Fine-Tunable Absorption of Uniformly Aligned Polyurea Thin Films for Optical Filters Using Sequentially Self-Limited Molecular Layer Deposition

Park, Yi-Seul,Choi, Sung-Eun,Kim, Hyein,Lee, Jin Seok American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.18

<P>Development of methods enabling the preparation of uniformly aligned polymer thin films at the molecular level is a prerequisite for realizing their optoelectronic characteristics as innovative materials; however, these methods often involve a compromise between scalability and accuracy. In this study, we have grown uniformly aligned polyurea thin films on a SiO2 substrate using molecular layer deposition (MLD) based on sequential and self-limiting surface reactions. By integrating plane polarized Fourier-transform infrared, Raman spectroscopic tools, and density functional theory calculations, we demonstrated the uniform alignment of polyurea MLD films. Furthermore, the selective-wavelength absorption characteristics of thickness controlled MLD films were investigated by integrating optical measurements and finite-difference time-domain simulations of reflection spectra, resulting from their thickness-dependent fine resonance with photons, which could be used as color filters in optoelectronics.</P>

Control over Alignment and Growth Kinetics of Si Nanowires through Surface Fluctuation of Liquid Precursor

Park, Yi-Seul,Jung, Da Hee,Lee, Jin Seok American Chemical Society 2016 Crystal Growth & Design Vol.16 No.12

<P>Control over alignment and growth kinetics of vertically aligned Si nanowire (v-SiNW) arrays, which were grown using chemical vapor deposition (CVD) via a metal catalyst-assisted vapor liquid solid (VLS) mechanism, was demonstrated by introducing a homemade bubbler system containing a SiCl4 solution as the Si precursor. Careful control over the bubbler afforded different amounts of SiCl4 supplied to the reactor. By varying the dipping depth (Dd) and tilting angle (Ta) of the bubbler, the SiCl4 precursor concentration would fluctuate to different degrees. The different SiCl4 concentrations afforded the fine-tuning of v-SiNW array properties like alignment and growth kinetics. The degree of alignment of v-SiNWs could be increased with large amounts of SiCl4, which was caused by slight shallow depth or gentle tilting of the SiCl4 solution in the bubbler due to an increasing degree of fluctuation and fluctuation area. The ability to control alignment and growth kinetics of v-SiNW arrays could be employed in advanced nanoelectronic devices.</P>

Anisotropic Silicification of Nanostructured Surfaces by Local Liquid-Phase Deposition

Park, Yi-Seul,Kim, Gyuri,Lee, Jin Seok American Chemical Society 2019 Langmuir Vol.35 No.39

<P>Exploration of the bioinspired silicification of artificial scaffolds is crucial to understanding and engineering the hierarchically complex and elaborate three-dimensional (3D) frustules of diatoms, which have high porosity and mechanical stability with related gas diffusion and storage properties. Herein, we report on the bioinspired silicification of the nanostructured surfaces of hexagonally close-packed silica bead (hc-SB) arrays using a liquid-phase deposition (LPD) method. This process, governed by the kinetics of silicification, was controlled using the concentration of the reactants and the reaction temperature and monitored in real time using a quartz-crystal microbalance, which allowed the investigation of the silicification on the surface during the LPD reaction. These heterogeneous LPD reactions on hc-SB arrays were optimized to mimic natural 3D hierarchical structures. Anisotropic silicification of the nanostructures occurred owing to differences in the energy and local concentration of silicic acid on the nanostructured surface. A 3D hierarchical pore network was realized via a heterogeneous LPD reaction by controlling the size, location, and arrangement of the SBs. We believe that our silicification process on nanostructured surfaces can lead to great improvements in the bioinspired morphogenesis-based engineering of 3D hierarchical structures.</P> [FIG OMISSION]</BR>

Synthesis of single-crystalline topological insulator Bi2Se3 nanomaterials with various morphologies

Park, Yi-Seul,Lee, Jin Seok Springer-Verlag 2014 JOURNAL OF NANOPARTICLE RESEARCH Vol.16 No.2

