Polymeric micro-capsules for a stable storage of quantum dot (QD) : QD-microcapsules

서영수 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

QD has been known as a promising material for the next generation display and illumination technology due to its excellent luminescent properties such as narrow emission band and high efficiency comparable to OLED. Until now, however, its application as industrial products is still limited because it is easily degraded under oxidative environments such as atmospheric oxygen, heat, and moisture. Here we developed a polymeric microcapsule where QD is well-dispersed in between self-assembled, 2-dimensionally stacked (multi-larmellar), micron-sized polymeric crystals, which is referred as a QD-microcapsule. it has been applied to QD-film and QD-LED and we found long-term stability of QD has been improved tested at high temperature, high humidity, and under the blue light. Its morphology was studied by SEM, TEM, WASX, and SAXS. Stability of QD was checked in terms of photoluminescence (PL) intensity, emission wavelength, and FWHM in the PL spectrum.

The photo-characteristics of (Bi_1−<i>x</i>Zn_<i>x</i>)S quantum dot complex and multilayer structure for the application to the dye-sensitized solar cell

Son, Min-Kyu,Seo, Hyunwoong,Shin, Inyoung,Kim, Jin-Kyoung,Choi, Jinho,Prabakar, K.,Kim, Hee-Je Elsevier 2011 Current Applied Physics Vol.11 No.1

<P><B>Abstract</B></P><P>In recent years, many quantum dot (QD) materials were investigated and applied as the sensitizer replacing organic dyes in the dye-sensitized solar cell (DSC). QD materials can tune their band gap energy level and this characteristic offers new opportunity to improve the light harvest ability. Generally, there is an inverse relationship between the band gap energy and the light absorbance. Therefore, the light absorbance of QD material can expand to the long wavelength region as the band gap energy is decreased. In this study, the light harvest ability is improved as (Bi<SUB>1 − <I>x</I></SUB>Zn<SUB><I>x</I></SUB>)S QD complex and multilayer structure are fabricated by using two QD materials (Bi<SUB>2</SUB>S<SUB>3,</SUB> ZnS). The band gap energy is controlled by the amount of the bismuth(Bi) and the zinc(Zn). And then, the light absorbance becomes wide as the amount of Bi is more than that of Zn. In addition, (Bi<SUB>1 − <I>x</I></SUB>Zn<SUB><I>x</I></SUB>)S QD multilayer structure is fabricated by using these (Bi<SUB>1 − <I>x</I></SUB>Zn<SUB><I>x</I></SUB>)S QD complexes having different amounts of the Bi and Zn. Finally, it is demonstrated that (Bi<SUB>1 − <I>x</I></SUB>Zn<SUB><I>x</I></SUB>)S QD multilayer is the appropriate structure to strengthen the light harvest ability and this QD complex is possible to apply to the DSC as sensitizer for the high efficiency.</P> <P><B>Highlights</B></P><P>► (Bi<SUB>1−<I>x</I></SUB>Zn<SUB><I>x</I></SUB>)S quantum dot complex as the sensitizer of the dye sensitized solar cell. ► The photo-characteristics of (Bi<SUB>1−<I>x</I></SUB>Zn<SUB><I>x</I></SUB>)S are changed by controlling the amount of the bismuth and zinc. ► Multilayer is introduced for improving the light absorbance. ► This quantum dot complex and multilayer structure can be applied to the dye sensitized solar cell.</P>

InP/ZnSe/ZnS 양자점을 이용한 QD-LED의 전기 및 광학적 특성

최재건,문대규,Choi, Jae-Geon,Moon, Dae-Gyu 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.3

We have developed quantum dot light emitting diodes (QD-LEDs) using a InP/ZnSe/ZnS multi-shell QD emission layer. The hybrid structure of organic hole transport layer/QD/organic electron transport layer was used for fabricating QD-LEDs. Poly(4-butylphenyl-diphenyl-amine) (poly-TPD) and tris[2,4,6-trimethyl-3-(pyridin-3-yl)phenyl]borane (3TPYMB) molecules were used as hole-transporting and electron-transporting layers, respectively. The emission, current efficiency, and driving characteristics of QD-LEDs with 50, 65 nm thick 3TPYMB layers were investigated. The QD-LED with a 50 nm thick 3TPYMB layer exhibited a maximum current efficiency of 1.3 cd/A.

Highly stable QD-LED by organic and inorganic dual-encapsulation

박상율,서영수 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1

The unique optical properties of quantum dot (QD) have stimulated active researches for the next generation display and illumination. Especially, it attracts great attention in high definition display because it has narrow emission band and high efficiency for replacing OLED. Even so, it is very hard to apply it for industrial products because the optical properties of QD were degraded by oxygen, heat, and moisture. Moreover, photo-stability should be guaranteed too. To enhance QD stability, previously we developed a polymeric microcapsule. Here we present a novel method for strengthening barrier and thermal properties of the microcapsule using inorganic materials. Morphology was studied by SEM and TEM. Stability of QD was checked by life test of QD-LED in terms of applying voltages.

