• 제목/요약/키워드: nanorod

검색결과 290건 처리시간 0.032초

ZnO 나노로드 배열에 의한 GaN기반 광다이오드의 광추출율 향상 (Improved Light Output of GaN-Based Light-Emitting Diodes with ZnO Nanorod Arrays)

  • 이삼동;김경국;박재철;김상우
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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    • pp.59-60
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    • 2008
  • GaN-based light-emitting diodes (LEDs) with ZnO nanorod arrays on a planar indium tin oxide (ITO) transparent electrode were demonstrated. ZnO nanorods were grown into aqueous solution at low temperature of $90^{\circ}C$. Under 20 mA current injection, the light output efficiency of the LED with ZnO nanorod arrays on ITO was remarkably increased by about 40 % of magnitude compared to the conventional LED with only planar ITO. The enhancement of light output by the ZnO nanorod arrays is due to the formation of side walls and a rough surface resulting in multiple photon scattering at the LED surface.

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가시광 수소생산용 CdSe/ZnO nanorod 투명전극 (CdSe Sensitized ZnO Nanorods on FTO Glass for Hydrogen Production under Visible Light Irradiation)

  • 김현;양비룡
    • 한국수소및신에너지학회논문집
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    • 제24권2호
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    • pp.107-112
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    • 2013
  • The ZnO is able to produce hydrogen from water however it can only absorb ultraviolet region due to its 3.37eV of wide band gap. Therefore efficiency of solar hydrogen production is low. In this work we report investigation results of improved visible light photo-catalytic properties of CdSe quantum dots(QDs) sensitized ZnO nanorod heterostructures. Hydrothermally vertically grown ZnO nanorod arrays on FTO glass were sensitized with CdSe by using SILAR(successive ionic layer adsorption and reaction) method. Morphology of grown ZnO and CdSe sensitized ZnO nanorods had been investigated by FE-SEM that shows length of $2.0{\mu}m$, diameter of 120~150nm nanorod respectively. Photocatalytic measurements revealed that heterostructured samples show improved photocurrent density under the visible light illumination. Improved visible light performance of the heterostructures is resulting from narrow band gap of the CdSe and its favorable conduction band positions relative to potentials of ZnO band and water redox reaction.

나노 ZnO 분말을 이용한 가스센서 제작 및 특성연구 (Characteristics and Preparation of Gas Sensor Using Nano-ZnO Powders)

  • 유일
    • 한국재료학회지
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    • 제25권6호
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    • pp.300-304
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    • 2015
  • Nanorod ZnO and spherical nano ZnO for gas sensors were prepared by hydrothermal reaction method and hydrazine method, respectively. The nano-ZnO gas sensors were fabricated by a screen printing method on alumina substrates. The gas sensing properties were investigated for hydrocarbon gas. The effects of Co concentration on the structural and morphological properties of the nano ZnO:Co were investigated by X-ray diffraction and scanning electron microscope (SEM), respectively. XRD patterns revealed that nanorod and spherical ZnO:Co with a wurtzite structure were grown with (100), (002), (101) peaks. The sensitivity of nanorod and spherical ZnO:Co sensors was measured for 5 ppm $CH_4$ and $CH_3CH_2CH_3$ gas at room temperature by comparing the resistance in air with that in target gases. The highest sensitivity to the $CH_4$ and $CH_3CH_2CH_3$ gas of spherical nano ZnO:Co sensors was observed at Co 6 wt%. The spherical nano ZnO:Co sensor exhibited a higher sensitivity to hydrocarbon gas than nanorod ZnO.

Post-Annealing Effects on Properties of ZnO Nanorods Grown on Au Seed Layers

  • Cho, Min-Young;Kim, Min-Su;Choi, Hyun-Young;Yim, Kwang-Gug;Leem, Jae-Young
    • Bulletin of the Korean Chemical Society
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    • 제32권3호
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    • pp.880-884
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    • 2011
  • ZnO nanorods were grown by hydrothermal method. Two kinds of seed layers, Au film and island seed layers were prepared to investigate the effect of seed layer on ZnO nanorods. The ZnO nanorod on Au island seed layer has more unifom diameter and higher density compared to that of ZnO nanorod on Au film seed layer. The ZnO nanorods on Au island seed layer were annealed at various temperatures ranging from 300 to $850^{\circ}C$. The pinholes at the surface of the ZnO nanorods is formed as the annealing temperature is increased. It is noted that the pyramid structure on the surface of ZnO nanorod is observed at $850^{\circ}C$. The intensity of ZnO (002) diffraction peak in X-ray diffraction pattern and intensity of near band edge emission (NBE) peak in photoluminescence (PL) are increased as the ZnO nanorods were annealed at the temperature of $300^{\circ}C$.

