• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
• /
• pp.784-787
• /
• 2002

Oganic light emitting diodes (OLEDs) using PBD(2-(4-biphenylyl)-5-(4-tert-butylpheny)-1,3,4oxadiazole) as a hole blocking layer were fabricated and their device performances were investigated. The devices have a structure of glass substrate ${\setminus}$ indium tin oxide (ITO) ${\setminus}$ TPD(HTL)${\setminus}$PBD,BCP(HBL)${\setminus}$Alq3(EIL)${\setminus}$Mg:Ag(cathode). In this work Bathocuproine(BCP:2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline) and PBD which were previously known as a good ETL material were used as a HBL. By employing HBL, the luminance and quantum efficiency of OLEDs could be improved due to the increase of recombination probability of electrons and holes.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
• /
• pp.316-318
• /
• 2004

In this study, the influence of electromagnetic wave effected on human body of light sensing was classified. Subjects of the eye was stimulated by the rays of LED and the measured electrical signals(EEG, EOG and ERG) in human body were compared and analyzed in the case of exposed at electromagnetic wave or not. The result show that when the subjects were not exposed at electromagnetic wave, the ratio of a wave has a large percentage in the EEG signal and the ratio of $\beta$ wave has come to good.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
• /
• pp.741-744
• /
• 2007

The research applied the processes of spin-coating and thermal-evaporating in proper order to deposit the hole transport material N,N'-Bis(naphthalen-1-yl)- N,N'-bis(phenyl)-benzidine (NPB) on the ITO substrate to make flexible organic light emitting diodes (FOLED) with double hole transport layer.

• Bulletin of the Korean Chemical Society
• /
• 제33권5호
• /
• pp.1627-1637
• /
• 2012

The coupling reaction between 5-bromo-3-phenylbenzo[c]isoxazole and diphenylamine followed by further condensation with a mono-, di- or ter-acetyl aromatic compound in the presence of diphenyl phosphate at $145^{\circ}C$ gave a novel asymmetric diarylquinolines, oligoquinolines with diphenylamine endgroups, and a first generation quinoline dendrimer in 41-82% isolated yield. The electrochemical and photophysical properties of the oligoquinolines were characterized by cyclic voltammograms (CVs) and spectroscopy. All the quinolines emit bright sky blue light due to charge transfer from quinoline group to diphenly amine with very high quantum efficiency (> 90%). Organic light-emitting diodes (OLEDs) were fabricated using these quinolines as emitting materials. Among different device architectures explored, OLEDs with a structure of ITO/PEDOT (40 nm)/TAPC (15 nm)/D-A quinoline (40 nm)/TPBI (30 nm)/LiF (1 nm)/Al using TAPC as an electron blocking layer and TPBI as a hole blocking layer gave the best performance. A high external quantum efficiency in the range of 1.2-2.3% were achieved in all the quinolines with the best performance in BBQA(5). Our results indicate diarylamino-substituted oligoquinoline and dendrimer are promising materials for OLEDs applications.

• 한국표면공학회지
• /
• 제56권4호
• /
• pp.233-242
• /
• 2023

In recent years, energy-management studies in buildings have proven useful for energy savings. Typically, during heating and cooling, the energy from a given building is lost through its windows. Generally, to block the entry of ultraviolet (UV) and infrared (IR) rays, thin films of deposited metals or metal oxides are used, and the blocking of UV and IR rays by these thin films depends on the materials deposited on them. Therefore, by controlling the thicknesses and densities of the thin films, improving the transmittance of visible light and the blocking of heat rays such as UV and IR may be possible. Such improvements can be realized not only by changing the two-dimensional thin films but also by altering the zero-dimensional (0-D) nanostructures deposited on the films. In this study, 0-D nanoparticles were synthesized using a sol -gel procedure. The synthesized nanoparticles were deposited as deep coatings on polymer and glass substrates. Through spectral analysis in the UV-visible (vis) region, thin-film layers of deposited zinc oxide nanoparticles blocked >95 % of UV rays. For high transmittance in the visible-light region and low transmittance in the IR and UV regions, hybrid multiple layers of silica nanoparticles, zinc oxide particles, and fluorine-doped tin oxide nanoparticles were formed on glass and polymer substrates. Spectrophotometry in the UV-vis-near-IR regions revealed that the substrates prevented heat loss well. The glass and polymer substrates achieved transmittance values of 80 % in the visible-light region, 50 % to 60 % in the IR region, and 90 % in the UV region.

