• 한국세라믹학회지
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• 제44권2호
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• pp.89-92
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• 2007

PbSe, with a band gap in the mid-infrared and a samll effective mass, is an interesting material for optical and electrical applications in infrared region. Various colloidal synthetic routes for synthesizing PbSe quantum dot nanoparticles have been developed in the last couple of years. In this work, stable colloidal solutions containing crystalline PbSe particles in the order of 5-15 nm were synthesized using different amount of acetic acid in high boiling coordinating solvents. The size and shape of PbSe nanoparticles was greatly influenced by coexistence of acetic acid in synthetic medium. It was observed by TEM that the shape of PbSe nanoparticles with different amount of acetic acid was changed from spherical to cube or star types.

• 공업화학전망
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• 제23권6호
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• pp.14-24
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• 2020

최근 우수한 발광 특성을 갖는 양자점을 고해상도 디스플레이의 발광 소재로 도입하고자 하는 노력이 활발하다. 양자점을 활용한 디스플레이의 실현을 위해서는 콜로이드 상태인 다색의 양자점을 고해상도로 패터닝하는 기술의 확립이 필요하다. 본 연구에서는 ethane-1,2-diyl bis(4-azido-2,3,5,6-tetrafluorobenzoate)를 양자점용 가교제로 활용하여 용액공정을 기반으로 형성된 양자점 박막을 고해상도로 패터닝한 기술을 소개하고자 한다. 위 양자점용 가교제의 양 말단에는 아지드 그룹을 포함한 작용기가 존재한다. 아지드 기는 자외선에 의해 광 활성화되어 양자점 표면의 알킬 리간드와 가교 결합을 형성함으로써, 양자점 박막에 화학적 내구성을 부여한다. 본 기술을 기반으로, 적색, 녹색, 청색의 카드뮴 기반 양자점을 고해상도로 패터닝하고 정밀하게 배열하여 인치 당 화소 수 1400 이상의 픽셀 형성에 성공하였다. 또한 가교 반응 후에도 성능 저하가 없는 양자점 박막 및 자발광 양자점 다이오드를 개발하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.420.1-420.1
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• 2016

Colloidal quantum dot (CQD) is emerging as a promising active material for next-generation solar cell applications because of its inexpensive and solution-processable characteristics as well as unique properties such as a tunable band-gap due to the quantum-size effect and multiple exciton generation. However, the most widely used spin-coating method for the formation of the quantum dot (QD) active layers is generally hard to be adopted for high productivity and large-area process. Instead, the spray-coating technique may potentially be utilized for high-throughput production of the CQD solar cells (CQDSCs) because it can be adapted to continuous process and large-area deposition on various substrates although the cell efficiency is still lower than that of the devices fabricated with spin-coating method. In this work, we observed that the subsequent treatment of two different ligands, halide ion and butanedithiol, on the lead sulfide (PbS) QD layer significantly enhanced the cell efficiency of the spray CQDSCs. The maximum power conversion efficiency was 5.3%, comparable to that of the spin-coating CQDSCs.

• 한국세라믹학회지
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• 제55권2호
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• pp.174-177
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• 2018

ZnO/Ag/ZnO multilayers were fabricated and their optical properties were investigated in terms of the micro-cavity effect in electroluminescent devices based on colloidal quantum dots. The top and bottom ZnO layers were formed by a sol-gel method while the middle Ag layer was deposited by thermal evaporation. After the fabrication of the ZnO/Ag/ZnO structure, the transmittance increased to 74%. When the oxide/metal/oxide multilayers were applied to quantum dot light-emitting diodes, the color purity was enhanced due to the narrower full width at half maximum.

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.953-958
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• 2007

Anchoring quantum dots (QDs) onto thermodynamically stable, large band gap oxide semiconductors is a very important strategy to enhance their quantum yields for solar energy conversion in both visible and near-IR regions. We describe a general procedure for anchoring a few chalcogenide QDs onto the titanium oxide layer. To anchor the colloidal QDs onto a mesoporous TiO2 layer, linker molecules containing both carboxylate and thiol functional groups were initially attached to TiO2 layers and subsequently used to capture dispersed QDs with the thiol group. Employing the procedure, we exploited cadmium selenide (CdSe) and cadmium telluride (CdTe) quantum dots (QDs) as inorganic sensitizers for a large band gap TiO2 layer of dye-sensitized solar cells (DSSCs). Their attachment was confirmed by naked eyes, absorption spectra, and photovoltaic effects. A few QD-TiO2 systems thus obtained have been characterized for photoelectrochemical solar energy conversion.

• 한국세라믹학회지
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• 제55권6호
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• pp.515-526
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• 2018

Cesium lead halide ($CsPbX_3$) nanocrystals have emerged as a new family of semiconductor nanomaterials that can outperform existing semiconductor nanocrystals owing to their superb optical and charge transport properties. Although these materials are expected to have many superior properties, control of the quantum confinement and isoelectronic magnetic doping, which can greatly enhance their optical, electronic, and magnetic properties, has faced significant challenges. These obstacles have hindered full utilization of the benefits that can be obtained by using $CsPbX_3$ nanocrystals exhibiting strong quantum confinement or coupling between exciton and magnetic dopants, which have been extensively explored in many other semiconductor quantum dots. Here, we review progress made during the past several years in tackling the issues of introducing controllable quantum confinement and doping of $Mn^{2+}$ ions as the prototypical magnetic dopant in colloidal $CsPbX_3$ nanocrystals.