힘센서를 이용한 나노구조체의 인장물성 측정 (Measuring the Tensile Properties of the Nanostructure Using a Force Sensor)

  • 전상구;장훈식;권오헌;남승훈
    • 대한기계학회논문집A
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    • 제34권2호
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    • pp.211-217
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    • 2010
  • 다양한 분야에 활용이 가능한 나노소자의 개발과 나노소자의 수명 및 신뢰성을 결정하기 위해서 나노구조체의 역학물성 측정은 중요하다. 본 연구에서는 다중벽탄소나노튜브(MWCNT)와 산화아연나노막대(ZnO nanorod)의 인장시험을 전자주사현미경(SEM) 내부에서 수행하였다. 챔버내부에 구축된 나노조작기 앞에 힘센서가 장착되었고, 나노조작기는 조이스틱과 컴퓨터로 제어 가능하도록 설계되었다. 반으로 자른 투과전자현미경(TEM)그리드 위에 분산된 나노구조체는 전자주사를 통하여 힘센서와 고정된 후 인장시험이 수행되었다. 인장시험 후 TEM과 SEM을 통하여 파단면을 측정하였고 MWCNT와 ZnO nanorod의 탄성계수는 0.98TPa, 55.85GPa로 각각 측정되었다.

Heterojunction Quantum Dot Solar Cells Based on Vertically Growth TiO2 Anatase Nanorod Arrays with Improved Charge Collection Property

  • Chung, Hyun Suk;Han, Gill Sang;Park, So Yeon;Lee, Dong Geon;Jung, Hyun Suk
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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    • pp.466.2-466.2
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    • 2014
  • The Quantum dot (QD) solar cells have been under active research due to their high light harvesting efficiencies and low fabrication cost. In spite of these advantages, there have been some problems on the charge collection due to the limitation of the diffusion length. The modification of advanced nanostructure is capable of solving the charge collection problem by increasing diffusion length of electron. One dimensional nanomaterials such as nanorods, nanowires, and nanotubes may enhance charge collection efficiency in QD solar cells. In this study, we synthesized $TiO_2$ anatase nanorod arrays with length of 200 nm by two-step sol-gel method. The morphology and crystal structure for the nanorod were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The anatase nanorods are single-crystalline and possess preferred orientation along with (001) direction. The photovoltaic properties for the heterojunction structure QD solar cells based on the anatase nanorod were also characterized. Compared with conventional $TiO_2$ nanoparticle based QD solar cells, these nanostructure solar cells exhibited better charge collection properties due to long life time measured by transient open circuit studies. Our findings demonstrate that the single crystalline anatase nanorod arrays are promising charge transport semiconductors for heterojunction QD solar cells.

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마그넬리상 합성과 광전기화학셀 전극 응용 (Synthesis of Magneli Phases and Application to the Photoelectrochemical Electrode)

  • 박지환;;양하늘;홍순현;;김천중;김도진
    • 한국재료학회지
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    • 제28권5호
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    • pp.261-267
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    • 2018
  • Hydrothermal synthesis of highly crystalline $TiO_2$ nanorods is a well-developed technique and the nanorods have been widely used as the template for growth of various core-shell nanorod structures. Magneli/CdS core-shell nanorod structures are fabricated for the photoelectrochemical cell (PEC) electrode to achieve enhanced carrier transport along the metallic magneli phase nanorod template. However, the long and thin $TiO_2$ nanorods may form a high resistance path to the electrons transferred from the CdS layer. $TiO_2$ nanorods synthesized are reduced to magneli phases, $TixO_{2x-1}$, by heat treatment in a hydrogen environment. Two types of magneli phase nanorods of $Ti_4O_7$ and $Ti_3O_5$ are synthesized. Structural morphology and X-ray diffraction analyses are carried out. CdS nano-films are deposited on the magneli nanorods for the main light absorption layer to form a photoanode, and the PEC performance is measured under simulated sunlight irradiation and compared with the conventional $TiO_2/CdS$ core-shell nanorod electrode. A higher photocurrent is observed from the stand-alone $Ti_3O_5/CdS$ core-shell nanorod structure in which the nanorods are grown on both sides of the seed layer.

