• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.368-368
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• 2012

We report solution-processed, high-performance single-crystal organic nanowire transistors fabricated from a novel indolocarbazole (IC) derivative. The direct printing process was utilized to generate single-crystal organic nanowire arrays enabling the simultaneous synthesis, alignment and patterning of nanowires using molecular ink solutions. Using this method, single-crystal organic nanowires can easily be synthesized by self-assembly and crystallization of organic molecules within the nanoscale channels of molds, and these nanowires can then be directly transferred to specific positions on substrates to generate nanowire arrays by a direct printing process. These new molecules are particularly suitable for p-channel organic field-effect transistors (OFETs) because of the high level of crystallinity usually found in IC derivatives. Selected area diffraction (SAED) and X-ray diffraction (XRD) experiments on these solution-processed nanowires showed high crystallinity. Transistors fabricated with these nanowires gave a hole mobility as high as 1.0 cm2V-1s-1 with nanowire arrays with the direct printing process.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.266.1-266.1
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• 2013

Large-scale single-crystal organic nanowire arrays were generated using a direct printing method (liquidbridge- mediated nanotransfer molding) that enables the simultaneous synthesis, alignment and patterning of nanowires from molecular ink solutions. Using this method, single-crystal organic nanowires can easily be synthesized by self-assembly and crystallization of organic molecules within the nanoscale channels of molds, and these nanowires can then be directly transferred to specific positions on substrates to generate nanowire arrays by a direct printing process. Repeated application of the direct printing process can be used to produce organic nanowire-integrated electronics with two- or three-dimensional complex structures on large-area flexible substrates. This efficient manufacturing method is used to fabricate all-organic nanowire field-effect transistors that are integrated into device arrays and inverters on flexible plastic substrates.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.473-473
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• 2011

In recent years, organic thin film transistors OTFTs based on conductive-conjugated molecules have received significant attention. We report a fabrication of organic single crystal nanowires that made on Si substrates by liquid bridge-mediated nanotransfer molding (LB-nTM) with polyurethane acrylate (PUA) mold. LB-nTM is based on the direct transfer of various materials from a stamp to a substrate via a liquid bridge between them. In liquid bridge-transfer process, the liquid layer serves as an adhesion layer to provide good conformal contact and form covalent bonding between the organic single crystal nanowire and the Si substrate. Pentacene is the most promising organic semiconductors. However pentacene has insolubility in organic solvents so pentacene OTFTs can be achieved with vacuum evaporation system. However 6, 13-bis (triisopropylsilylethynyl) (TIPS) pentacene has high solubility in organic solvent that reported by Anthony et al. Furthermore, the substituted rings in TIPS-pentacene interrupt the herringbone packing, which leads to cofacial ${\pi}-{\pi}$ stacking. The patterned TIPS-Pentacene single crystal nanowires have been investigated by Atomic force microscopy (AFM), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and electrical properties.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.7
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• pp.508-513
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• 1999

The response properties of quartz crystal coated with stearic acid LB films to organic gases were investigated by measuring the shift of resonant frequency. Stearic acid was used as a sensing material and deposited on the surface of quartz crystal using the Langmuir-Blodgett(LB) method. The effect of temperature on the quartz crystal coated with stearic acid LB films was also investigated by Scanning Maxwell-stress Microscopy(SMM). As a result, the sensitivity of the quartz crystal coated with LB films to organic gases is dependent on temperature, thickness of LB film and molecular weight of organic gas.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.261.1-261.1
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• 2013

Well-aligned nanowire arrays can be used as building blocks for nanoscale device. Recently, we reported that well-aligned single-crystal organic nanowires has been created by using a direct printing method which is named liquid-bridge mediated nanotransfer molding (LB-nTM). Moreover, multi-layering nanostructures can be fabricated by repeating this printing process. As a result, it is possible to make simple and basic concept of heterojunction devices such as crossed nanowire devices. We fabricated crossed single-crystal organic nanowires nanojunction devices from 6,13-bis (triisopropylsilylethynyl) pentacene (TIPS-PEN) and fullerene (C60) single-crystal nanowires using by direct printing method in solution process. Crossed TIPSPEN/ C60 single-crystal nanowires diode has rectifying behavior with on/off ratios of ~13. In addition, the device shows photodiode characteristics as well as rectification. Our study represent methodology of heterojunction devices using single-crystal nanowires, thereby provide a new direction of future nanoelectronics.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.33-38
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• 1997

