• 센서학회지
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• 제31권4호
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• pp.249-254
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• 2022

To achieve high-performance colloidal quantum dot light-emitting diodes (QD-LEDs), the use of a densely packed QD film is crucial to prevent the formation of leakage current pathways and increase in interface resistance. Spin coating is the most common method to deposit QDs; however, this method often produces pinholes that can act as short-circuit paths within devices. Since state-of-the-art QD-LEDs typically employ mono- or bi-layer QDs as an emissive layer because of their low conductivities, the use of a densely packed and pinhole-free QD film is essential. Herein, we introduce the Langmuir-Blodgett (LB) technique as a deposition method for the fabricate densely packed QD films in QD-LEDs. The LB technique successfully transfers a highly dense monolayer of QDs onto the substrate, and multilayer deposition is performed by repeating the transfer process. To validate the comparability of the LB technique with the standard QD-LED fabrication process, we fabricate and compare the performance of LB-based QD-LEDs to that of the spin-coating-based device. Owing to the non-destructiveness of the LB technique, the electroluminescence efficiency of the LB-based QD-LEDs is similar to that of the standard spin coating-based device. Thus, the LB technique is promising for use in optoelectronic applications.

• 전자공학회논문지 IE
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• 제43권4호
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• pp.99-104
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• 2006

전기 전자 소자를 제작하는 방법으로 Langmuir-Boldgett(LB)법이 많은 관심을 받고 있다. 수면위에 형성된 단분자막을 압축 또는 확장하면, 분자가 배향하는 과정에서 맥스웰 변위전류(MDC)가 흐른다. MDC는 전속밀도의 변화에 기인해서 흐르므로 MDC를 측정하는 것에 의해 분자의 동적 거동 관찰할 수 있다. 단분자막을 압축하는 속도와 분자면적은 서로 선형적인 관계를 갖고 있다. 본 연구에서는 압축속도를 30, 40, 50mm/min으로 달리하여 단분자막의 동적 거동을 관찰하였으며 LB법을 이용하여 Arachidic acid 단분자를 slide glass 위에 Y-type으로 9$\sim$21층의 다층막을 누적하여 Au/Arachidic acid/Al 소자를 제작하였다. 또한 Metal-Insulator-Metal(MIM) 소자의 I-V 특성을 측정하여 전극간의 거리가 커질수록 절연특성이 좋아짐을 확인하였다.

• 한국전기전자재료학회논문지
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• 제14권9호
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• pp.757-761
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• 2001

We studied emitting properties of organic electroluminescent devices fabricated using the spin-coating and Langmuir-Blodgett(LB) technique. The LB technique has the advantage of precise control of the thickness better than spin-coating method. LB monolayer of poly(3-hexylthiophene)(P3HT) was deposited 27 layers onto the indium-tin-oxide(ITO) substrate as Y-type films by the vertical dipping method. In the absorption spectra, the λ$\_$max/ of P3HT-AA LB films and of spin-coating films showed about at 510, 545 and 590 nm corresponding to 2.43, 2.28, 2.10eV. And we observed that the turn-on voltage of devices deposited by LB method(10V) was higher than that of spin-coating method(8.5V) in voltage-current-luminance characteristic. In the logV-logJ characteristics of ITO/P3HT-AA LB/Al device, we confirmed that El device fabricated by LB method follows three conduction mechanisms: ohmic, space-charge-limited current(SCLC) conduction and trapped-carrier-limited space-charge current(TCLC) conduction.

• KSBB Journal
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• 제10권1호
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• pp.105-112
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• 1995

본 연구에서는 LB기법에 의하여 분자수준으로 고 정화된 효소를 이용하여 에탄올의 양을 측정하는 광섬유 바이오센서가 개발되 었다. ADH는 arachidic acid의 단분자막에 LB기법으로 고정화된다. 센서의 출력신호를 분석하기 위하여 고정화된 ADH의 효소 반응은 ordered multisubstrate mechanism을 이용 하여 검토되었다. 광학 측정 시스템이 제시되었으며, 센서의 출력신호는 에단올의 농도에 비례하여 증가 하며 LB막에 누적된 누적충수와 관련이 있음을 알 수 있었다. LB막의 누적된 누적충수를 20충으로 증가하면 센서의 신호출력 범위가 확장되어 45mM의 고농도 에탄올도 측정할 수 있었다. 순수지질의 단 분자막과 효소가 흡착된 지질의 단분자막의 $\pi$-Aisotherm은 중성의 subphase에서 각기 다른 전하를 띠는 세 가지 종류의 지질에 대하여 조사되었다. ADH의 흡착도가 가장 우수한 지질은 arachidic a acid이며 이는 중성의 sub phase에서 양의 전하를 띠는 ADH 분자와 읍극의 전하를 띠는 arachidic a acid 분자 사이에 작용하는 정전기력에 기인한 것이다.

