• Macromolecular Research
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• v.10 no.2
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• pp.75-79
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• 2002

Organic materials have considerable attention as active semiconductors for device applications such as thin-film transistors (TFTs) and diodes. Pentacene is a p-type organic semiconducting material investigated for TFTs. In this paper, we reported the morphological and electrical characteristics of pentacene TFT films. The pentacene transistors showed the mobility of 0.8 $\textrm{cm}^2$/Vs and the grains larger than 1 ${\mu}{\textrm}{m}$. Deep-level transient spectroscopy (DLTS) measurements were carried out on metal/insulator/organic semiconductor structure devices that had a depletion region at the insulator/organic-semiconductor interface. The duration of the capacitance transient in DLTS signals was several ten of seconds in the pentacene, which was longer than that of inorganic semiconductors such as Si. Based on the DLTS characteristics, the energy levels of hole and electron traps for the pentacene films were approximately 0.24, 1.08, and 0.31 eV above Ev, and 0.69 eV below Ec.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.114-114
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• 2011

We report a high-performance and air-stable flexible and invisible semiconductor which can be substitute for the n-type organic semiconductors. N-type organic-inorganic nanohybrid superlattices were developed for active semiconducting channel layers of thin film transistors at low temperature of $150^{\circ}C$ by using molecular layer deposition with atomic layer deposition. In these nanohybrid superlattices, self-assembled organic layers (SAOLs) offer structural flexibility, whereas ZnO inorganic layers provide the potential for semiconducting properties, and thermal and mechanical stability. The prepared SAOLs-ZnO nanohybrid thin films exhibited good flexibility, transparent in the visible range, and excellent field effect mobility (> 7cm2/$V{\cdot}s$) under low voltage operation (from -1 to 3V). The nanohybrid semiconductor is also compatible with pentacene in p-n junction diodes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.497-499
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• 2005

A portable terminal assistant market grows rapidly every year and it requires many change in research on display devices. Among many newly developing methods, OLED(Organic Light Emitting Diode) is considered an advanced flat display device because its excellent characteristics, including high speed response, full color performance, low power consumption and flux of panel. However changes in the market of display shows that the market will require 3-dimensional images, but it is hard for existing 2-dimensional displays to make 3-dimensional images. Therefore we will try to find various methods such as holograms. In this paper, we will show existing flat displays can make 3-dimensional images by applying Lenticular Screen printing techniques on the organic semiconductor display device.

• Current Optics and Photonics
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• v.3 no.4
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• pp.336-341
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• 2019

This paper proposes an optical system where the organic compound content in water is determined by using an ultraviolet (UV) LED (280 nm) and photodetector. The results obtained by the proposed prototype LED spectroscopy system, which includes a single photodetector and two parallel sample holders, are calculated by applying partial least square regression; the values are highly correlated with the actual concentrations of potassium hydrogen phthalate solutions, with an adjusted coefficient of determination about 0.996. Moreover, the total organic carbon values derived from the UV-Vis spectrometer of real samples (lake, river and sea water) differed little from those obtained by the LED spectroscopy. We confirm that the fast, sensitive, and compact LED sensor system can be readily configured for real-time monitoring of organic compounds in water.

• Journal of Information Display
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• v.10 no.3
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• pp.111-116
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• 2009

In this paper, a plasma-assisted patterning method for the organic layers of organic light-emitting diodes (OLEDs) and its effect on the OLED performances are reported. Oxygen plasma was used to etch the organic layers, using the top electrode consisting of lithium fluoride and aluminum as an etching mask. Although the current flow at low voltages increased for the etched OLEDs, there was no significant degradation of the OLED efficiency and lifetime in comparison with the conventional OLEDs. Therefore, this method can be used to reduce the ohmic voltage drop along the common top electrodes by connecting the top electrode with highly conductive bus lines after the common organic layers on the bus lines are etched by plasma. To further analyze the current increase at low voltages, the plasma patterning effect on the OLED performance was investigated by changing the device sizes, especially in one direction, and by changing the etching depth in the vertical direction of the device. It was found that the current flow increase at low voltages was not proportional to the device sizes, indicating that the current flow increase does not come from the leakage current along the etched sides. In the etching depth experiment, the current flow at low voltages did not increase when the etching process was stopped in the middle of the hole transport layer. This means that the current flow increase at low voltages is closely related to the modification of the hole injection layer, and thus, to the modification of the interface between the hole injection layer and the bottom electrode.

• Journal of Adhesion and Interface
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• v.22 no.4
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• pp.144-152
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• 2021

Understanding charge transfer across the interface between organic semiconductor and gate insulator gives insight into the development of high-performance organic memory as well as highly stable organic field-effect transistors (OFETs). In this work, we firstly unveil a novel interfacial charge transfer mechanism, in which hole transfer from organic semiconductor to polymer insulator was nonlinearly boosted by localized states coupling. For this, OFETs based on rubrene single crystal semiconductor and Mylar gate insulator were fabricated via vacuum lamination, which allows stable repetition of lamination and delamination between semiconductor and gate insulator. The surfaces of rubrene single crystal and Mylar film were selectively degraded by photo-induced oxygen diffusion and UV-ozone treatment, respectively. Consequently, we found that the interfacial charge transfer and resultant bias-stress effect were nonlinearly boosted by coupling between localized states in rubrene and Mylar. In particular, the small number of localized states in rubrene single crystal provided fluent pathway for interfacial charge transport.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.563-565
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• 2009

We introduce the new modification approaches of photocrosslinkable poly (4-vinylphenol) (PVP) for low hysteresis organic thin film transistors (OTFTs). The dielectric layers were composed of different PVP resin, low molecular melamine, and halogen free photo-initiator. The low hysteresis OTFT from one of the organic gate dielectrics has been realized. The electrical performance of low hysteresis OTFT with photocrosslinkable PVP exhibited a field-effect mobility of 0.2 cm2/Vs, a threshold voltage of - 0.04V, hysteresis of 0.4V.

• Journal of the Semiconductor & Display Technology
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• v.19 no.2
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• pp.72-76
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• 2020

The author demonstrated organic ferroelectric thin-film transistors with ferroelectric materials of P(VDF-TrFE) and an amorphous oxide semiconducting In-Ga-Zn-O channel on the silicon substrates. The organic ferroelectric layers were deposited on an oxide semiconductor layer by Langmuir-Blodgett method and then annealed at 128℃ for 30min. The carrier mobility and current on/off ratio of the memory transistors showed 9 ㎠V^-1s^-1 and 6 orders of magnitude, respectively. We can conclude from the obtained results that proposed memory transistors were quite suitable to realize flexible and werable electronic applications.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1139-1141
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• 2006

For the bottom-contact pentacene organic thin-film transistors (OTFTs), the insertion of a thin PMMA layer $(20{\AA})$ between the pentacene and the electrode improves the electrical performances, such as carrier mobility and on-current magnitude, about 4 times larger than those of the devices without the PMMA. The performance enhancement is presumably due to the decreased contact resistance between metal and pentacene by inserting the thin PMMA layer.

• 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.