• Journal of the Korean Applied Science and Technology
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• v.27 no.1
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• pp.44-49
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• 2010

본 논문에서는 6,13-bis (triisopropylsily lethynyl)-pentacene (TIPS-pentacene) 유기 박막 트랜지스터에 니켈 버퍼층을 적층했을 때의 효과를 연구하였다. 니켈 (Nickel) / 은(Silver) 소스 드레인 전극은 은 (Silver) 전극이 단독으로 쓰일 때 보다 에너지 레벨차이를 줄여 캐리어의 주입이 더 잘되도록 도와주므로써 전기적 특성을 향상 시켜준다. 또한 유기 게이트 절연체의 추가로 TIPS-pentacene 은 규칙적 배열된 형태를 가지므로써 소자 성능의 향상을 가지고 온다. 제작한 유기박막트랜지스터 에서 $0.01\;cm^2$의 포화영역 이동도를 얻을 수 있었으며, 또한 드레인 전압을 50 V로 하고 게이트 전압을 20 V에서 -50 V 까지 인가하였을 때 $2{\times}10^4$의 전멸 비를 얻을 수 있었다. 이러한 결과를 polyethylene terephthalate (PET) 기판을 이용한 유연한 OTFTs 에 적용시켜본 결과 유리기판위에 제작했을 때와 비슷한 성능을 얻음을 확인하였다.

• Journal of Information Display
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• v.12 no.4
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• pp.199-203
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• 2011

Reported herein is the film morphology control of inkjet-printed 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) organic thin-film transistors for the improvement of their performance and of the device-to-device uniformity. The morphology of the inkjetted TIPS-pentacene films was significantly influenced by the bank geometry such as the bank shapes and confinement area for the channel region. A specific confinement size led to the formation of uniform TIPS-pentacene channel layers and better electrical properties, which suggests that the ink volume and the solid concentration of the organic-semiconductor solutions should be considered in designing the bank geometry.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.937-939
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• 2009

In this paper, we report electrical properties of OTFTs made by ink-jet printing with polyvinylphenol (PVP) for bank layer and bis(triisopropylsilylenthynyl) pentacene (TIPS-pentacene) for semiconductor. We could achieve better crystallization and surface uniformity of TIPS pentacene by employing PVP bank layer. The OTFT with PVP bank layer exhibited an field-effect mobility of 0.18 $cm^2$/Vs, current on/off ratio of $2.09{\times}10^5$, and subthreshold slope of 0.42 V/decane.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.11
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• pp.992-998
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• 2009

We investigated the influence of organic solvents on the droplet properties of 6,13-bis (triisopropylsilylethynyl) pentacene (TIPS-pentacene), which was used for semiconductor of organic thin film transistors (OTFTs) and deposited by ink jet printing. From the result of the investigation, the conditions of a suitable solvent is that boiling point should be above $200^{\circ}C$ to reduce coffee stain and the surface tension above 32 dyn/cm to decrease the droplet size. Consequently, we selected tetralin which have a high boiling point ($207^{\circ}C$) and high surface tension (34.3 dyn/cm) as the solvent for TIPS-pentacene, and applied it to OTFTs. In fabrication process the conventional bank process employing photolithography and etching process was replaced by ink jet printed bank process, resulting in simplifying the process. Especially, polyvinylphenol was used for the bank, and the high hydrophobicity could improve the confinement of TIPS molecules inside the bank, enhancing the performance over the conventional hydrophilic polyvinylalcohol bank. The mobility was $0.18\;cm^2/Vs$, current on/off ratio $2.09{\times}10^5$, subthreshold slope 0.42 V/dec, and off state current $0.049\;pA/{\mu}m$.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.284-284
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• 2010

We report a fabrication of 6, 13-bis(triisopropylsilylethynyl) (TIPS) pentacene nanowires that made on Si substrates by liquid bridge-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 TIPS-pentacene nanowire and the Si substrate. The patterned TIPS-Pentacene nanowires have been investigated by Atomic force microscopy (AFM), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and electrical properties.

