• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.191-191
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• 2007

By employing a photo-sensitive PVA as a photoresist, we first demonstrated simultaneous patterning and passivation of P3HT active layer. The passivation layers were obtained by annealing the organic layers after developing PVA and over-etching the P3HT layer. The fabricated OTFTs were electrically characterized. The OTFTs after the passivation exhibited the field-effect of ${\sim}5.9{\times}10^{-4}cm^2/V{\cdot}s$, on/off current ratio of ${\sim}10^3$. The value of OTFTs a little degradation with time in air but it appeared different unpassivated OTFT.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.176-176
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• 2010

One of the critical issues for applications of flexible organic thin film transistors (OTFTs) for flexible electronic systems is the electrical stabilities of the OTFT devices, including variation of the current on/off ratio (Ion/Ioff), leakage current, threshold voltage, and hysteresis under repetitive mechanical deformation. In particular, repetitive mechanical deformation accelerates the degradation of device performance at the ambient environment. In this work, electrical stability of the pentacene organic thin film transistors (OTFTs) employing multi-stack hybrid encapsulation layers was investigated under mechanical cyclic bending. Flexible bottom-gated pentacene-based OTFTs fabricated on flexible polyimide substrate with poly-4-vinyl phenol (PVP) dielectric as a gate dielectric were encapsulated by the plasma-deposited organic layer and atomic-layer-deposited inorganic layer. For cyclic bending experiment of flexible OTFTs, the devices were cyclically bent up to 105 times with 5mm bending radius. In the most of the devices after 105 times of bending cycles, the off-current of the OTFT with no encapsulation layers was quickly increased due to increases in the conductivity of the pentacene caused by doping effects from $O_2$ and $H_2O$ in the atmosphere, which leads to decrease in the Ion/Ioff and increase in the hysteresis. With encapsulation layers, however, the electrical stabilities of the OTFTs were improved significantly. In particular, the OTFTs with multi-stack hybrid encapsulation layer showed the best electrical stabilities up to the bending cycles of $10^5$ times compared to the devices with single organic encapsulation layer. Changes in electrical properties of cyclically bent OTFTs with encapsulation layers will be discussed in detail.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1312-1314
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• 2007

The effect of gate insulator surface treatment on electrical characteristics of bottom contact (BC) and suspended source/drain (SSD) organic thinfilm transistors (OTFTs) was studied. Triisopropylsilylethynyl pentacene was used as an active material and was printed by ink-jet printing method. In case of the BC OTFTs, threshold voltage was shifted from positive to near zero, and the fieldeffect mobility was increased when the gate insulator surface was treated with hexamethyldisilazane. However, in case of SSD OTFT, threshold voltage shift was not observed and the field-effect mobility was decreased.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1276-1279
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• 2005

The long-term stability of pentacene thin-film transistors (TFTs) encapsulated with a transparent $SnO_2$ thin-film prepared by ion beam assisted deposition (IBAD) was investigated. With a buffer layer of thermally evaporated 100 nm $SnO_2$ film deposited prior to IBAD process, our encapsulated OTFTs sustained its initial field-effect mobility up to one month and then gradually degraded showing only 37% reduction compared to 90% reduction of non-encapsulated OTFTs after 100 days in air ambient. The encapsulated OTFTs also exhibited superior on/off current ratio of over $10^5$ to that of the unprotected devices $({\sim}10^4)$ which was reduced from ${\sim}10^6$ before aging. Therefore, the enhanced long-term stability of our encapsulated OTFTs should be attributed to well protection of permeation of $H_2O$ and $O_2$ into the devices by the IBAD $SnO_2$ thin-film which could be used as an effective inorganic gas barrier for transparent organic electronic devices.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1310-1312
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• 2005

Passivation of organic thin-film transistors (OTFTs) using organic and metal thin-film was presented. Parylene-C and titanium were used as an organic and metal layer, respectively. With the proposed passivation method the degradation of electric parameters of OTFTs was relieved compared with non-passivated devices. Several electric parameters such as on/off current, field-effect mobility, and threshold voltage were shown.

