Direct Photo-Patternable Organic-Inorganic Hybrid Gate Dielectric for Organic Thin-Film Transistors: Influence of the ZrO2 Content

Seong Hui Lee,정선호,Jun Kwang Song,문주호 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.2

An inorganic-organic hybrid gate dielectric was synthesized in a sol-gel reaction. 3-methacry loxypropyltrimethoxysilane serves as both an organosiloxane network former and an organic func- tional group whose photo-polymerization can permit negative-type photo-patternability. Addition of zirconium alkoxide leads to the uniform incorporation of ZrO2 distributed in the matrix phase. At 170℃, the obtained hybrid dielectric exhibits a smooth surface structure with an RMS roughness of ~0.25 nm. The dielectric strength of the film was determined to be 1.2~2.3 MV/cm. Increasing the amount of zirconium alkoxide effectively enhances the dielectric constant of the hybrid films from 5.3 to 6.6. The use of the gate dielectric with a high dielectric constant proves to be beneficial for fabricating an organic thin-film transistor. The organic thin-film transistor fabricated using the hybrid dielectric with a high dielectric constant shows a very low threshold voltage close to ~0.4 V without deteriorating carrier mobility. An inorganic-organic hybrid gate dielectric was synthesized in a sol-gel reaction. 3-methacry loxypropyltrimethoxysilane serves as both an organosiloxane network former and an organic func- tional group whose photo-polymerization can permit negative-type photo-patternability. Addition of zirconium alkoxide leads to the uniform incorporation of ZrO2 distributed in the matrix phase. At 170℃, the obtained hybrid dielectric exhibits a smooth surface structure with an RMS roughness of ~0.25 nm. The dielectric strength of the film was determined to be 1.2~2.3 MV/cm. Increasing the amount of zirconium alkoxide effectively enhances the dielectric constant of the hybrid films from 5.3 to 6.6. The use of the gate dielectric with a high dielectric constant proves to be beneficial for fabricating an organic thin-film transistor. The organic thin-film transistor fabricated using the hybrid dielectric with a high dielectric constant shows a very low threshold voltage close to ~0.4 V without deteriorating carrier mobility.

Enhanced Performance of Solution-Processed Organic Thin-Film Transistors with a Low-Temperature-Annealed Alumina Interlayer between the Polyimide Gate Insulator and the Semiconductor

Yoon, Jun-Young,Jeong, Sunho,Lee, Sun Sook,Kim, Yun Ho,Ka, Jae-Won,Yi, Mi Hye,Jang, Kwang-Suk American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.11

<P>We studied a low-temperature-annealed sol–gel-derived alumina interlayer between the organic semiconductor and the organic gate insulator for high-performance organic thin-film transistors. The alumina interlayer was deposited on the polyimide gate insulator by a simple spin-coating and 200 °C-annealing process. The leakage current density decreased by the interlayer deposition: at 1 MV/cm, the leakage current densities of the polyimide and the alumina/polyimide gate insulators were 7.64 × 10<SUP>–7</SUP> and 3.01 × 10<SUP>–9</SUP> A/cm<SUP>2</SUP>, respectively. For the first time, enhancement of the organic thin-film transistor performance by introduction of an inorganic interlayer between the organic semiconductor and the organic gate insulator was demonstrated: by introducing the interlayer, the field-effect mobility of the solution-processed organic thin-film transistor increased from 0.35 ± 0.15 to 1.35 ± 0.28 cm<SUP>2</SUP>/V·s. Our results suggest that inorganic interlayer deposition could be a simple and efficient surface treatment of organic gate insulators for enhancing the performance of solution-processed organic thin-film transistors.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-11/am400996q/production/images/medium/am-2013-00996q_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am400996q'>ACS Electronic Supporting Info</A></P>