Morphology Control of Single Crystalline Rutile TiO_2 Nanowires

Yi-Seul Park,이진석 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.10

Nano-scaled metal oxides have been attractive materials for sensors, photocatalysis, and dye-sensitization for solar cells. We report the controlled synthesis and characterization of single crystalline TiO_2 nanowires via a catalyst-assisted vapor-liquid-solid (VLS) and vapor-solid (VS) growth mechanism during TiO powder evaporation. Scanning electron microscope (SEM) and transmission electron microscope (TEM) studies show that as grown TiO_2 materials are one-dimensional (1D) nano-structures with a single crystalline rutile phase. Also, energy-dispersive X-ray (EDX) spectroscopy indicates the presence of both Ti and O with a Ti/O atomic ratio of 1 to 2. Various morphologies of single crystalline TiO_2 nano-structures are realized by controlling the growth temperature and flow rate of carrier gas. Large amount of reactant evaporated at high temperature and high flow rate is crucial to the morphology change of TiO_2 nanowire.

Intramolecular and Intermolecular Interactions in Hybrid Organic–Inorganic Alucone Films Grown by Molecular Layer Deposition

Park, Yi-Seul,Kim, Hyein,Cho, Boram,Lee, Chaeyun,Choi, Sung-Eun,Sung, Myung Mo,Lee, Jin Seok American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.27

<P>Investigation of molecular interactions in polymeric films is crucial for understanding and engineering multiscale physical phenomena correlated to device function and performance, but this often involves a compromise between theoretical and experimental data, because of poor film uniformity. Here, we report the intramolecular and intermolecular interactions inside the ultrathin and conformal hybrid organic inorganic alucone films grown by molecular layer deposition, based on sequential and self-limiting surface reactions. Varying the carbon chain length of organic precursors, which affects their molecular flexibility, caused intramolecular interactions such as double reactions by bending of the molecular backbone, resulting in formation of hole vacancies in the films. Furthermore, intermolecular interactions in alucone polymeric films are dependent on the thermal kinetics of molecules, leading to binding failures and cross -linking at low and high growth temperatures, respectively. We illustrate these key interactions and identify molecular geometries and potential energies by density functional theory calculations.</P>

Annealed Au-Assisted Epitaxial Growth of Si Nanowires: Control of Alignment and Density

Park, Yi-Seul,Jung, Da Hee,Kim, Hyun Ji,Lee, Jin Seok American Chemical Society 2015 Langmuir Vol.31 No.14

<P>The epitaxial growth of 1D nanostructures is of particular interest for future nanoelectronic devices such as vertical field-effect transistors because it directly influences transistor densities and 3D logic or memory architectures. Silicon nanowires (SiNWs) are a particularly important 1D nanomaterial because they possess excellent electronic and optical properties. What is more, the scalable fabrication of vertically aligned SiNW arrays presents an opportunity for improved device applications if suitable properties can be achieved through controlling the alignment and density of SiNWs, yet this is something that has not been reported in the case of SiNWs synthesized from Au films. This work therefore explores the controllable synthesis of vertically aligned SiNWs through the introduction of an annealing process prior to growth via a Au-catalyzed vapor–liquid–solid mechanism. The epitaxial growth of SiNWs was demonstrated to be achievable using SiCl<SUB>4</SUB> as the Si precursor in chemical vapor deposition, whereas the alignment and density of the SiNWs could be controlled by manipulating the annealing time during the formation of Au nanoparticles (AuNPs) from Au films. During the annealing process, gold silicide was observed to form on the interface of the liquid-phase AuNPs, depending on the size of the AuNPs and the annealing time. This work therefore makes a valuable contribution to improving nanowire-based engineering by controlling its alignment and density as well as providing greater insight into the epitaxial growth of 1D nanostructures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2015/langd5.2015.31.issue-14/la503453b/production/images/medium/la-2014-03453b_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la503453b'>ACS Electronic Supporting Info</A></P>

Morphology Control of Single Crystalline Rutile TiO₂ Nanowires

Park, Yi-Seul,Lee, Jin-Seok Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.10

