• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.168-169
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• 2007

Organic transistors are promising in the future development of active devices for flexible, low-cost and large-area photoelectric devices. However, conventional organic field-effect transistors have lowspeed, low-power, and relatively high operational voltage. Vertical type transistors show high-speed and high-current characteristics and are suitable for driver elements of flexible displays.

• 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.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.91-93
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• 2008

The organic field-effect transistors with step-edge structure were fabricated. Source and drain electrodes were obliquely deposited by vacuum evaporation. The step-edge of the gate electrode serve as a shadow mask, and the short channel is formed at the step-edge. The excellent device performances were obtained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.12
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• pp.1009-1013
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• 2009

In this study, we have been synthesized the dielectric layer using pure organic and organic-inorganic hybrid precursor on flexible substrate for improving of the organic thin film transistors (OTFTs) and, design and fabrication of organic thin-film transistors (OTFTs) using small-molecule organic semiconductors with pentacene as the active layer with record device performance. In this work OTFT test structures fabricated on polymerized substrates were utilized to provide a convenient substrate, gate contact, and gate insulator for the processing and characterization of organic materials and their transistors. By an adhesion development between gate metal and PI substrate, a PI film was treated using $O_2$ and $N_2$ gas. The best peel strength of PI film is 109.07 gf/mm. Also, we have studied the electric characteristics of pentacene field-effect transistors with the polymer gate-dielectrics such as cyclohexane and hybrid (cyclohexane+TEOS). The transistors with cyclohexane gate-dielectric has higher field-effect mobility, $\mu_{FET}=0.84\;cm^2/v_s$, and smaller threshold voltage, $V_T=-6.8\;V$, compared with the transistor with hybrid gate-dielectric.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1279-1282
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• 2008

Organic field effect transistors are excellent candidates for addressing and local amplification elements for large area electronics because they can easily be processed at low temperatures on essentially arbitrary substrates. We present the use of these devices in an active matrix photodetector and as a buffer for a strain sensor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.164-168
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• 2005

We report high performance poly (3-hexylthiophene) organic field-effect transistors fabricated on a plastic substrate. The polymer active channel layer was directly printed by the rubber stamp printing method with a pre-patterned elastomer stamp. As a result. organic transistors having average field-effect mobility of 0.079 $cm^2/Vs$ and on/off ratio of $10^4{\sim}10^5$ were realized on a plastic substrate. Also, through the investigation of the molecular ordering of rubber-stamp-printed poly (3-hexylthiophene) films using synchrotron grazing-incidence X-ray diffraction measurements, the films were found to have edge-on structure which is favorable in realizing high performance organic transistors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.598-601
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• 1999

There is currently considerable interest in the applications of conjugated polymers, oligomers and small molecules for thin-film electronic devices. Organic materials have potential advantages to be utilized as semiconductors in field effect transistor and light emitting didoes. In this study, Pentacene thin film transistors(TFTs) were fabricated on glass substrate. Aluminum and Gold wei\ulcorner used fur the gate and source/drain electrodes. Silicon dioxde was deposited as a gate insulator by PECVD and patterned by R.I.E. The semiconductor layer of pentacene was thermally evaporated in vaccum at a pressure of about 10$^{-8}$ Torr and a deposition rate 0.3$\AA$/sec. The fabricated devices exhibited the field-effect mobility as large as 0.07cm$^2$/Vs and on/off current ratio larger than 10$^{7}$

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.632-632
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• 2013

We generated single-crystal organic nanowire arrays 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. The position of the nanowires on complex structures is easy to adjust, because the mold is movable on the substrates before the polar liquid layer, which acts as an adhesive lubricant, is dried. Repeated application of the direct printing process can be used to produce organic nanowire-integrated electronics with twoor 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.10
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• pp.665-671
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• 2017

Herein, we report the fabrication of low-voltage N-type organic field-effect transistors by using high capacitance fluorinated polymer gate dielectrics such as P(VDF-TrFE), P(VDF-TrFE-CTFE), and P(VDF-TrFE-CFE). Electron-withdrawing functional groups in PVDF-based polymers typically cause the depletion of negative charge carriers and a high contact resistance in N-channel organic semiconductors. Therefore, we incorporated intermediate layers of a low-k polymerto prevent the formation of a direct interface between PVDF-based gate insulators and the semiconducting active layer. Consequently, electron depletion is inhibited, and the high charge resistance between the semiconductor and source/drain electrodes is remarkably improved by the in corporation of solution-processed charge injection layers.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.137-140
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• 2007

We prepared ambipolar organic field-effect transistors and observed blue emission when both hole and electron accumulation layers were in the channel. We found that the reduction of carrier traps and controlling devices' preparation and measurement conditions were crucial for ambipolar operation.