• Journal of the Semiconductor & Display Technology
• /
• v.21 no.3
• /
• pp.119-124
• /
• 2022

Top emission organic light-emitting diode (TEOLED) is commonly used because of high efficiency and good color purity than bottom - emission organic light-emitting device (BEOLED). Unlike BEOLED, TEOLED contain semitransparent metal cathode and capping layer. Because there are many characteristics to consider just simple thickness change, optimizing organic thickness of TEOLED for microcavity is difficult. So, in this study, we optimized Device capping layer at unoptimized micro-cavity structure TEOLED device. And we compare only capping layer with unoptimized microcavity structure can overcome optimized micro-cavity structure device. We used previous our optimized micro-cavity structure to compare each other. As a result, it has been found that the efficiency can be obtained almost the same or higher only capping layer, which is stacked on top of the device and controls only the thickness and refractive index, without complicated structural calculations. This means that higher efficiencies can be obtained more easily in laboratories with limited organic materials or when optimizing new structures etc.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.1
• /
• pp.87-96
• /
• 2019

Flexible organic light-emitting diode (OLED) displays with organic thin-film transistors (OTFTs) backplanes have been studied. A gate driver is required to drive the OLED display. The gate driver is integrated into the panel to reduce the manufacturing cost of the display panel and to simplify the module structure using fabrication methods based on low-temperature, low-cost, and large-area printing processes. In this paper, pseudo complementary metal oxide semiconductor (CMOS) logic gates are implemented using OTFTs for the gate driver integrated in the flexible OLED display. The pseudo CMOS inverter and NAND gates are designed and fabricated on a flexible plastic substrate using inkjet-printed OTFTs and the same process as the display. Moreover, the operation of the logic gates is confirmed by measurement. The measurement results show that the pseudo CMOS inverter can operate at input signal frequencies up to 1 kHz, indicating the possibility of the gate driver being integrated in the flexible OLED display.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.157-157
• /
• 2010

본 논문에서는 OLED (organic light-emitting device)의 광추출효율을 향상시키기 위한 마이크로 렌즈를 개발하였다. 차세대 평판디스플레이 및 차세대 면광원으로 주목받고 있는 OLED는 자발광소자이며, 빠른 응답속도와 넓은 시야각, 낮은 구동 전압등의 장점을 가지고 있다. 하지만 OLED는 아직까지 해결해야할 여러 가지 문제점들을 가지고 있다. 특히, 휘도와 수명 특성은 OLED의 운명을 좌우한다. OLED의 발광층에서 생성된 빛은 내부에서의 웨이브 가이드 효과 등으로 인하여 약 25%정도만이 외부로 방출되는 것으로 알려져 있다. 내부에서 반사되어 소멸되거나 측면으로 방출되는 빛을 OLED 전면으로 방출시키기 위한 마이크로 렌즈를 제작하였고 광추출향상율은 8%이었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.491-492
• /
• 2006

We report on the fabrication of organic-based flexible display using an amorphous IZO anode grown at room temperature. The IZO anode films were grown by a conventional DC reactive sputtering on polycarbonate (PC) substrate at room temperature using a synthesized IZO target in a Ar/$O_2$ ambient. X-ray diffraction examination results show that the IZO anode film grown at room temperature is complete amorphous structure due to low substrate temperature. It is shown that the $Ir(ppy)_3$ doped flexible organic light emitting diode (OLED) fabricated on the IZO anode exhibit comparable current-voltage-luminance characteristics to OLED fabricated on conventional ITO/glass substrate. These findings indicate that the IZO anode film grown on PC substrate is a promising anode materials for the fabrication of organic based flexible displays.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.6
• /
• pp.451-456
• /
• 2013

To study emission properties of white phosphorescent organic light emitting devices (PHOLEDs), we fabricated white PHOLEDs of ITO(150 nm) / NPB(30 nm) / TcTa(10 nm) / mCP(7.5 nm) / light-emitting layer(25 nm) / UGH3(5 nm) / Bphen(50 nm) / LiF(0.5 nm) / Al(200 nm) structure. The total thickness of light-emitting layer with co-doping and blue-doping/co-doping using a host-dopant system was 25 nm and the dopant of blue and red was FIrpic and $Bt_2Ir$(acac) in UGH3 as host, respectively. The OLED characteristics were changed with position and thickness of blue doping layer and co-doping layer as light-emitting layer and the best performance seemed in structure of blue-doping(5 nm)/co-doping(20 nm) layer. The white PHOLEDs showed the maximum current density of $34.5mA/cm^2$, maximum brightness of $5,731cd/m^2$, maximum current efficiency of 34.8 cd/A, maximum power efficiency of 21.6 lm/W, maximum quantum efficiency of 15.6%, and a Commission International de L'Eclairage (CIE) coordinate of (0.367, 0.436) at $1,000cd/m^2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.9
• /
• pp.581-586
• /
• 2015