Nano-scaled metal oxides have been attractive materials for sensors, photocatalysis, and dye-sensitization for solar cells. We report the controlled synthesis and characterization of single crystalline $TiO_2$ nanowires via a catalyst-assisted vapor-liquid-solid (VLS) and vapor-solid (VS) growth mechanism during TiO powder evaporation. Scanning electron microscope (SEM) and transmission electron microscope (TEM) studies show that as grown $TiO_2$ materials are one-dimensional (1D) nano-structures with a single crystalline rutile phase. Also, energy-dispersive X-ray (EDX) spectroscopy indicates the presence of both Ti and O with a Ti/O atomic ratio of 1 to 2. Various morphologies of single crystalline $TiO_2$ nano-structures are realized by controlling the growth temperature and flow rate of carrier gas. Large amount of reactant evaporated at high temperature and high flow rate is crucial to the morphology change of $TiO_2$ nanowire.

대각보강된 연결보의 비선형 모델링파라메터 제안

박이슬(Park, Yi Seul),한상환(Han, Sang Whan) 한국콘크리트학회 2019 한국콘크리트학회 학술대회 논문집 Vol.31 No.2

17세기 후반~19세기 중국·일본 靑畫白磁의 특징 및 유입 양상 -市廛行廊 및 주변 유적 출토품을 중심으로-

박이슬 ( Park Yi Seul ) 단국사학회 2022 史學志 Vol.62 No.-

본 글에서는 17세기 후반∼19세기 시전행랑(市廛行廊) 및 주변 유적에서 출토된 중국과 일본 청화백자(靑畫白磁)를 중심으로 그 특징을 분석하여 각 나라에 대한 생산지 검토 그리고 유입 과정을 살펴보았다. 중국 원대(元代)시기에 처음으로 제작된 청화백자는 조선 전기부터 꾸준히 왕실과 사대부에서 선호되었다. 일본 청화백자는 개항 이후 본격적으로 조선으로 유입되었는데 청화백자의 질이 정교하고 문양이 화려해 수요가 높았다. 이러한 중국과 일본의 청화백자는 주로 조선 시대 유통처이자 소비처였던 시전(市廛)에서 취급되었다. 시전 및 주변 유적에 대한 발굴조사를 통해 외산 청화백자를 분석해 본 결과, 중국 청화백자는 17세기∼18세기 전반에 해당하는 Ⅳ층에서 많이 수습되었다. 기형적 특징은 발·잔·접시 모두 구연부(口緣部)에서 동체 하단부까지 사선형으로 내려가다 저부에서 완만한 곡선으로 마무리된다. 굽은 대체로 수직굽과 역사다리형굽으로 접지면을 예리하게 마무리하였다. 문양은 대표적으로 초화문(草花文)·화문(花文)·영지초화문(靈芝草花文)이 나타난다. 굽 안바닥에 관지(款識)와 특정한 작방(作房)을 나타낸 부호가 시문된 경우도 있다. 중국 청화백자의 특징을 종합적으로 살펴본 결과 대부분 명·청대 경덕진 민요에서 제작된 것들이다. 다음으로 일본 청화백자는 주로 19세기 이후에 해당하는 Ⅱ층에서만 확인된다. 기형적 특징은 우선 발은 기벽이 두껍고 몸체가 크다. 당시 조선의 관요였던 광주 분원리에서 제작된 것과 비슷하다. 이와 대조적으로 잔과 접시는 기측선의 형태가 사선형을 이루며 기벽이 얇다. 굽의 형태는 발·잔·접시 모두 접지면을 여러 번 깎아 단정하게 마무리한 수직굽과 역사 다리형굽이다. 문양은 율문(栗文)·초화문·수복문(壽福文) 등이 있다. 일본청화백자에도 굽 안바닥에 제작지, 생산지 그리고 장인의 이름을 새긴 것이 발견된다. 또한 전사지(轉寫紙)를 이용하여 문양을 시문하는 스텐실(stencil) 기법이 확인되었다. 일본 청화백자는 굽 안쪽에 시문된 명문을 통해 개항 이후부터 본격적으로 유입되고 있음을 알 수 있다. 이러한 외산자기(外産磁器)는 초기에 연행을 통해 조선으로 유입되었고, 이후 공무역, 사무역, 밀무역 등 다양한 형태로 공급이 이루어졌다. 중국과 일본의 청화백자의 수요 증가는 북학파(北學派)의 수입 청화백자 긍정론에 많은 영향을 받았으며, 조선후기 상품화폐경제가 발달하게 되면서 형성된 부농층이라는 새로운 신분계층으로부터 발생하였다. 이들은 고급기명으로 인식된 청화백자에 주목하였고, 청화백자의 수요가 늘어날수록 이에 상응하여 수입량도 증가하게 된 것이다. 영·정조시기에는 무분별한 청화백자의 사용을 막기 위해 왕실에서 중국과 일본의 청화백자 등 고급기명의 사용을 금지할 정도로 조선 사회에서는 청화백자에 대한 선호가 높았다. 그러나 이러한 금지령은 잘 지켜지지 않았고 시전 및 주변 유적에서 출토된 중국과 일본의 청화백자의 수량을 통해 오히려 수입이 이전보다 증가하였음을 알 수 있다. In this article, Chinese and Japanese blue and white porcelain excavated from Sijeon and surrounding ruins from the late 17th to the 19th century were analyzed for their characteristics, and the production area for each country was reviewed and the introduction process was examined. Blue and white porcelain, which was first produced during the Yuan Dynasty in China, has been consistently favored by the royal family and the nobility since the early Joseon Dynasty. Japanese blue and white porcelain was introduced to Joseon in earnest after the opening of the port, and the demand for blue and white porcelain was high because of its sophisticated quality and splendid patterns. These Chinese and Japanese blue and white