• Proceedings of the KSME Conference
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• 2007.05a
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• pp.441-445
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• 2007

In this paper we demonstrated the applications of OTFTs (organic thin film transistors) to flexible displays such as AM-EPD (active matrix electrophoretic display) and AM-OLED (active matrix organic light emitting diode), and also to integrated circuits. The OTFTs using pentacene semiconductor layer and PVP gate dielectric and Au S/D electrodes exhibited good performance for AM-EPD with the mobility of $0.59\;cm^{2}/V.sec,$ and with also good uniformity over 2.5" diagonal area. However, it is nor enough for AM-OLED requiring the mobility larger than $1\;cm^{2}/V.sec$ for large area displays. The integrated circuits also worked, producing the operating frequency of 1MHz. We need to develop a fabrication process to reduce parasitic capacitance for high frequency operation.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.7-10
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• 2016

The post cleaning method for clean the shadow mask using in OLED (organic light emitting diode) emitter layer is always reforming. The cleaning solution and analysis method of shadow mask is still lack and not optimized. We use the simple and useful analytical method to determine the quantity and quality of organic and inorganic residue on surface of shadow mask. Finally analyze the cleaning solution using Raman spectroscopy efficiently.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.126-129
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• 2020

We introduce a lifetime assessment technique using deep learning algorithm with complex electrical parameters such as resistivity, permittivity, impedance parameters as integrated indicators for predicting the degradation of the organic molecules. The evaluation system consists of fully automated in-situ measurement system and multiple layer perceptron learning system with five hidden layers and 1011 perceptra in each layer. Prediction accuracies are calculated and compared depending on the physical feature, learning hyperparameters. 62.5% of full time-series data are used for training and its prediction accuracy is estimated as r-square value of 0.99. Remaining 37.5% of the data are used for testing with prediction accuracy of 0.95. With k-fold cross-validation, the stability to the instantaneous changes in the measured data is also improved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.25-26
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• 2008

In this paper, the white organic light-emitting diode(OLED)was fabricated using the DPVBi of blue emitting material and a rubrene of orange color of fluorescent dye by vacuum evaporation processes. The device structure of OLED was Glass/ITO/2T-NATA(15nm)/NPB(3nm)/DPVBi(3nm)/DPVBi rubrene[2%](10nm)/DPVBi(25nm)/$Alq_3$ or New-ETL(60nm) /LiF(0.5nm)/ Al(100nm). The device with the $Alq_3$, layer shows orange color, and the luminance of 1000cd/$m^2$ at an applied voltage of 10.4V. On the other hand, the New-En layer results in white color, CIE coordinates of (0.327, 0.323), and the lowered driving voltage of 5V for achieving the same luminance value.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.2
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• pp.113-119
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• 2003

We report the electrical properties of copper(II)-phthalocyanine(Cu-Pc) as a hole injaction layer in organic light-emitting diode (OLED). OLEDs were constructed by the following material structure : indium tin oxaide (ITO)/ CuPc/ triphenyl-diamine (TPD)/ tris-(8-hydroxyquinoline)aluminum (Alq3)/4-(Dicyanomethlene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)/ Al. we observed that the change of recombination zone by using a DCM detection thin layer (6 ${\AA}$) in a Alq$_3$ emitting layer. layer. Recombination zone was moved toward the cathode as the hole mobility increased due to the heat-treatment temperature of cupc layer increased.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.69-74
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• 2019