유기반도체를 이용한 양극성 유기박막 트랜지스터

김강대,조신욱 한국물리학회 2013 새물리 Vol.63 No.1

Organic semiconducting materials have received immense attention as active materials for future flexible optoelectronic devices because of their optical and electrical properties, which are like those of a conventional metal or semiconductor, as well as their mechanical advantage and processibility, which are commonly associated with conventional plastic materials. Particularly, organic ambipolar thin film transistors, which integrate both p-type and n-type channels in one device and thereby simplify circuit design and fabrication processes, are particularly attractive for use in low-cost,flexible, and portable electronic applications. In this article, we will introduce the device structure and the operation principles of organic ambipolar thin film transistors. In addition, some technical approaches to enhance performance of organic ambipolar thin film transistors, such as post-thermal annealing and processing additive method, will be introduced. Finally, organic ambipolar thin film transistors that are fabricated with a single material and show equivalent bipolar transport properties will be introduced. 유기 박막 트랜지스터 (OTFT)는 제작 공정이 간단하고 비용이 저렴하다는장점과 더불어 유기 반도체 자체가 가지는 가공성, 유연성 등으로 인해유연한 (flexible) 전자기기를 구현 할 수 있다는 가능성으로 미래형전자기기의 핵심 구동 소자로서 많은 관심을 받고 있다. 특히, 한소자에서 p형과 n형이 동시에 구현되는 양극성 OTFT는 구동 회로의 설계및 제작 공정을 단순화 시키고 다양한 기능을 부가 시킬 수 있어 좀 더경량화, 소형화된 미래형 전자 기기를 구현 할 수 있도록 해준다. 본논문에서는 이러한 양극성 OTFT의 구조 및 구동 원리를 개괄적으로소개하고 양극성 OTFT의 구현을 위해 필요한 소재와 소자 구현 기술에대해서 살펴보았다. 먼저 양극성 OTFT의 구현을 위해 현재 가장 폭넓게활용되는 이종 복합체를 활용한 기술을 소개하고 동 소자에서 전하의이동도를 높이기 위한 후 열처리법과 첨가제를 이용한 화학적 방법 등을설명하고, 더불어 최근에 보고된 양극성 성질을 가지는 단일 물질을이용한 양극성 OTFT에 대해 알아보고자 한다.

Macroporous organic thin film using small-molecule heterointerface for high-performance organic-transistor-based chemical sensors

장문정,강보석,정윤영,김혜나,곽상규,조길원,오준학 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

The semiconductor-dielectric interface significantly affects the performance and the reliability of field-effect transistors. Controlling this interface is an important issue to improve device performance in the organic electronics community. Here we report an approach that utilizes an organic heterointerface to improve the crystallinity and control the morphology of an organic thin film. Pentacene is used as an active layer above, and m-bis(triphenylsilyl)benzene (TSB3) is used as the bottom layer. Sequential evaporations of these materials result in high-quality organic thin films with indistinct grain boundaries and nanometre-sized pores. The pentacene film exhibits high mobility, and the pore-rich structure improves the sensitivity of organic-transistor-based chemical sensors.

Synthesis and Characterization of Fluorene Derivatives as Organic Semiconductors for Organic Field-Effect Transistor

윤채영,서성용 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

We have synthesized and characterized fluorene derivatives with alkylated thiophene as solution-processed organic semiconductors for organic field-effect transistor. HOMO/LUMO energy levels of the developed materials were tuned via different electron-acceptors. Organic field-effect transistor fabricated from dicyanovinylene-functionalized fluorine derivative with octyl thiophene as the side group exhibited n-channel characteristic with electron mobility of 0.0055 cm2/V·s and current on/off ratio ~106. Film surface morphology and texture were correlated with the corresponding device performance.

Solution-Based Direct Growth of Organic Crystals on an Active Channel Region for Printable Bottom-Contact Organic Field-Effect Transistors

Hong, Jung-Pyo,Lee, Seonghoon WILEY-VCH Verlag 2009 Angewandte Chemie Vol.48 No.17

<P>The growth and self-organization of organic crystals between a source (S) and drain (D) electrode by a method based on the use of a micropipette and isothermal evaporation of the solvent in a two-liquid system led to the formation of organic-crystal transistors (see polarized optical micrograph). The method is similar to ink-jet printing and should be suitable for the fabrication of low-cost and mass-producible printed electronic devices. <img src='wiley_img/14337851-2009-48-17-ANIE200805971-content.gif' alt='wiley_img/14337851-2009-48-17-ANIE200805971-content'> </P> <B>Graphic Abstract</B> <P>The growth and self-organization of organic crystals between a source (S) and drain (D) electrode by a method based on the use of a micropipette and isothermal evaporation of the solvent in a two-liquid system led to the formation of organic-crystal transistors (see polarized optical micrograph). The method is similar to ink-jet printing and should be suitable for the fabrication of low-cost and mass-producible printed electronic devices. <img src='wiley_img/14337851-2009-48-17-ANIE200805971-content.gif' alt='wiley_img/14337851-2009-48-17-ANIE200805971-content'> </P>

Photocrosslinkable zinc diacrylate-based gate insulators for reliable operation of organic thin film transistors

Rho, Hyun Yeol,An, Tae Kyu,Baek, Seolhee,Park, So Hyun,Lee, Jihoon,Han, Sung Soo,Lee, Hwa Sung,Kim, Se Hyun Elsevier 2018 Organic electronics Vol.59 No.-