• 한국재료학회지
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• 제15권3호
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• pp.202-208
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• 2005

The surface states of gate dielectrics affect device performance severely in Pentacene OTFTs. We have fabricated organic thin-film transistors (OTFTs) using pentacene as an active layer with chemically modified $SiO_2$ gate dielectrics. The effects of the surface treatment of $SiO_2$ on the electric characteristics of OTFTS were investigated. The surface of $SiO_2$ gate dielectric was treated by normal wet cleaning process, $O_2-plasma$ treatment, hexamethyldisilazane (HMDS), and octadecyltrichlorosilane (OTS) treatment. After the surface treatments, the contact angles and surface free energies were measured in order to analyze the surface state changes. In the electrical measurements, typical I-V characteristics of TFTs were observed. The field effect mobility, $\mu$, was calculated to be $0.29\;cm^2V^{-1}s^{-1}$ for OTS treated sample while those for the HMDS, $O_2$ plasma treated, and wet-cleaned samples were 0.16, 0.1, and $0.04\;cm^2V^{-1}s^{-1}$, respectively.

• 한국전기전자재료학회논문지
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• 제16권11호
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• pp.961-968
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• 2003

In order to reach the high electrical quality of organic thin film transistors (OTFTs) such as high mobility and on-off current ratio, it is strongly desirable to study the enhancement of electrical properties in OTFTs. Here, we report the novel method of hydrogen plasma treatment to improve electrical properties in inverted staggered OTFTs based on pentacene as active layer. To certify the effect of this method, we compared the electrical properties of normal device as a reference with those of device using the novel method. In result, the normal device as a reference making no use of this method exhibited a field effect mobility of 0.055 $\textrm{cm}^2$/Vs, on/off current ratio of 10$^3$, threshold voltage of -4.5 V, and subthreshold slope of 7.6 V/dec. While the device using the novel method exhibited a field effect mobility of 0.174 $\textrm{cm}^2$/Vs, on/off current ratio of 10$\^$6/, threshold voltage of -0.5 V, and subthreshold slope of 1.49 V/dec. According to these results, we have found the electrical performances in inverted staggered pentacene TFT owing to this method are remarkably enhanced. So, this method plays a key role in highly improving the electric performance of OTFTs. Moreover, this method is the first time yet reported for any OTFTs.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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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.

• 한국전기전자재료학회논문지
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• 제25권7호
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• pp.531-536
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• 2012

We herein present results of flat and uniform polymer-blended small molecular semiconductor thin films. Which were produced for organic thin film transistors (OTFTs), using a simple pre-metered horizontal dipping process. The organic semiconducting thin films were composed of 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-PEN) composite blended with a polymer binder of poly(${\alpha}$-methylstyrene) (PaMS). We show that the pre-metered horizontal-dip-coating(H-dip-coating) process allowed the critical control of the thickness of the blended TIPS-PEN:PaMs thin film. The fabricated OTFTs using the TIPS-PEN:PaMs films exhibited maximum field-effect mobility of $0.22\;cm^2\;V^{-1}\;s^{-1}$. These results demonstrated that H-dip-coated TIPS-PEN:PaMS films show considerable promise for the production of reliable, reproducible, and high-performance OTFTs.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.119-122
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• 2008

In this paper, we describe the current status and issues of the oxide thin-film transistors (OTFTs), which attract much attention as an emerging new backplane technology replacing conventional silicon-based TFTs technologies. First, the unique benefits of OTFTs will be presented as a backplane for large-sized AMOLED including note-book PC, second TV and HD-TV. And then, the state-of-the-art transistor performance and uniformity characteristics of OTFTs will be highlighted. The obtained a-IGZO TFTs exhibited the field-effect mobility of $18\;cm^2/Vs$, threshold voltage of 1.8 V, on/off ratio of $10^9$, and subthreshold gate swing of 0.28 V/decade. In addition, the world largest-sized 12.1-inch WXGA active-matrix organic light emitting diode (AMOLED) display is demonstrated using indium-gallium-zinc oxide (IGZO) TFTs.