The aim of this work is to investigate the effect of the microtip length in a slot-die head on coating of a fine poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) stripe. To this end, we have employed a meniscus guide with a 150-㎛-wide microtip and performed roll-to-roll slot-die coatings by varying its length between 500 ㎛ and 50 ㎛. When the microtip length is 150 ㎛ or shorter, we have observed three unexpected phenomena; 1) though the solution spreads much wider than the microtip width, yet the coated stripe width is almost the same as the microtip width, 2) the stripe width decreases, but the stripe thickness is rather increased with increasing coating speed at a fixed flow rate, 3) we obtain stripes much narrower than the microtip width at high coating speeds. It is due to the fact that 1) the meniscus is not well controlled by a short microtip, 2) the main stream of solution from the outlet is very close to the substrate and thus the distributed solution along the head lip merges with the main stream, and 3) the solution is not spread over the entire microtip end at high coating speeds, causing a tiny wobble in the meniscus. Using the 150-㎛-wide and 250-㎛-long microtip, we have fabricated 153-㎛-wide and 94-nm-thick PEDOT:PSS stripe at the maximum coating speed of 13 mm/s. To demonstrate its applicability in solution-processable organic light-emitting diodes (OLEDs), we have also fabricated an OLED device with the fine PEDOT:PSS stripe and obtained strong light emission from it.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1267-1270
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• 2006

Organic light-emitting diode (OLED) display panel with $64\;{\times}\;64$ pixels utilizing the charge-pump (CP) pixel addressing method was fabricated using conventional thin-film processes. Each pixel consists of a-Si:H Schottky diode and $ITO/SiO_2/ITO$ capacitor. It is shown that CP-OLED is technically feasible for information display and a driving voltage below $4V_{pp}$ is enough for nominal operation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.6
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• pp.510-514
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• 2005

We have investigated the excitation-light source dependence of photo-catalytic efficiency for the benzene removal. The photo-catalytic module for the benzene removal is fabricated by a combination of GaN-based ultraviolet light-emitting diode (UV GaN-LED) and $TiO_2$ thin film coated on an aluminum plate. The benzene reduction rates of 365 nm and 375 nm modules at 60 mA junction current are approximately $8.95\;\%/Hr$ and $9.2\;\%/Hr$, respectively, which indicates that 365 nm GaN-LED is more effective than 375 nm GaN-LED. The benzene reduction efficiency is also noticeably dependent on the excitation wavelength and excitation-light power, as well as it is increased with the shorter wavelength and higher excitation power. This result exhibits that UV GaN-LED is useful to remove the volatile organic compounds (VOCs) existing in the environment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.193-197
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• 2004

The organic light emitting diode (OLED) is proposed as the novel source in the microchip because it has ideal merits (various wavelengths, thin-film structure and overall emitting) for the integration. In this paper, we fabricated the finger-type pin photodiodes for fluorescence detection and the advanced microchip with OLED integrated pn the microchannel. The finger-type in the diode design extended the depletion region and reduced the internal resistance about 31.2% than rectangular-type. The photodiodes had a 100pA leakage current and a 8720 sensitivity $(I_{Light}/I_{Dark})$ at -1 V bias. The interference filter with 32 layers ($SiO_2$, $TiO_2$) was directly deposited on the photodiode. The OLED was fabricated on the ITO coated glass and was bonded with LOC. The application of thin-film OLED increased the excitation efficiency and simplified the integration process extremely. The prototype device of this application had a superior sensitivity of 100nM-LOD in the fluorescence detection.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.146-146
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• 2011

The blue light emitting diode (LED) structure based on non-polar a-plane (11-20) GaN which was coated TiO2 nanoparticles using spin coating method was grown on r-plane (1-102) sapphire substrates to improve light extraction efficiency. We report on the emission and structural properties with temperature dependence of photoluminescence (PL) and x-ray rocking curves (XRC). From PL results at 13 K of undoped GaN samples, basal plane stacking fault (BSF) and near band edge (NBE) emission peak were observed at 3.434 eV and 3.484 eV, respectively. We also found the temperature-induced band-gap shrinkage, which was fitted well with empirical Varshini's equation. The PL intensity of TiO2 nanoparticles ?coated multiple quantum well (MQW) sample is decayed slower than that of no coating sample with increasing temperature. The anisotrophic strain and azimuth angle dependence in the films were shown from XRC results. The full width at half maximum (FWHM) along the GaN [11-20] and [1-100] directions were 564.9 arcsec and 490.8 arcsec, respectively. A small deviation of FWHM values at in-plane direction is attributed to uniform in-plane strain.