• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.145.1-145.1
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• 2008

• Current Photovoltaic Research
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• 제2권4호
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• pp.152-156
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• 2014

We report hybrid solar cells fabricated with polymer/fullerene bulk heterojunction layers that contain inorganic nanocrystals synthesized by in-situ reaction in the presence of polymer chains. The inorganic (cadmium sulfide) nanocrystal ($CdS_{NC}$) was generated by the reaction of cadmium acetate and sulfur by varying the reaction time up to 30 min. The synthesized $CdS_{NC}$ showed a rectangular flake shape, while the size of $CdS_{NC}$ reached ca. 150 nm when the reaction time was 10 min. The performance of hybrid solar cells with $CdS_{NC}$ synthesized for 10 min was better than that of a control device, whereas poor performances were measured for other hybrid solar cells with $CdS_{NC}$ synthesized for more than 10 min.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.28-28
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• 2008

We have demonstrated the combinatorial synthesis of a variety of transparent conducting oxides using a combinatorial sputter system. The effects of a wide range of Nb or Zn doping rate on the optical and electrical properties of Indium-tin oxides (ITO) films were investigated. The Nb or Zn doped ITO films were fabricated on glass substrates, using combinatorial sputtering system which yields a linear composition spread of Nb or Zn concentration in ITO films in a controlled manner by co-sputtering two targets of ITO and $Nb_2O_5$ or ITO and ZnO. We have examined the work-function, resistivity, and optical properties of the Nb or Zn-doped ITO films. Furthermore, the effects of Hz plasma treatment on the physical properties of Ga or Zn doped ITO films synthesized by combinatorial sputter system were investigated.

• Current Photovoltaic Research
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• 제4권2호
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• pp.48-53
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• 2016

We report the effect of physical load on the stability of organic solar cells under physical loads. The active layers in organic solar cells were fabricated with bulk heterojunction films (BHJ) films of poly (3-hexylthiophene) and phenyl-$C_{61}$-butyric methyl ester. The loading time was varied up to 60 s by keeping the physical load constant. Results showed that the open circuit voltage was not influenced by the physical load but other solar cell parameters were sensitive to the loading time. The fill factor was very slightly increased at 15 s, while short circuit current density was well kept for 30 s. The power conversion efficiency was reasonably maintained for 45 s but became significantly decreased by the continuous loading for 60 s.

• Current Optics and Photonics
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• 제7권5호
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• pp.496-503
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• 2023

We present a detailed analysis of the light extraction efficiency (LEE) of a core-shell nanorod light emitting diode (LED) using finite-difference time-domain (FDTD) simulations. We found that the LEE has a deep dependence on source positions and polarization directions based on the calculated LEE results for every x and z position inside the core-shell nanorod structure. The LEEs are different for the upper part (pyramid) and the lower part (sidewall) of the core-shell nanorod owing to total internal reflection (TIR) and the generated optical modes in the structure. As a result, the LEE of sidewall is much larger than that of pyramid. The averaged LEE of the core-shell nanorod LED is also investigated with variable p-GaN thickness, n-GaN thickness, and height for the design guidelines for the optimized LEE of core-shell nanorod LEDs.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.5.2-5.2
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• 2009

Carbon based nanoelctronic materials such as buckyball, CNT, and graphene have been active field of research because of their superior electronic prperties and potential application to flexible electronics. Still the difficulty of fabrication and spatial control prevent them from practical applications. Here I introduce a novel growth method of CNTs, known as surface assisted growth, that can answer the challenge. Various device examples from as-grown CNTs will prove the importance of this method for future nanoelectronics.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2496-2503
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• 2018

The short-term stability of high efficiency polymer : nonfullerene solar cells was investigated by employing a quick (ten cycles) current density-voltage (J-V) cycling method. Polymer : nonfullerene solar cells with initial power conversion efficiency (PCE) of >10% were fabricated using bulk heterojunction (BHJ) films of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5,7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6/7-methyl)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (IT-M). One set of the BHJ (PBDB-T : IT-M) films was thermally annealed at $160^{\circ}C$ for 30min, while another set was used without any thermal treatment after spin-coating. The quick J-V scan (cycling) measurement disclosed that the PCE decay was relatively slower for the annealed BHJ layers than the unannealed (as-cast) BHJ layers. As a result, after ten cycles, the annealed BHJ layers delivered higher PCE than the unannealed BHJ layers due to higher and more stable trend in fill factor. The present quick J-V cycling method is simple but expected to be useful for the prediction of short-term stability in organic solar cells.

• Current Photovoltaic Research
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• 제7권3호
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• pp.55-60
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• 2019

Polymer:nonfullerene solar cells with an inverted-type device structure were fabricated by employing the bulk heterojunction (BHJ) active layers, which are composed of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophene-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(6-methyl-2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3-d']-s-indaceno[1,2-b:5,6-b']dithiophene (IT-M). The BHJ layers were formed on a pre-patterned indium-tin oxide (ITO)-coated glass substrate by spin-coating using the blend solutions of PBDB-T and IT-M. The solar cell performances were investigated with respect to the cell position on the ITO-glass substrates. In addition, the short-term shelf lifetime of solar cells was tested by storing the PBDB-T:IT-M solar cells in a glovebox filled with inert gas. The results showed that the performance of solar cells was relatively higher for the cells close to the center of substrates, which was maintained even after storage for 24 h. In particular, the PCE of PBDB-T:IT-M solar cells was marginally decreased after storage for 24 h owing to the slightly reduced fill factor, even though the open circuit voltage was unchanged after 24 h.

• 대한전자공학회논문지SD
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• 제44권11호
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• pp.56-64
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• 2007

본 논문은 CMOS-나노 혼성 소자들 중 실현 가능성이 높은 CMOL 회로 설계 자동화 전용 시스템을 최초로 제안한다. CMOL 아키텍처는 NOR 게이트를 이용하여 조합회로의 구현한다. 이 CMOS-나노 혼성 구조는 논리 함수 및 연결 구조가 동일 나노 소자 하드웨어 자원을 공유하는 특징을 가진 새로운 설계 자동화 문제를 제기한다. CMOL의 물리 설계 자동화를 위해 먼저 CMOL 하드웨어 아키텍처 모델을 개발하고 이 CMOL 구조를 위한 배치 배선 문제에서 CMOL만의 특수한 제약조건을 도출하였으며 배치 알고리즘과 게이트 지정 알고리즘을 루프 형태로 조합하여 해를 구하는 접근 방법을 제안하였다. 제안된 접근 방법을 사용하여 CMOL 나노 전자 아키텍처를 위한 전용 설계 자동화 시스템을 개발하였으며 이 시스템을 이용하여 마이크로프로세서 설계에 실제 사용되는 모듈들을 구현함으로써 그 효용성을 증명하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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• pp.41-41
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• 2008

Al-doped ZnO (AZO) thin films have been fabricated by vertical in-line dc magnetron sputtering for transparent conducting oxides (TCOs) applications. The effects of substrate temperature and dc power on the characteristics of AZO thin films are investigated and also optimized the process conditions to get the best electrical and optical properties. The fabricated thin films show a good electrical and optical uniformity within ${\pm}5%$ over the whole area of substrate ($200mm\;{\times}\;200mm$) ; the minimum resistivity of $8\;{\times}\;10^{-4}\;{\Omega}cm$ and the average transmittance of 90% within the visible wavelength range. We have found that the band gap ($E_g$) increases with increasing substrate temperature and dc power, whereas the crystallinity is getting improved with increasing substrate temperature. The binding energy of Zn $2p_{3/2}$ and O 1s is observed to decrease as the substrate temperature increases.