<P><B>Abstract</B></P> <P>We report new organic-inorganic hybrid gate insulator materials containing solution-processable zinc diacrylate (ZnDA) and dipentaerythritol penta-/hexa-acrylate (DPHA) to fabricate high-performance and reliable organic thin film transistors (OTFTs). ZnDA-DPHA organic-inorganic hybrid materials can be crosslinked by ultraviolet illumination (<I>λ</I> <SUB>max</SUB> = 365 nm) within 7 min in the presence of a photoinitiator. Hence, the crosslinked insulator film provides not only good insulating properties (such as a dielectric constant of ca. 4.95 and low leakage current of <2 × 10<SUP>−7</SUP> A/cm<SUP>2</SUP> at 2 MV/cm) but also surface properties that can induce good semiconductor growth. Consequently, pentacene-based OTFTs employing the crosslinked ZnDA-DPHA gate insulators showed good electrical performance and reliable device operation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The development of photo-crosslinkable organic-inorganic hybrid gate insulator materials. </LI> <LI> The optimization of the photocrosslinking reaction to fabricate the insulator suitable for high-performance and reliable OTFTs. </LI> <LI> OTFT employing crosslinked ZnDA-DPHA insulator displayed reliable device operation with <I>μ</I> <SUB>FET</SUB> up to 0.33 cm<SUP>2</SUP>/Vs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Synthesis and Characterization of Fluorenone-Based Donor-Acceptor Small Molecule Organic Semiconductors for Organic Field-Effect Transistors

윤채영,서성용 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

In this study, a series of new fluorenone-based small molecules were synthesized and characterized as organic semiconductors for organic field-effect transistors. Thermal, optical, and electrochemical properties of the new compounds were characterized. Furthermore, thin films of the developed compounds were employed as organic semiconductors, and vacuum-deposited film of fluorenone derivative with alkylated double thiophene exhibited p-channel device characteristics with hole mobility as high as 0.02 ㎠/V·s and current on/off ratio of 107. In addition, surface morphology and microstructure of vacuum deposited films were analyzed and correlated with the electrical characteristics.

Facile polymer gate dielectric surface-modification for organic thin-film transistors using self-assembled surfactant layer

Yu, Seong Hoon,Cho, Jangwhan,Ha, Jae Un,Chung, Dae Sung Elsevier 2017 Organic electronics Vol.41 No.-

<P><B>Abstract</B></P> <P>We demonstrate facile polymer gate dielectric surface-modification method for organic thin-film transistors (OTFTs). We simply introduce self-assembled surfactant layer onto the top surface of poly(4-vinylphenol) (PVP) dielectric by spin coating PVP solution mixed with sodium dodecyl sulfate and tridecafluorohexane-1-sulfonic acid potassium salt as additive agents. The surfactant-modified PVP layer acquires various merits compared to pristine PVP layer in terms of surface smoothness and hydrophobicity, as confirmed by contact angle measurement, atomic force microscopy analyses, grazing incident X-ray diffraction and near-edge X-ray absorption fine structure spectroscopy. The resulting OTFTs with the conventional semiconducting poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) as the active layer and surfactant-modified PVP as the dielectric layer reveal overall ascendency over the OTFT with pristine PVP, especially in terms of operating hysteresis and reliability. The effects of hydrophobicity of surfactants on the surface properties of PVP as well as the OTFT performances are fully discussed in conjunction with various characterization tools.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We demonstrate facile polymer gate dielectric surface-modification method for organic thin-film transistors. </LI> <LI> We introduce self-assembled surfactant layer onto the top surface of PVP dielectric. </LI> <LI> The surfactant-modified PVP acquires merits compared to pristine PVP in terms of surface smoothness and hydrophobicity. </LI> <LI> X-ray study supports the superiority of surfactant-modified PVP and proved the tendency of agglomeration of semiconductor. </LI> <LI> The surfactant-modified PVP show overall ascendency over the OTFT with pristine PVP in terms of hysteresis and reliability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Versatile threshold voltage control of OTFTs via discontinuous pn-heterojunction formation

Cho, B.,Yu, S.H.,Lee, M.H.,Lee, J.,Lee, J.Y.,Cho, J.H.,Kang, M.S. Elsevier Science 2014 ORGANIC ELECTRONICS Vol.15 No.12

We demonstrate the versatility of the threshold voltage control for organic thin-film transistors (OTFTs) based on formation of discontinuous pn-heterojunction on the active channel layer. By depositing n-type dioctyl perylene tetracarboxylic diimide molecules discontinuously onto base p-type pentacene thin films (the formation of the discontinuous pn-heterojunction), a positive shift of the threshold voltage was attained which enabled realizing a depletion-mode transistor from an original enhancement-mode pristine pentacene transistor. Careful control of the threshold voltage based on this method led assembling a depletion-load inverter comprising a depletion-mode transistor and an enhancement-mode transistor connected in series that yielded tunable signal inversion voltage approaching 0V. In addition, the tunability could be applied to improve the program/erase signal ratio for non-volatile transistor memories by more than 4 orders of magnitude compared to reference memory devices made of pristine pentacene transistors.