• 한국응용과학기술학회지
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• 제23권2호
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• pp.137-146
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• 2006

We investigated the electrochemical properties for Langmuir-Blodgett (LB) films mixed with fatty acid (8A5H) and phospholipid (DLPE, DMPC, and DPPA). LB films of 8A5H monolayer and 8A5H-phospholipid mixture were deposited using the Langmuir-Blodgett method on the indium tin oxide(ITO) glass. The electrochemical properties measured using cyclic voltammetry with three-electrode system, an Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode at various concentrations(0.1, 0.5, and 1.0 mol/L) of $NaClO_4$ solution. A measuring range was reduced from initial potential to -1350 mV, continuously oxidized to 1650 mV and measured to the initial point. The scan rate was 50, 100, 150 and 200 mV/s, respectively. As a result, LB films of fatty acid and phospholipid (8A5H/DLPE and DPPA) appeared irreversible process were caused by only the reduction current from the cyclic voltammogram and LB film of 8A5H-DMPC mixture was found to be caused by a reversible oxidation-reduction process.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.820-825
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• 1998

We deposited stearic acid LB films by using Langmuir-Blodgett (LB)method and investigated anisotropy electrical conduction characteristics by I-V measurement for horizontal direction and vertical direction. Also, we measured gad response between deposited LB films and organic gas for various temperature(0~8$0^{\circ}C$) by 9MHz At-cut quartz crystal microbalance. The LB films have electrical conduction characteristics such as semiconducting and insulating properties. The is, the conductivity of LB films for the horizontal and vertical direction is about 10\ulcornerS/cm and 10\ulcorners/cm, respectively. the frequency shift of stearic acid LB films for the organic gases depended on the mass change by the surface adsorption and the inner penetration to the sensing films. The resonant frequency shift of the quartz crystal microbalance for temperature properties of LB films is thought to the effect of the rearrangement or the damage pf LB films above the melting point and the mobility increasement of the organic gas by the temperature rising.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.263-264
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• 2006

본 연구에서는 Arachidic acid Langmuir-Blodgett (LB)막의 계면특성과 전기적 특성을 측정하였다. Arachidic aicd는 포화지방산으로 ($CH_3(CH_2)_{18}COOH$)의 구조를 가지며, 크기가 27.5[$\AA$]으로 $CH_3(CH_2)_{18}$의 소수기와 COOH의 친수기로 구성되어 있다. LB막은 박막제작시 배열과 배향의 제어가 용이하다. Chloroform을 용매로 하여 2[mmol/l]의 농도를 조성하여 ${\pi}-A$ 등온선을 통해 기체 상태, 액체 상태, 고체 상태를 관찰하였으며 편광각 현미경 (Brewster angle microscopy) 이미지를 통해 각 상태에서의 이미지를 관찰하였다. 또한 LB막의 제작시 사용되어진 ITO 기판은 친수처리 전 후의 접촉각의 측정을 통하여 막의 안정성을 확인하였다. 또한 LB막을 Metal/LB막/Metal 구조의 소자로 제작하여 전압-전류 특성을 측정하였다.

• 한국전기전자재료학회논문지
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• 제19권8호
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• pp.724-731
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• 2006

We investigated the electrochemical properties for Langmuir-Blodgett (LB) films mixed with 4-octyl-4'-(5-carboxylpentamethyleneoxy)azobenzene (denoted as 8A5H) and phospholipid(L-a-dimyristoylphosphatidylcholine, denoted as DMPC and L-a-dilauroylphosphayidylcholine, denoted as DLPC). The LB films of 8A5H, 8A5H-DMPC and 8A5H-DLPC mixture monolayers were deposited by using the LB method on the indium tin oxide(ITO) glass. The electrochemical properties measured by using cyclic voltammetry with a three-electrode system, an Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode at various concentrations(0.1, 0.5, and 1.0 mol/L) of $NaClO_4$ solution. A measuring range was reduced from initial potential to -1350 mV, continuously oxidized to 1650 mV and measured to the initial point. The scan rates were 50, 100, 150 and 200 mV/s, respectively. As a result, LB films of 8A5H and 8A5H-DLPC mixture monolayers appeared irreversible process caused by only the oxidation current from the cyclic voltammogram and LB films of 8A5H-DMPC monolayer mixture was found to be caused by a reversible oxidation-reduction process.

• 센서학회지
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• 제28권1호
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• pp.23-29
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• 2019

A copper tetracumylphenoxy phthalocyanine (CuPccp) thin film was formed on an organic insulator film by Langmuir-Blodgett (LB) deposition for gas sensor fabrication. To increase the reproducibility of film transfer, stearyl alcohol was used as a transfer promoter. The structural properties of the CuPccp layers were optically monitored through attenuated total reflection and polarization-modulated ellipsometry techniques. The average thickness of a single layer of the CuPccp LB film was measured to be 2.5 nm. Despite the role of the transfer promoter, the stability of the layer transfer was not sufficient to ensure homogeneity of the LB film. This was probably due to the presence of aggregates in the molecular structure of the CuPccp LB film. Nevertheless, copper phthalocyanine polymorphism can be greatly suppressed by the LB arrangement, which appears to contribute to the improvement of electrical conductivity. The p-type semiconductor characteristics were confirmed by Hall measurements from the CuPccp LB films.

• Bulletin of the Korean Chemical Society
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• 제26권12호
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• pp.2027-2032
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• 2005

This paper demonstrates details of thermal behavior of Langmuir-Blodgett (LB) film of poly(tert-butyl methacrylate) (PtBMA) by using the principal component analysis based two-dimensional correlation spectroscopy (PCA2D) through eigenvalue manipulating transformation (EMT). By uniformly lowering the power of a set of eigenvalues associated with the original data, the smaller eigenvalues becomes more prominent and the subtle contribution from minor components is now highlighted much more strongly than the original data. Thus, the subtle difference of thermal behavior of LB film of PtBMA from minor components, which is not readily detectable in the conventional 2D correlation analysis, is much more noticeable than the original data. PCA2D correlation spectra with EMT operation for the temperature-dependent IR spectra of LB film of PtBMA reveal the hidden property of phase transition processes during heating.