Sensitive detection of virus with broad dynamic range based on highly bright quantum dot-embedded nanoprobe and magnetic beads

Ahla Jo,Tae-Han Kim,Dong-Min Kim,김형모,Bomi Seong,Jaehi Kim,Xuan-Hung Pham,정흥수,Sang Hun Lee,Do Won Hwang,Dae Hong Jeong,Yoon-Sik Lee,Dong-Eun Kim,Bong-Hyun Jun 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.90 No.-

As virus spread can lead to severe epidemics and pandemics associated with high mortality, it is necessary to have a highly sensitive detection method for viruses. Although various detection methods have been developed so far, current methods in detecting a virus require preprocessing and involve quite intricate processes of low sensitivity. Here, we have developed a virus detection method with a broad dynamic range and high sensitivity, based on immuno-complex formation between quantum dot (QD)- embedded silica nanoparticles (QD2 ) and magnetic beads. The multiple QD- containing QD2 s showed 500 times stronger photoluminescence than individual QDs. When biotin was immobilized as a ligand, streptavidin was detected in a range of 10 zM to 10 nM. The clinical applicability of the QD2 -based system was examined using the avian virus (i.e., H1N1 influenza virus), and it showed a detection range of 4.76 × 10-4 < span class="xps_thinspace"> ~ 3.2 hemagglutination unit/mL. This result is comparable to the polymerase chain reaction method, and is approximately 2100 times more sensitive than the conventional hemagglutination method. Since the QD2 -based system could detect target molecules with high sensitivity without requiring an amplification step, it can be applied in various biomedical and clinical fields.

정공수송층의 재료에 대한 QD-LEDs의 전기 및 광학적 특성 연구

하미영,김강희,문대규 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

나노결정 양자점 및 이를 활용한 디스플레이는 높은 발광효율, 우수한 색재현성 및 색순도, 소자의 안정성 및 용액공정에 대한 용이성 등을 강점으로 가진다. 본 연구에서는 이와 같이 우수한 특성의 QD(Quantum-Dot)를 발광층으로 사용하고, 용액공정 및 열증착 공정을 이용하여 하이브리드 형태의 고효율 양자점 발광 소자(QD-LEDs)를 제작하였다. 특히, 최적의 QD-LEDs의 소자 제작을 위하여 정공수송층의 재료로 정공 이동도가 우수하고, 용액 공정 시, 적층에 용이한 재료인 Poly-TPD [Poly(N,N’-bis(4- butylphenyl)-N,N’-bis(phenyl)-benzidine] 및 PVK (Poly(N-vinyl carbazole)를 이용하였으며, 각 재료별 두께의 변화에 따라서 QD-LEDs의 전기적, 광학적 특성을 분석하였다. 우리는 Poly-TPD를 정공수송층으로 활용한 녹색 QD-LEDs에서 두께가 250 nm일 때, 14.8cd/A (@ 0.102 mA/cm²)의 최대 전류효율을 얻었다. 또한, PVK의 경우는 두께가 100 nm일 때, 11.8cd/A (@ 0.001 mA/cm²)의 전류효율을 가졌다. 이와 같은 결과로 두 재료의 전자 및 정공의 밸런스가 서로 다른 특징을 가지는 것을 알 수 있고, 이것은 두 물질의 정공이동도에 기인한 것으로 사료된다.

Development of microbiochip for detection of metalloproteinase 7 using fluorescence resonance energy transfer

이승용,한병욱,박찬수,정제식,안정진,하승모,황승용,안유민 한국바이오칩학회 2013 BioChip Journal Vol.7 No.2

A protease is any enzyme that catalyzes the hydrolysis of proteins into smaller peptide fragments and amino acids, a process known as proteolysis. They are involved in a multitude of normal biological processes as well as in diseases, including cancer,stroke and infections. Here we present a microfluidicbased assay system to detect proteolytic activity using fluorescence resonance energy transfer (FRET) by quantum dot (QD)-peptide conjugates immobilized on microbeads. As an energy donor, QD was immobilized on the microbead surface by the avidin-biotin interaction. As an energy acceptor, the fluorophorelabeled peptide was then associated with QD, thus quenching the photoluminescence (PL) of the QD. The functionalized microbeads were introduced into the microbiochip and captured by a micropillar in the reaction chamber. In the presence of matrix metalloprotease-7 (MMP-7) as a model protease, the PL of QD quenched by fluorophore was recovered due to the proteolytic activity of MMP-7 in the fabricated microbiochip. Moreover, the FRET efficiency induced by MMP-7 was linearly dependent on the logarithmic concentration of MMP-7. This technology is not limited to sensing MMP-7, but could be used to monitor other protease activities (Schematic diagram).

