• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.477-478
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• 2005

The devices with a structure of ITO/$Alq_3$/Al were fabricated and their impedance properties were analyzed. It is obtained that an effect of resistance $R_p$ of the device was dominant at the low frequency and the high voltage region, emitting region, and it is ignored at the high frequency region. Capacitance $C_p$ appears intensely in a range of all frequencies of non-emitting region, below turn on voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.537-538
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• 2005

A way of measuring an efficiency of organic light-emitting diodes are studied. The efficiency is obtained from the current-voltage-luminance characteristics of the devices. Basically, number of charge carriers are obtained from the current-voltage characteristics, and the number of photons are obtained from the current of Si-photodetector. The organic light-emitting diodes are assumed as a lambertian light source and a program is made for calculating the efficiency. A device structure of ITO/TPD/$Alq_3$/Al is manufactured using thermal-vapor evaporation. This device is set into a measuring system and measured the efficiency. The efficiencies are measured using the lab-made program and commercially available equipments. The obtained values are similar to each other within 10% uncertainty.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.533-534
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• 2005

Temperature-dependent current-voltage characteristics of organic light-emitting diodes(OLEDs) were studied in a device structure of ITO/TPD/$Alq_3$/Al. The OLEDs were based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-l,1'-diphenyl-4,4'-diamine(TPD) as a hole transport and tris(8-hydroxyquinoline) aluminum($Alq_3$) as an electron transport and emissive material. The current-voltage characteristics were measured in the temperature range of 10K and 300K. We analyzed an electrical conduction mechanism of the OLEDs using space-charge-limited current(SCLC) and Fowler-Nordheim tunneling.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.67-68
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• 2006

Organic light-emitting devices (OLEDs) with the high efficiency and long lifetime are of growing interest in next-generation displays. Among the factors influencing OLEDs properties, one of unstable factor is $Alq_3$ cationic species caused by the excess holes resided in $Alq_3$ layer. Therefore, we suppressed the accumulation of excess holes by using the mixed-hole transporting layer (MHTL) of NPB and CBP in multilayer green OLEDs. The devices with MHTL showed improved characteristics in the luminance efficiency and lifetime. More characteristics and the carrier transport mechanism will be discussed.

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.6-10
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• 2018

Organic light emitting devices have attracted the attention of many people because of their high potential for self-emission and flexible display devices. However, due to limitations in device efficiency and lifetime, partial commercialization is underway. In this paper, we have investigated the electrical conduction mechanism of the organic light emitting device by the temperature and the thickness of the light emitting layer through the current - voltage characteristics with respect to the conduction mechanism directly affecting the efficiency and lifetime of the organic light emitting device. Through the study, it was found that the conduction in the low electric field region is caused by the movement of the heat excited charge in the ohmic region and the tunneling of the electric charge due to the high electric field in the high electric field region.

• Journal of the Semiconductor & Display Technology
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• v.17 no.1
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• pp.50-53
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• 2018

Cyclic measurement system using relay circuit for organic light emitting diode (OLED) was demonstrated. The OLED characterization such as current-voltage, impedance, and capacitance-voltage is performed in sequence, repetitively and automatically under full control of the personnel computer (PC) without changing the connection of cables. Owing to in situ degradation by cyclic measurement, the time dependence of the data can give good information on the reliability factor of the OLED devices. Therefore, both performance and reliability of the OLEDs can be evaluated, with no manual operation during the entire process.

• Journal of the Semiconductor & Display Technology
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• v.20 no.3
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• pp.131-135
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• 2021

Numbers of studies related to optimization of design of organic light emitting diodes(OLED) through machine learning are increasing. We propose the generative method of the image to assess the performance of the device combining with machine learning technique. Principle parameter regarding dark spot growth mechanism of the OLED can be the key factor to determine the long-time performance. Captured images from actual device and randomly generated images at specific time and initial pinhole state are fed into the deep neural network system. The simulation reinforced by the machine learning technique can predict the device parameters accurately and faster. Similarly, the inverse design using multiple layer perceptron(MLP) system can infer the initial degradation factors at manufacturing with given device parameter to feedback the design of manufacturing process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.4
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• pp.362-366
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• 2006

