• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.137-140
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• 2005

Organic light emitting transistors (OLET) which are vertically combined with the organic static induction transistor (OSIT) and organic light emitting diode (OLED) are fabricated and the device characteristics are investigated. High luminance modulations by relatively low gate voltages are obtained. In order to realize the flexible electronic circuits and displays, we have fabricated OSIT on plastic substrates. The OSIT fabricated on plastic substrate show almost same characteristics comparing with those of nonflexible OSIT on glass substrate. The OLET described here is a suitable element for flexible sheet displays.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.7-10
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• 2022

A functional polyethylene terephthalate substrate to increase light extraction efficiency of organic light-emitting diodes is studied. We formed nano-structured PET surfaces by controlling the power, gas, and exposure time of the linear ion-beam. The haze of the polyethylene terephthalate can be controlled from 0.2% to 76.0% by changing the peak-to-valley roughness of nano structure by adjusting the exposure cycle. The treated polyethylene terephthalate shows average haze of 76.0%, average total transmittance of 86.6%. The functional PET increases the current efficiency of organic light-emitting diodes by 47% compared to that of organic light-emitting diode on bare polyethylene terephthalate. In addition to polyethylene terephthalate with light extraction performance, by conducting additional research on the development of functional PET with anti-reflection and barrier performance, it will be possible to develop flexible substrates suitable for organic light-emitting diodes lighting and transparent flexible displays.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1374-1377
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• 2005

Top-emitting organic light-emitting diode (TEOLED) was fabricated on flexible substrate of PES film. Aluminum and Chromium multilayer was used as an anode of TEOLED and the TEOLEDs of Cr(20nm)/Al(100nm)/Cr(20nm)/NPB(60nm)/Alq(60nm)/LiF(1nm)/Al(2nm)/Ag(20nm)/NPB(200nm) has been fabricated on PES film and Si wafer for control device. The TEOLED on PES film which had good anode surface morphology, showed very similar device characteristics to that on Si wafer.

• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.124-129
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• 2015

Organic electronics are the domain in which the components and circuits are made of organic materials. This new electronics help to realize electronic and optoelectronic devices on flexible substrates. In recent years, organic materials have replaced conventional semiconductors in many electronic components such as, organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic (OPVs). It is well known that organic light emitting diodes (OLEDs) have many advantages in comparison with inorganic light-emitting diodes LEDs. These advantages include the low price of manufacturing, large area of electroluminescent display, uniform emission and lower the requirement for power. The aim of this paper is to model polymer LEDs and OLEDs made with small molecules for studying the electrical and optical characteristics. The purpose of this modeling process is, to obtain information about the running of OLEDs, as well as, the injection and charge transport mechanisms. The first simulation structure used in this paper is a mono layer device; typically consisting of the poly (2-methoxy-5(2'-ethyl) hexoxy-phenylenevinylene) (MEH-PPV) polymer sandwiched between an anode with a high work function, usually an indium tin oxide (ITO) substrate, and a cathode with a relatively low work function, such as Al. Electrons will then be injected from the cathode and recombine with electron holes injected from the anode, emitting light. In the second structure, we replaced MEH-PPV by tris (8-hydroxyquinolinato) aluminum (Alq₃). This simulation uses, the Poole-Frenkel -like mobility model and the Langevin bimolecular recombination model as the transport and recombination mechanism. These models are enabled in ATLAS- SILVACO. To optimize OLED performance, we propose to change some parameters in this device, such as doping concentration, thickness and electrode materials.

• Advanced Industrial SCIence
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• v.1 no.1
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• pp.16-22
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• 2022

Starting with cathode ray tubes, displays are forming markets in the order of active marix organic light emitting diode (AMOLED) after PDP (Plasma Display Panel) and LCD (Liquid Crystal Display). OLED is recognized as a key field for the development of each country preparing for the fourth industrial revolution, and especially Samsung Display and LG Display, which are the top industries in Korea, are leading the market with more than 90% of OLED shares. Currently, AMOLED has moved to the area that can be folded or bent. This technology is possible because TFT (Thin Film Transistor) and OLED may be formed on a flexible substrate. In the future, the technology will move to stretchable displays, and for this, the development of substrate materials is first, and then TFT and OLED devices should also be implemented with stretchable materials.

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

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.1
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• pp.87-96
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• 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
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• 2005.11a
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• pp.269-270
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• 2005

A hybrid passivation method using parylene and silicon dioxide combination layer for a flexible organic light emitting diode (FOLED) was applied on a polycarbonate substrate. A parylene coating by vapor polymerization method is a highly effective passivation process for the FOLED, and it applies all top surface and the edges of the FOLED device. In order to minimize the permeation of moisture and oxygen from the top surface of the device, an additional layer of silicon dioxide was deposited over the parylene coated layer. It was found that the water vapor transmittance rate (WVTR) of parylene (15 m-in-thickness) / SiO2 (0.3$\mu$m-in-thickness) combination layers deposited on polycarbonate film was decreased under the value of 10-3 g/m2day. The FOLED with the hybrid passivation showed remarkably longer lifetime characteristics in the ambient conditions than the non-passivated FOLED. The lifetime of the passivated FOLED was 400 hours and it was more than ten times over the lifetime of the convectional non-passivated FOLED.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1390-1393
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• 2005

We fabricated an efficient top emission organic light emitting diode (FTEOLED) on paper substrates. For water proof and surface planarization, parylene of 5mm thick has been coated on copy paper substrate by vapor polymerization. As use this coating layer, fabrication of device was possible by photolithography and wet etching. Because paper is not transparent, we adapted top emission structure with transparent cathode and reflective anode. The FTOLED on paper showed the excellent electrical characteristic, $109cd/m^2$, 2.3cd/A at 10V.

• Journal of the Semiconductor & Display Technology
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• v.22 no.1
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• pp.23-27
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• 2023

Organic light-emitting diode(OLED) is very thin organic films which are hundreds of nanometers. Unlike bottom-emission OLED(BEOLED), top-emission OLED(TEOLED) emits light out the front, opaque moisture absorbents or metal foils can't be used to prevent moisture and oxygen. And it is difficult to have flexible characteristics with glass encapsulation, so thin film encapsulation which can compensate for those two disadvantages is mainly used. In this study, Al₂O₃ thin films by atomic layer deposition(ALD) were examined by changing the argon gas purge flow rate and we applied this Al₂O₃ thin films to the encapsulation of TEOLED. Ag / ITO / N,N'-Di-[(1-naphthyl)-N,N'-diphenyl]-1,1'-biphenyl-4,4'-diamine / tris-(8-hydroxyquinoline) aluminum/ LiF / Mg:Ag (1:9) were used to fabricate OLED device. The characteristics such as brightness, current density, and power efficiency are compared. And it was confirmed that with a thickness of 40 nm Al₂O₃ thin film encapsulation process did not affect OLED properties. And it was enough to maintain a proper OLED operation for about 9 hours.