We studied optical and electrical properties of two-wavelength white tandem organic light-emitting diodes using red and blue materials. White fluorescent OLEDs were fabricated using Alq3 : Rubrene (3 vol.% 5 nm) / SH-1 : BD-2 (3 vol.% 25 nm) as emitting layer (EML). White single fluorescent OLED showed maximum current efficiency of 9.7 cd/A, and tandem fluorescent OLED showed 18.2 cd/A. Commission Internationale de l'Eclairage (CIE) coordinates of single and tandem fluorescent OLEDs was (0.385, 0.435), (0.442, 0.473) at $1,000cd/m^2$, respectively. White hybrid OLEDs were fabricated using SH-1 : BD-2 (3 vol.% 10 nm) / CBP : $Ir(mphmq)_2(acac)$ (2 vol.% 20 nm) as EML. White single hybrid OLED showed maximum current efficiency of 7.8 cd/A, and tandem hybrid OLED showed 26.4 cd/A. Maximum current efficiency of tandem hybrid OLED was more twice as high as single OLED. CIE coordinates of single hybrid OLED was (0.315, 0.333), and tandem hybrid OLED was (0.448, 0.363) at $1,000cd/m^2$. CIE coordinates in white tandem OLEDs compared to those for single OLEDs observed red shift. This work reveals that stacked white OLED showed current efficiency improvement and red shifted emission than single OLED.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.66-69
• /
• 2007

We have investigated printing techniques for processing organic light-emitting diodes (OLEDs). We succeeded to gravure print uniform organic thin films as well as screen print low work function cathode for OLED structure. Furthermore, by using roll-to-roll manufacturing methods, we have been able to fabricate all-printed flexible OLED demonstrator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.377-377
• /
• 2007

A simplified integration process including packaging is presented, which enables the realization of the portable fluorescence detection system. A fluorescence detection microchip system consisting of an integrated PIN photodiode, an organic light emitting diode (OLED) as the light source, an interference filter, and a microchannel was developed. The on-chip fluorescence detector fabricated by poly(dimethylsiloxane) (PDMS)-based packaging had thin-film structure. A silicon-based integrated PIN photo diode combined with an optical filter removed the background noise, which was produced by an excitation source, on the same substrate. The active area of the finger-type PIN photo diode was extended to obtain a higher detection sensitivity of fluorescence. The sensitivity and the limit of detection (LOD S/N = 3) of the system were $0.198\;nA/{\mu}M$ and $10\;{\mu}M$, respectively.

• Journal of the Optical Society of Korea
• /
• v.15 no.4
• /
• pp.362-367
• /
• 2011

Organic ($Alq_3$) film, which was coated on a donor plate, was transferred to an organic light emitting diode (OLED) substrate with help of heat generated by a dithering laser beam. The laser beam was diffracted in an acousto-optic modulator (AOM), then focused on the laser-to-heat converting layer of the donor plate; the focused spot followed trajectories guided by rotation of a Galvano-mirror. Three different functional waveforms, sine wave, square wave, and saw tooth wave were applied to the AOM as modulation signal to generate the dithering beam. The fluorescence microscope images of the donor plate showed that the patterns of removed $Alq_3$ film were affected considerably by the modulation waveforms and the phase difference between adjacent dithering beams. Further, the printed images of Alq3 film on the OLED substrate were different from the patterns of removed Alq3 film. Atomic force microscope images indicated that not only direct transfer but also deposition by sublimated vapor of Alq3 contributed to the pattern formation. Printed patterns affected considerably the electricity-to-light conversion characteristics of OLEDs. For uniform transfer, not only the phase relation of dithering beam lines but also adequate waveform were important.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.6
• /
• pp.861-866
• /
• 2018

In OLED (Organic Light-Emitting Diode) manufacturing, the aging process increases the manufacturing efficiency and measures the correction value to correct the aging. The correction value for correcting the aging of the OLED can be applied to the driving signal. The OLED aging process measures the current after outputting the light for a predetermined time according to the preset driving signal and temperature. In the OLED manufacturing process, aging is applied for non-uniformity by deposition and temperature. This time has little effect on OLED efficiency reduction. Heating devices and signal generation systems are required to create the conditions necessary for aging. The results measured by the heating system and signal generation system can be used as a basis for evaluating power requirements, uniformity and efficiency in OLED manufacturing. In this paper, we propose and implement a configuration for interlocking the driving signal generation and heating system for practical OLED aging correction.