OLEDs(Organic Light Emitting Diodes) are attractive as alternative display components because of their relative merits of being self-emitting, having large intrinsic viewing angle and fast switching speed. But because of their relatively short history of development, much remains to be studied in terms of their basic device physics and design, manufacturing techniques, stability and so on. We investigated electrical properties of N, N-diphenyl-N, N bis (3-methyphenyl-l,1'-biphenyl-4,4'-diamine (TPD) and tris-8-hydroxyquinoline aluminum$(Alq_3)$ when their thicknesses were changed variedly from 3:7 to 5:5 of their thickness ratios. And we also studied properties of OLED depend on their deposition rate between $0.05{\sim}0.2$ nm/s.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.98-98
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• 1994

최근 청색반도체레이저의 실현을 위하여 ZnSe가 대표하는 II-Ⅵ족 화합물반도체와 Gan가 대표하는 III족 질화물반도체분야에서 집중적인 연구가 이루어지고 있으며, 아직까지 실용화 되지 않고 있는 청색반도체레이저의 출현에 대하여 많은관심이 모아지고 있다. III족 질화물반도체는 InM(Eg:1.9eV)부터 AIN(Eg: 6.2eV)에 이르기까지 전 조성영역에서 완전한 고용체를 이루며, 실온에서 직접천이형 에너지 대구조를 가지므로 청색 혹은 자외영역에서 동작하는 발광소자를 제작하는데 있어 유망시 되고 있는 소재이다. 특히 GaN와 InN의 3원흔정인 GaInN를 활성층으로 이용하면 그 발전파장을 370nm부터 650nm까지 즉 가시 전 영역으로부터 근 자외영역을 포함할 수 있게 된다. 이 연구에서는 AIGaN/GaInN 이중이종접합(DH) 구조의 고아여기에 의한 유도방출고아의 편광 특성을 조사하였다. 유기금속기상에피텍셜(MOVPE)법으로 성장한 AIGaN/GaInN DH 구조의 표면에 수직으로 펄스 발진 질소레이저(파장: 337.1cm, 주기 10Hz, 폭: 8nsec) 빔을 조사하고 DH구조의 단면으로부터의 유도방출광을 편광기를 통과 시킨 후 스펙트럼을 측정하였다. 입사고아 밀도가 증가함에 따라 약 402nm의 파장에서 유도발출에 의한 가도가 큰 피크가 나타났고, 그 반치폭은 약 18meV이었다. 실온에서 AIGaN/GaInN DH 구조로 부터의 유도방출에 필요한 입사광밀도의 임계치는 약 130㎾/$\textrm{cm}^2$이었다. 한편 편광각이 90$^{\circ}$일때는 발광스펙트럼의 강도가 매우 낮고 단지 자연방출에 의한 스펙트럼만이 나타났다. 편광각이 0$^{\circ}$일 때 최대의 방출광 강도를 나타내었으며, 편광각이 -90$^{\circ}$로 회전함에 따라 발고아강도의 강도가 감소하였다. 이와 같은 결과는 광여기에 의하여 AIGaN/GaInN DH 로 부터의 유도방출광이 GaInN활성층의 단면에 평행한 전기장의방향으로, 즉 TE모드로 선형적으로 편광됨을 의미한다. AIGaN/GanN DH 로 부터의 유도방출이 선형적으로 TE모드로 편광되는 것은 이 구조를 이용한 청색 및 자외선 반도체 레이저다이오드의 실현에 매우 유익한 것이다.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.61-65
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• 2024

The effectiveness of CuSCN as a hole injection layer in large-area organic light-emitting diodes, organic solar cells, and thin-film transistors has been well demonstrated. Therefore, in this study, the surface, optical, and electrical analyses of CuSCN were carried out according to the solution process conditions in order to propose optimized film conditions. Various CuSCN solution concentrations were prepared to determine the film surface characteristics and to determine whether the film surface affects the electrical performance of the device. When the CuSCN solution concentration was low, the CuSCN film was not formed and coated in the form of islands, and when the solution concentration was increased, the CuSCN film was formed uniformly, which contributed to improving the conductivity of the device. In addition, a hole-only device was fabricated to demonstrate the role of CuSCN as a hole transport layer.