Electrical Characterization of Pentacene-Based Organic Thin-Film Transistors

박동규,허진희,권정민,정일섭 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.2

Organic thin-film transistors were formed on a pentacene active layer by using a back gate structure. Transistors were fabricated either on a patterned pentacene film or on a blank pentacene film to understand device performance in terms of pentacene film coverage. We found that the surface free energy of SiO2 was closely related to the grain features in the pentacene film, affecting the leakage current level. The current flow path was identied by comparing topologies with current images. In the pentacene film, the current ows through grains rather than along the pentacene grain boundaries. The patterned pentacene thin-film transistor formed on dry oxidized SiO2 showed better electrical properties in terms of mobility, on/off ratios and subthreshold swing. Organic thin-film transistors were formed on a pentacene active layer by using a back gate structure. Transistors were fabricated either on a patterned pentacene film or on a blank pentacene film to understand device performance in terms of pentacene film coverage. We found that the surface free energy of SiO2 was closely related to the grain features in the pentacene film, affecting the leakage current level. The current flow path was identied by comparing topologies with current images. In the pentacene film, the current ows through grains rather than along the pentacene grain boundaries. The patterned pentacene thin-film transistor formed on dry oxidized SiO2 showed better electrical properties in terms of mobility, on/off ratios and subthreshold swing.

Novel Preparation Route of Conductive PPy-PAN Hybrid Thin Films Using Simultaneous Co-vaporized Vapor Phase Polymerization

Pauline May Losaria,Jin-Heong Yim(임진형) 한국고분자학회 2018 폴리머 Vol.42 No.4

본 연구에서 서로 다른 중합 메커니즘을 가진 두 개의 단량체(즉, 산화 커플링 중합과 라디칼 중합)를 동시에 공-증발 기상 중합(SC-VPP) 수행하여 유기-유기 전도성 복합 박막을 제조하는 새로운 접근법을 보고한다. SC-VPP 공정을 통해 폴리피롤(PPy)과 폴리아크릴로니트릴(PAN)로 구성된 PPy-PAN 복합 박막을 제조하였다. 두 종류의 유기-유기 전도성 복합 박막의 제조는 FTIR 및 <SUP>1</SUP>H NMR 분석을 통해 확인되었다. PPy-PAN 박막은 입자 크기가 작고 PPy 박막보다 상대적으로 매끄러운 표면을 가졌다. PPy-PAN은 부드러운 표면 형태로 인해 PPy와 유사한 전기전도성을 보였다. PPy-PAN의 접촉각은 30° 이하로 표면 특성을 친수성으로 조절하였다. 본 고에서 제안된 SCVPP기반 전도성 하이브리드 박막 소재의 개질 기술로 다양한 디바이스 계면에서의 특성을 조절가능하리라 기대한다. A new approach for the fabrication of organic-organic conducting composite thin films using simultaneous covaporization vapor phase polymerization (SC-VPP) of two monomers that have different polymerization mechanisms (i.e., oxidation-coupling polymerization and radical polymerization) has been reported for the first time. In this study, a PPy-PAN composite thin film consisting of polypyrrole (PPy) and polyacrylonitrile (PAN) were prepared by the SC-VPP process. The preparation of the two types of organic-organic conductive composite thin films was confirmed through FTIR and <SUP>1</SUP>H NMR analysis. The PPy-PAN thin film had a smaller grain size and relatively smoother surface than the PPy thin film. PPy-PAN showed similar electrical conductivity to PPy due to its smooth surface morphology. The contact angle of PPy-PAN was below 30°, which means the surface property was changed to hydrophilic character. The proposed SC-VPP-based hybrid materials allow for control of the surface properties, such as hydrophilicity, of the resulting thin films.