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.6
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• pp.468-471
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• 2013

In this paper, we analyzed the effects of the number of TIPS-pentacene droplets and also the substrate temperature on the performance of OTFTs. As the number of the droplets increased, the mobility increased and reached the peak value and then reduced at the all temperatures. The peak mobility was $0.14{\pm}0.03cm^2/V{\cdot}sec$ at 3 droplets and $41^{\circ}C$, $0.19{\pm}0.02cm^2/V{\cdot}sec$ at 4 droplets and $46^{\circ}C$, and $0.35{\pm}0.10cm^2/V{\cdot}sec$ at 7 droplets and $51^{\circ}C$. The reason of existence of peak mobility can be found in matching the evaporation of solvent with the velocity of crystal formation. When two parameters were properly matched, the mobility produced the highest.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1150-1153
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• 2006

In this paper, we investigated the effect of solvent on electrical properties of triisopropylsilyl (TIPS) pentacene organic thin-film transistors (OTFTs). The TIPS pentacene was spin coated by using chlorobenzene, p-xylene, chloroform and toluene as solvent. Fabricated OTFT with chlorobenzene showed field-effect mobility of $0.01\;cm^2/V{\cdot}s$, on/off ratio $4.3{\times}10^3$ and threshold voltage of 5.5 V. In contrast, with chloroform the mobility was $5.8{\times}10^{-7}\;cm^2/Vs$, on/off ratio $1.1{\times}10^2$ and threshold voltage of 1.7 V.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1135-1138
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• 2006

By ink-jet printing method, organic thin-film transistors (OTFTs) having soluble 6,13-bis (triisopropylsilylethynyl) pentacene (TIPS pentacene) as an active material were fabricated. The TIPS pentacene solution was made with chlorobenzene and anisole. The solutions were printed on poly (4-vinylphenol) (PVP) dielectric layers and source/drain electrodes by piezo-type heads for bottom contact OTFTs. The dielectric layers had untreated or HMDS-treated conditions. The chlorobenzene device showed the highest field effect mobility of $0.016\;cm^2/Vs$ and the anisole HMDS-treated device shows the highest $I_{on}/I_{off}$ ratio of $10^5$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.379-379
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• 2013

본 논문에서는 Normal ink jetting 공법으로 OTFT를 제작할 때 coffee stain effect에 의해서 반도체 소자의 특성이 저하되는 것을 극복하기 위해서 동일한 위치에 동일한 부피로 Droplet을 형성하는 Multiple ink jetting 공법을 통해 TIPS pentacene 결정의 Morphology와 전기적 특성이 어떻게 변화하는지 알아 보았다. Multiple ink jetting의 drop 횟수가 증가할수록 coffee stain effect에 의해서 형성된 가운데 영역의 Dendrite grain이 점점 작아지다가 7 Drops 이후로는 Big grain 만 남게 되었다. Active layer의 표면 Roughness는 drop 횟수가 증가할수록 낮아지다가 일정 count 이후로는 다시 높아지는 것을 확인할 수 있었다. 전계 이동도(mobility)는 drop 횟수가 증가할수록 커지다가 일정 count 이후로는 saturation되는 것을 확인할 수 있었다. Multiple ink jetting에 의해서 만들어진 OTFT 소자의 전계 이동도(mobility)는 1 drop과 10 drops에서 각각 0.0059, 0.036 cm2/Vs 로 6배 정도 차이가 있었다. 이것은 첫 drop에 의해 만들어진 가운데 Dendrite grain 영역이 Multiple ink jetting을 반복하면서 점점 작아지게 되어 사라지고 두꺼운 Grain 영역만 남게 된 것으로 판단된다. Vth 와 On/Off ratio는 1 drop과 10 drops에서 각각 -3 V, -2 V 그리고 $3.3{\times}10^3$, $1.0{\times}10^4$를 보였다. OTFT의 substrate로 Flexible한 polyethersulfone (PES) 기판을 사용하였고, 절연체로 Spin coating된 Poly-4-vinylphenol (PVP)가 사용되었으며, Gate 및 Source/Drain 전극은 Au를 50 nm 두께로 증착하였다. Channel의 width와 length는 각각 100 um, 40 um 였고, Gate 전극 위에 Active layer를 형성한 Bottom gate 구조로 제작되었다. Ink jet으로 제작된 TIPS pentacene의 결정성은 x-ray diffraction (XRD)와 광학 현미경으로 분석하였고 Thickness profile은 알파스텝 측정기를 이용하였으며, OTFT의 전기적 특성은 Keithley-4,200을 사용하여 측정하였다.