mook,Jeong, Huisu,Kang, Chang Goo,Park, Jung Su,Song, Hui,Lee, Ryeri,Myoung, NoSoung,Lee, Byoung Hun,Seo, Sunae,Kim, Jin Tae,Jung, Gun-Young American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.15
<P>Polymer residue-free graphene nanoribbons (GNRs) of 200 nm width at 1 μm pitch were periodically generated in an area of 1 cm<SUP>2</SUP> via laser interference lithography using a chromium interlayer prior to photoresist coating. High-quality GNRs were evidenced by atomic force microscopy, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy measurements. Palladium nanoparticles were then deposited on the GNRs as catalysts for sensing hydrogen gases, and the GNR array was utilized as an electrically conductive path with less electrical noise. The palladium-decorated GNR array exhibited a rectangular sensing curve with unprecedented rapid response and recovery properties: 90% response within 60 s at 1000 ppm and 80% recovery within 90 s in nitrogen ambient. In addition, reliable and repeatable sensing behaviors were revealed when the array was exposed to various gas concentrations even at 30 ppm.</P><P>A polymer residue-free graphene nanoribbon (GNR) array with a 200 nm line width at 1 μm pitch is fabricated via laser interference lithography by depositing a chromium interlayer prior to photoresist coating. The palladium-decorated GNR-array hydrogen-gas sensor exhibits reliable and repeatable behaviors as well as rapid response and recovery characteristics: 90% response within 60 s at 1000 ppm and 80% recovery within 90 s in nitrogen ambient.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-15/am503105s/production/images/medium/am-2014-03105s_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am503105s'>ACS Electronic Supporting Info</A></P>
자동차 페열회수장치 최적 설계를 위한 상변화물질 특성 평가
정유신(Yusin Jeong),우승철(Seungchul Woo),김웅일(Woongil Kim),김영근(Youngkun Kim),이기형(Kihyung Lee) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6
최근 배기규제가 강화됨에 따라 내연기관 자동차는 엔진의 열에너지 관리가 점차 중요해지고 있다. 전체 연료 에너지 중 엔진에서 약 75%의에너지가열에너지의 형태로 버려지므로 이 손실을 줄이는 것이 배기가스저감 및 연비향상에 매우 중요한 역할을 한다. 따라서 이러한 폐열을 이용한 차량용 폐열회수장치 개발은 엔진의 연비 및 배기과제를 해결할 수 있는 하나의 방법으로 주목을 받고 있는 실정이다. 자동차의 폐열을 회수할 수 있는 기술로는 열에너지를 저장한 후 에너지가 요구될 때 사용하는 축열시스템과 열에너지를 이용하여 동력으로 전환하는 방법, 열전소자를 이용하여 열에너지를 전기에너지로 변환하는 방법 등이 있다. 이 중 축열 시스템은 간단한 구조와 차량에 적용하기 쉽다는 장점 때문에 엔진 적용을 기대할 수 있는 기술이라고 말할 수 있다. 축열 시스템을 이용한 폐열 회수 장치를 엔진 냉간 시동시 웜업에 사용한다면 배기가스 저감 및 연비향상 효과를 기대할 수 있다. 본 연구에서는 폐열회수장치 적용을 위해, 선정된 상변화물질을 분석하고 축열 시스템에 대한 적합성을 평가하였다. 그 분석과 평가를 토대로 축열 효율을 최대화하기 위한 시스템을 설계하였다. 또한, 1D Simulation을 통해 폐열회수장치에 최적화된 열교환기 설계와 상변화 물질에 따른 성능을 평가하였다. 이러한 결과를 바탕으로 향후 실제 차량에 적용하여 자동차의 연비 향상 및 배기가스 저감 기술 개발에 활용하고자 한다.
Lee, Kwang‐,Ho,Kim, Sang‐,Mook,Jeong, Huisu,Pak, Yusin,Song, Hui,Park, Jeongpil,Lim, Keon‐,Hee,Kim, Jae‐,Hoon,Kim, Youn Sang,Ko, Heung Cho,Kwon, Il Keun,Jung, Gun‐,Young WILEY‐VCH Verlag 2013 ADVANCED MATERIALS Vol.25 No.23
<P><B>All‐solution‐processed transparent thin film transistors (TTFTs)</B> are demonstrated with silver grid source/drain electrodes, which are fabricated by printing and subsequent silver nanoparticles solution coating, which allows continuous processing without using high vacuum systems. The silver grid electrode shows a reasonable transmittance in visible range, moderate electrical conductance and mechanical strength. The TTFTs are employed to drive liquid crystal cells and demonstrate a successful switching operation.</P>