porcelains were mainly handled in Sijeon, which was a distribution and consumption center in the Joseon Dynasty. As a result of analyzing foreign-made blue and white porcelain through excavation of Sijeon and surrounding ruins, many Chinese blue and white porcelains were recovered from the 17th to the first half of the 18th century in the IV layer. The deformed feature is that both bowl, glasses, and plates go down obliquely from the mouth to the lower part of the fuselage and finish with a gentle curve at the bottom. The heel has a sharp finish on the contact surface with a generally vertical heel and an inverted bridge heel. As for the patterns, there is a flower pattern, a flower pattern, and a Lingzhi-Caohua pattern. In some cases, the inner bottom of the heel is engraved with signs indicating the official position and a specific functioning room. As a result of comprehensively examining the characteristics of Chinese blue and white porcelain, most of them were produced in Jingdezhen(景德鎭) folk songs during the Ming and Qing Dynasties. Next, Japanese blue and white porcelain is found only in layer II, which is mainly from the 19th century onwards. The deformity characteristics are, first of all, the bowl are thick and the body is large. It is similar to the one made in Bunwon-ri, Gwangju, which was the royal kilns of the Joseon Dynasty at the time. In contrast, cups and plates have oblique lines and thin walls. The shape of the heel is a vertical heel and an inverted leg-shaped heel, which are neatly finished by cutting the contact surface several times for all of the bowl, cups, and plates. The patterns include chestnut design, a flower pattern, and Su-bok(壽福). Japanese blue and white porcelains are also found to have the name of the manufacturer, the place of production, and the craftsman engraved on the inside of the heel. In addition, the stencil technique of applying patterns using transfer paper was confirmed. It can be seen that Japanese blue and white porcelain has been introduced in earnest since the opening of the port through the inscription on the inside of the heel. These foreign-made porcelains were introduced into Joseon through Yeon-haeng(燕行) in the early days, and later supplied in various forms such as public trade, private trade, and smuggling. The increase in demand for blue and white porcelain in China and Japan was greatly influenced by the positive theory of imported blue and white porcelain by the Bug-Hag School(北學派), and arose from a new social class called the wealthy peasants, which was formed as the commodity currency economy developed in the late Joseon Dynasty. They paid attention to blue and white porcelain, which was recognized as a high-class vessel, and as the demand for blue and white porcelain increased, the amount of imports increased correspondingly. During the reigns of King Yeongjo and King Jeongjo, preference for blue and white porcelain was so high in Joseon society that the royal family banned the use of high-end vessels such as Chinese and Japanese blue and white porcelain to prevent the indiscriminate use of blue and white porcelain. However, these prohibitions were not well followed, and the number of Chinese and Japanese blue and white porcelain excavated from Sijeon and surrounding ruins indicates that imports actually increased compared to before.