저분자 화합물을 이용한 유기 전계발광소자의 제작과 특성 연구

노준서,조중연,유정희,장영철,장호정 한국마이크로전자및패키징학회 2003 마이크로전자 및 패키징학회지 Vol.10 No.1

본 연구에서는 ITO (indium tin oxide)/glass 투명기판 위에 다층구조의 OELD (organic electroluminescent devices) 소자를 진공 열증착법으로 제작하였다. 발광층 재료로서 Alq$_3$(tris-(8-hydroxyquinoline)aluminum)물질을 사용하였고, 정공수송층으로는 TPD (triphenyl-diamine) 및 $\alpha-NPD$를 사용하였다. 정공주입층 재료로서 CuPc (Copper phthalocyanine)를 사용하였다. 또한 QD2(quinacridone2) 물질을 $Alq_3$ 발광층내에 약 $10\AA$ 두께로 증착하여 발광효율 향상을 시도하였다. 제작된 모든 소자의 발광개시전압은 약 7 V 이었으며, 정공수송층으로 TPD 물질대신에 열적안정성이 우수한 $\alpha-NPD$를 사용한 경우 휘도값과 발광효율이 개선되었다. $Alq_3$ 발광층 사이에 QD2 물질을 적층한 소자에서 발광효율은 1.55 lm/W 값을 나타내어 $Alq_3$ 발광층만을 사용한 경우에 비해 약 8배 발광효율이 향상되었다. The multi-layered OELDs(organic electroluminescent devices) were prepared on the patterened ITO (indium tin oxide)/glass substrates by the vacuum thermal evaporation method. The $Alq_3$ (tris-(8-hydroxyquinoline)aluminum) low molecule compound was used as the light emission layer. TPD(triphenyl-diamine) and $\alpha-NPD$ were used as the hole transport layer. CuPc (Copper phthalocyanine) was also used as the hole injection layers. In addition, QD2 (quinacridone2) organic material with $10\AA$ thickness was deposited in the $Alq_3$ emission layer to improve the luminance efficiency. The threshold voltage was about 7V for all devices. The luminance and efficiency of devices was improved by substitution the $\alpha-NPD$ for TPD as the hole as the hole transport layer. The luminance efficiency of the OELD sample with QD2 thin film in the $Alq_3$ emission layer was found to be 1.55 lm/W, which is about 8 times larger value compared to the sample without QD2 thin layer.

Higher-Order Masking Scheme against DPA Attack in Practice: McEliece Cryptosystem Based on QD-MDPC Code

( Mu Han ),( Yunwen Wang ),( Shidian Ma ),( Ailan Wan ),( Shuai Liu ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.2

A code-based cryptosystem can resist quantum-computing attacks. However, an original system based on the Goppa code has a large key size, which makes it unpractical in embedded devices with limited sources. Many special error-correcting codes have recently been developed to reduce the key size, and yet these systems are easily broken through side channel attacks, particularly differential power analysis (DPA) attacks, when they are applied to hardware devices. To address this problem, a higher-order masking scheme for a McEliece cryptosystem based on the quasi-dyadic moderate density parity check (QD-MDPC) code has been proposed. The proposed scheme has a small key size and is able to resist DPA attacks. In this paper, a novel McEliece cryptosystem based on the QD-MDPC code is demonstrated. The key size of this novel cryptosystem is reduced by 78 times, which meets the requirements of embedded devices. Further, based on the novel cryptosystem, a higher-order masking scheme was developed by constructing an extension Ishai-Sahai-Wagne (ISW) masking scheme. The authenticity and integrity analysis verify that the proposed scheme has higher security than conventional approaches. Finally, a side channel attack experiment was also conducted to verify that the novel masking system is able to defend against high-order DPA attacks on hardware devices. Based on the experimental validation, it can be concluded that the proposed higher-order masking scheme can be applied as an advanced protection solution for devices with limited resources.

Improvement of Quantum Dot Light-Emitting Device Efficiency by Using Multi-functional Bipyridine Ligands

Choi Yoon-Jeong,Lee Chil Won,Kim Jang Sub 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.12

This paper report on the significantly improved performance of InP/ZnSeS/ZnS quantum dot (QD) devices with multi-functional ligands. These quantum dots in which the monodentate ligand oleylamine is coordinated to the shell surface are reacted with the delocalized bipyridine bidentate ligand, where some oleylamine is replaced by bipyridine. The coordination of the delocalized bidentate bipyridine ligand results in many electronic property changes in the QD-LED (light emitting diode) device. 1H-NMR (nuclear magnetic resonance) and TGA (thermogravimetric analysis) data indicated that up to 60.6% of the native ligands were partially exchanged with the bipyridine ligands. Photoluminescence (PL) spectra before and after ligand substitution show a bathochromic shift of about 2.6 nm due to the electrical resonant properties of the bipyridine ligands. QD-LED devices were fabricated using QDs with substituted bipyridine ligand, and significant improvements in the device properties were observed. Here, we first report the ligand dependence of the photo- and the electroluminescence of green InP/ZnSeS/ZnS quantum dots in QD-LED devices.