산화아연 나노막대가 내장된 아산화구리 박막 구조를 이용한 산화물 광양극 제작 및 광전기화학적 특성 (Fabrication and Photoelectrochemical Properties of an Oxide Photoanode with Zinc Oxide Nanorod Array Embedded in Cuprous Oxide Thin Film)

  • 민병국;김효진
    • 한국재료학회지
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    • 제29권3호
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    • pp.196-203
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    • 2019
  • We report on the fabrication and characterization of an oxide photoanode with a zinc oxide (ZnO) nanorod array embedded in cuprous oxide ($Cu_2O$) thin film, namely a $ZnO/Cu_2O$ oxide p-n heterostructure photoanode, for enhanced efficiency of visible light driven photoelectrochemical (PEC) water splitting. A vertically oriented n-type ZnO nanorod array is first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method and then a p-type $Cu_2O$ thin film is directly electrodeposited onto the vertically oriented ZnO nanorod array to form an oxide p-n heterostructure. The introduction of $Cu_2O$ layer produces a noticeable enhancement in the visible light absorption. From the observed PEC current density versus voltage (J-V) behavior under visible light illumination, the photoconversion efficiency of this $ZnO/Cu_2O$ p-n heterostructure photoanode is found to reach 0.39 %, which is seven times that of a pristine ZnO nanorod photoanode. In particular, a significant PEC performance is observed even at an applied bias of 0 V vs $Hg/Hg_2Cl_2$, which makes the device self-powered. The observed improvement in the PEC performance is attributed to some synergistic effect of the p-n bilayer heterostructure on the formation of a built-in potential including the light absorption and separation processes of photoinduced charge carriers, which provides a new avenue for preparing efficient photoanodes for PEC water splitting.

Synthetic Strategy and Optical Property Characterization of Complex Nanorods: Plasmon Wave Guide and Solar Cell

  • Park, Sung-Ho
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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    • pp.111-111
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    • 2012
  • In this talk, we represent a novel approach to investigating intra-nanorod surface plasmon coupling with control over block compositions. The multi-component rod-like nanostructures, which consist of optically active components (Au and Ag) and optically less active component (for example, Ni) in UV-vis-NIR spectral window, showed interesting optical response depending on each block length and the total length of the structure. By controlling the composition and relative lengths of the blocks that comprise these structures, we can tailor the overall optical properties. Depending on the relative fraction of Au and Ag blocks, the intensity of the transverse modes varied without noticeable peak shifts. However, the strong intraparticle surface plasmon coupling resulted in the collective appearance of longitudinal LSP modes, including higher-order modes. The experimental observations were confirmed by theoretical calculation, using a discrete dipole approximation method. In addition, we will briefly discuss how single nanorod solar cells can be synthesized by using by using electrochemical deposition and AAO hard templates.

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Development of Two-Component Nanorod Complex for Dual-Fluorescence Imaging and siRNA Delivery

  • Choi, Jin-Ha;Oh, Byung-Keun
    • Journal of Microbiology and Biotechnology
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    • 제24권9호
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    • pp.1291-1299
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    • 2014
  • Recently, multifunctional nanomaterials have been developed as nanotherapeutic agents for cellular imaging and targeted cancer treatment because of their ease of synthesis and low cytotoxicity. In this study, we developed a multifunctional, two-component nanorod consisting of gold (Au) and nickel (Ni) blocks that enables dual-fluorescence imaging and the targeted delivery of small interfering RNA (siRNA) to improve cancer treatment. Fluorescein isothiocyanate-labeled luteinizing hormone-releasing hormone (LHRH) peptides were attached to the surface of a Ni block via a histidine-tagged LHRH interaction to specifically bind to a breast cancer cell line, MCF-7. The Au block was modified with TAMRA-labeled thiolated siRNA in order to knock down the vascular endothelial growth factor protein to inhibit cancer growth. These two-component nanorods actively targeted and internalized into MCF-7 cells to induce apoptosis through RNA interference. This study demonstrates the feasibility of using two-component nanorods as a potential theranostic in breast cancer treatment, with capabilities in dual imaging and targeted gene delivery.