• 전기전자학회논문지
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• 제27권1호
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• pp.30-37
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• 2023

양자점 발광 다이오드(QD-LED)의 효율과 안정성 향상을 위해서 QD 발광층에 주입되는 전하의 균형을 이루는 것은 필수이다. 산화 아연(ZnO)은 최신 QD-LED에서 전자수송층(electron transport layer, ETL)을 구성하기 위해 가장 많이 사용되고 있으나, ZnO의 자발적인 전자 주입은 QD-LED의 성능을 크게 열화시키는 과도한 전자 주입을 유발한다. 본 연구에서는 자기조립단분자막(self-assembled monolayer, SAM) 처리를 통해 ZnO의 전자 주입 특성을 조절하여 QD-LED의 성능을 향상시켰다. 전하 균형도를 향상시킨 결과, SAM을 처리한 QD-LED는 SAM을 처리 안한 소자와 비교하여 내부 양자 효율(external quantum efficiency, EQE)이 25%, 최대 휘도는 200% 향상되었다.

• Journal of Microbiology and Biotechnology
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• 제26권8호
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• pp.1457-1463
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• 2016

Vibrio anguillarum, a devastating pathogen causing vibriosis among marine fish, is prevailing in worldwide fishery industries and accounts for grievous economic losses. Therefore, a rapid on-site detection and diagnostic technique for this pathogen is in urgent need. In this study, two mouse monoclonal antibodies (MAbs) against V. anguillarum, 6B3-C5 and 8G3-B5, were generated by using hybridoma technology and their isotypes were characterized. MAb 6B3-C5 was chosen as the detector antibody and conjugated with quantum dots. Based on MAb 6B3-C5 labeled with quantum dots, a modified dot blot assay was developed for the on-site determination of V. anguillarum. It was found that the method had no cross-reactivity with other than V. anguillarum bacteria. The detection limit (LOD) for V. anguillarum was 1 × 10³ CFU/ml in cultured bacterial suspension samples, which was a 100-fold higher sensitivity than the reported colloidal gold immunochromatographic test strip. When V. anguillarum was mixed with turbot tissue homogenates, the LOD was 1 × 10³ CFU/ml, suggesting that tissue homogenates did not influence the detection capabilities. Preenrichment with the tissue homogenates for 12 h could raise the LOD up to 1 × 10² CFU/ml, confirming the reliability of the method.

• 한국분말재료학회지
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• 제31권2호
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• pp.169-179
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• 2024

양자점 패터닝 기술은 최근 QLED, 센서, laser, 태양전지, 양자컴퓨터 등을 포함한 광전자 응용분야에서 많은 수요가 예상되고 있다. 최근 양자점 패터닝을 위한 다양한 기술이 등장했지만 여전히 실제 산업에 적용에는 힘든 실정이다. 1~100 ㎛에 걸친 다양한 패턴 크기를 구현할 수 있는 전사프린팅은 대면적화가 어렵고 공정과정 중 발생할 수 있는 양자점 필름의 불완전한 박리 문제로 인한 패터닝 수율 문제가 보고 되고 있다. 기존 반도체 공정을 활용할 수 있는 포토리소그래피를 활용한 양자점 패터닝은 초고해상도로 픽셀을 패터닝 할 수 있다는 장점이 있지만, 포토레지스트를 제거하기 위해 쓰이는 용매에 의해 양자점 패턴 자체가 손상될 수도 있고 오염되어 광 효율이 낮아질 수 있다는 우려가 있다. 포토레지스트를 사용하지 않고 양자점의 용해도를 활용한 직접 광경화 공정이 주목받았지만, 패터닝 과정 중 생기는 결함과 비방사성 재결합으로 인해 양자점의 발광 효율이 떨어진다는 단점이 있어 표면 처리 등의 연구가 더욱 요구된다. 잉크젯 프린팅은 대면적화가 쉽고 상대적으로 경제적이라는 장점이 있으나 패턴의 불균일성과 낮은 해상도의 단점이 있다. 다양한 양자점 패터닝 방법 기술개발을 통해 QLED 소자에만 국한되는 것이 아니라 태양전지, 양자 통신, 양자 컴퓨터 등에도 적용이 기대된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.432.2-432.2
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• 2014

Recently, colloidal core/shell type quantum dots lighting-emitting diodes (QDLEDs) have been extensively studied and developed for the future of optoelectronic applications. In the work, we fabricate an inverted CdSe/ZnS quantum dot (QD) based light-emitting diodes (QDLED)[1]. In order to reduce work function of indium tin oxide (ITO) electrode for inverted structure, a very thin (<10 nm) polyethylenimine ethoxylated (PEIE) is used as surface modifier[2] instead of conventional metal oxide electron injection layer. The PEIE layer substantially reduces the work function of ITO electrodes which is estimated to be 3.08 eV by ultraviolet photoemission spectroscopy (UPS). From transmission electron microscopy (TEM) study, CdSe/ZnS QDs are uniformly distributed and formed by a monolayer on PEIE layer. In this inverted QD LED, two kinds of hybrid organic materials, [poly (9,9-di-n-octyl-fluorene-alt-benzothiadiazolo)(F8BT) + poly(N,N'-bis (4-butylphenyl)-N,N'-bis(phenyl)benzidine (poly-TPD)] and [4,4'-N,N'-dicarbazole-biphenyl (CBP) + poly-TPD], were adopted as hole transport layer having high highest occupied molecular orbital (HOMO) level for improving hole transport ability. At a low-operating voltage of 8 V, the device emits orange and red spectral radiation with high brightness up to 2450 and 1420 cd/m2, and luminance efficacy of 1.4 cd/A and 0.89 cd/A, respectively, at 7 V applied bias. Also, the carrier transport mechanisms for the QD LEDs are described by using several models to fit the experimental I-V data.