• 마이크로전자및패키징학회지
• /
• 제29권4호
• /
• pp.29-34
• /
• 2022

위상지연 필름을 이용하여 가시광선 투과도 제어가 가능한 스마트윈도우 제작 기술을 제안한다. 위상지연 필름의 phase retardation(𝚪)이 𝛑/2(𝚫n·d = 𝛌/4)인 경우 선편광을 원편광으로 변환시켜줄 수 있으며, 서로 다른 배향각도를 갖는 두 장의 𝛌/4 위상지연 필름을 이용하여 광투과 모드(45°/-45°)와 광차단 모드(45°/45°) 제어가 가능한 스마트윈도우를 제작할 수 있다. 본 연구에서는 복굴절 물질인 reactive mesogen (RM)의 두께에 따른 retardation 특성(𝚫n·d)을 평가함으로써 𝚫n·d가 𝛌/4인 위상지연 필름을 제작하였다. 서로 다른 𝚫n·d 값을 갖는 위상지연 필름이 적용된 스마트윈도우의 광차단 특성을 평가한 결과, 𝛌/4 위상지연 필름 기반의 스마트윈도우에서 가장 높은 광차단율(≥20%)을 보였다. 이를 통해 𝚫n·d의 값이 𝛌/4 일 때 위상지연 효과가 가장 높다는 것을 확인하였으며, 𝛌/4 위상지연 필름을 적용하여 150×150 mm² 크기의 스마트윈도우를 구현하였다.

• Transactions on Electrical and Electronic Materials
• /
• 제12권6호
• /
• pp.241-244
• /
• 2011

An isolator transmits light in the forward direction and blocks light from passing in the reverse direction. It is regarded an essential optical component in medical, industrial, and research lasers for blocking reflection beams that cause optical damage and noise. It is also used as a communicative light intensifier to expand the lifespan of devices and enhance transmission quality. This study analyzed the characteristics of the core components in the construction of a polarization-independent isolator, namely, the walk-off polarizer and the Faraday rotator. Measurement of the extinction ratio of the resultant walk-off polarizer revealed that the ratio between the vertical and horizontal rays was 1,050:1 with a laser output of 0.032 W and 1,010:1 with a laser output of 2.68 W, thus presenting ratios similar to 1,000:1. In addition, the walk-off polarizer and Faraday rotator constructed in this study were used to compare output changes according to changes in power of input light and to check the penetration ratio. Results from the study presented variations in output value according to changes in power of input light. However, the average penetration ratio remained relatively consistent (~81.4%).

• Journal of Multimedia Information System
• /
• 제7권4호
• /
• pp.239-248
• /
• 2020

The performance of the facial recognition system is determined by many technical factors. Further, most of the technical factors have been realized or are still in continued research. The recognition rate has a great influence on performance not only by technical factors but also by other factors. However, researchers are trying to improve the recognition rate by focusing only on technical factors. The mechanism of recognizing is to compare a face image obtained by photography to an already stored face image and determine the score of the similarity. However, if the photographed image is damaged by external light, even a system with a good algorithm will fail to recognize it. Therefore, it is important to prevent the disturbance of light entering from the outside, so it should be blocked, but the camera will not work without light. Thus, it is proposed that a method to secure the external light but block the disturbance of light that affects photography. A method of blocking disturbance light is to use a polarization filter. There are three polarization methods: circular polarization, linear polarization, and elliptical polarization. In this paper, an experiment was performed to overcome disturbance of light using only a circularly polarized filter. In addition, a lighting system that reproduces disturbance light was provided for the experiment, and light of varying intensities and angles was installed to affect the face recognition camera. As a result of actual application, it was determined that a very improved recognition performance in various disturbance light environments.

• Korean Chemical Engineering Research
• /
• 제54권2호
• /
• pp.274-277
• /
• 2016

녹색 발광다이오드의 다양자우물층과 전자막이층 사이에 p형 중간층 삽입이 소자의 특성에 미치는 영향이 소자 시뮬레이션을 통하여 연구되었다. 중간층의 Mg 도핑 깊이에 따른 발광다이오드의 전류-전압, 발광파장, 누설전류, 광효율 특성이 분석되었으며 최적의 발광 특성을 나타내는 소자 구조가 제시되었다. 중간층 전 영역이 p형으로 도핑된 구조와 30 nm까지 도핑된 구조는 누설전류 억제를 통하여 녹색 발광다이오드의 가장 큰 문제점 중에 하나인 효율 드룹 현상을 효과적으로 완화하였다. 특히, 30 nm까지 도핑된 구조는 전류-전압 및 발광 특성에 있어서 가장 향상된 결과를 보였다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
• /
• pp.937-939
• /
• 2003

We synthesized and characterized new fluorene-based polyquinoxalines with ether-linkage in the main chain, which have luminescent properties. Cyclic voltammetry reveals that these polymers have a low-lying LUMO and HOMO energy levels. Therefore, the polymers would be attractive candidates for electron-tansporting or hole-blocking materials in LEDs.