Fundamentals and industrial applications of crystallization of organic compounds are reviewed. The methods to upgrade organic products in terms of its purity and its morphology are introduced. How crystallization of organics can be useful in producing ultra-pure materials are also described.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.134.2-134.2
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• 2014

Photonic crystal solar cells have the potential for addressing the disparate length scales in polymer photovoltaic materials, thereby confronting the major challenge in solar cell technology: efficiency. One must achieve simultaneously an efficient absorption of photons with effective carrier extraction. Unfortunately the two processes have opposing requirements. Efficient absorption of light calls for thicker PV active layers whereas carrier transport always benefits from thinner ones, and this dichotomy is at the heart of an efficiency/cost conundrum that has kept solar energy expensive relative to fossil fuels. This dichotomy persists over the entire solar spectrum but increasingly so near a semiconductor's band edge where absorption is weak. We report a 2-D, photonic crystal morphology that enhances the efficiency of organic photovoltaic cells relative to conventional planar cells. The morphology is developed by patterning an organic photoactive bulk heterojunction blend of Poly(3-(2-methyl-2-hexylcarboxylate) thiophene-co-thiophene) and PCBM via PRINT, a nano-embossing method that lends itself to large area fabrication of nanostructures. The photonic crystal cell morphology increases photocurrents generally, and particularly through the excitation of resonant modes near the band edge of the organic PV material. The device performance of the photonic crystal cell showed a nearly doubled increase in efficiency relative to conventional planar cell designs. Photonic crystals can also enhance performance of other optoelectronic devices including organic laser.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.563-563
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• 2012

We report a one-step fabrication of single-crystal organic nanowire arrays on substrates using a new direct printing method (liquid-bridge-mediated nanotransfer moulding, LB-nTM), which can simultaneously enable the synthesis, alignment and patterning of the nanowires using molecular ink solutions. Two- or three-dimensional complex structures of various single-crystal organic nanowires were directly fabricated over a large area with a successive process. The position of the nanowires can be aligned easily on complex structures because the mold is movable on substrates before drying the polar liquid layer, which acts as an adhesive lubricant. This efficient manufacturing method can produce a wide range of optoelectronic devices and integrated circuits with single-crystal organic nanowires.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.261-263
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• 1996

The study on the development of one-channel gas sensor using the quartz crystal analyzer were attempted. The adsorption and desorption behavior of organic gases were investigated using the resonant frequency and resistance method of quartz crystal. The sensitive materials were deposited on the quartz crystal analyzer(QCA) by using Langmuir-Blodgett method. To investigate the response characteristics of organic vapours and response mechanism, resonant frequency-resonant resistance (F-R) diagram was used. In our experimental results, the response mechanism between sensitive LB film and organic vapours was obtained using F-R diagram. And the position of each organic vapour were different as to the kind and injection amount. Thus F-R diagram can be applied to one-channel gas sensor using the QCA and useful to analyze the response mechanism between organic vspours and sensitive LB films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.208-208
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• 2009

We used Brewster's Law to examine the mechanism of liquid crystal (LC) alignment on an organic insulation layer when subjected to ion-beam irradiation. Brewster's Law implies that the maximum rate polarized ray on a slanted insulation layers on the substrate and it illustrates the dependence of polarization and themechanical structure on the ion beam irradiation process. The pretilt angle of nematic LCs on the organic insulation surface was about $1.13^{\circ}$ for an ion beam exposure of $45^{\circ}$ for 1 minute at 1800eV. This shows the dependence of LC alignment on the polarization ratio in a slanted organic insulation layer.