Slot-die coating of organic thin films for active-matrix organic light-emitting diode displays

Shin, Dongkyun,Lee, Jin-Young,Hong, Ki-Young,Park, Jongwoon,Seo, Yu-Seok Elsevier 2016 THIN SOLID FILMS - Vol.619 No.-

<P><B>Abstract</B></P> <P>We investigate solution coating of organic thin films for the fabrication of active-matrix organic light-emitting diode (AMOLED) displays. For blanket layers, an aqueous polymer-based hole injection layer (HIL) and non-aqueous polymer-based hole transport layer (HTL) are fabricated by slot-die coating and also by spin coating for comparison. Thin organic films coated on a substrate with a pixel-defining layer (bank) exhibit the concave profile due to capillary rise. With an attempt to suppress it and thus obtain thin films with high conformity, we carry out solution coating by varying the pixel size, solvent, and drying condition. As the pixel size increases, the overall film thickness increases by an enhancement in the filling of a solution into the cells. We have found that spin coating provides more conformal thin films for the aqueous polymer HIL. When a high-boiling-point solvent and vacuum drying are used for the non-aqueous polymer HTL, however, the film conformity by slot-die coating is higher than that by spin coating. It is attributed that an evaporation-induced convective flow (microflow) occurs from the pixel edge to the center. It also enables the formation of homogeneous light distribution over the emission area of OLED pixels.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Coating was performed by varying the pixel size, solvent, and drying condition. </LI> <LI> Evaporation-induced convective flow occurs from the pixel edge to the center. </LI> <LI> A high-boiling-point solvent and vacuum drying provide high-conformity thin films. </LI> <LI> The emission uniformity of pixels can be enhanced to a great extent. </LI> </UL> </P>

Novel carbazole- and α-carboline derivatives as organic semiconductors for organic thin-film transistors

최동희,김충익 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

Six new carbazole and α-carboline derivatives, 9-(4-(9H-carbazol-9-yl) phenyl)-9H-carbazole , 9-(4-(9H-carbazol-9-yl)phenyl)-9H-pyrido [2,3-b] indole , 9-(3-(9H-carbazol-9-yl)phenyl)-9H-carbazole, 9-(3-(9H-carbazol-9-yl) phenyl)-9H-pyrido [2,3-b] indole, 9-(4-(5-(9H-carbazol-9-yl)thiophen-2-yl) phenyl)-9H-carbazole, and 9-(3-(5-(9H-carbazol-9-yl)thiophen-2-yl) phenyl)-9H-carbazole were synthesized and characterized as organic semiconductors for organic thin-film transistors (OTFTs). Most compounds exhibited p-channel characteristics with relatively low device performance, carrier mobility of 10(-5) - 10(-7)㎠/Vs and a current on/off ratio of 10(4) - 10(6) for top-contact/bottom-gate OTFT devices. The characteristics of devices have been figured out with the film morphologies and mircrostructures with each corressponding compounds. The device characteristics have been correlated with the film morphologies and microstructures of the corresponding compounds.

Solution-Processable Diketopyrrolopyrrole Derivatives as Organic Semiconductors for Organic Thin-Film Transistors

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

Solution-processable diketopyrrolopyrrole derivatives having acetylene, 2,5-bis(2-ethylhexyl)-3-(5(phenylethynyl)thiophen-2-yl)-6-(thiophen- 2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (3), 2,5-bis (2-ethylhexyl) -3-(thiophen-2-yl)-6-(5-(thiophen-2-ylethynyl)thiophen-2-yl)-2,5-dihy dropyrrolo[3,4-c] pyrrole-1,4-dione (4), and 6,6’-((thiophene-2,5-diylbis (ethyne-2,1-diyl))bis(thiophene-5,2-diyl)) bis(2,5-bis(2-ethylhexyl)-3- (thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione) (5) were synthesized and characterized as organic semiconductors for organic thin-film transistors (OTFTs). For the fabrication of thin films based on solution processable compounds, drop-casting (DC) and solutionshearing (SS) were employed. Thin films of compound 5 exhibited p-channel characteristics with carrier mobility as high as 5.7×10^-4 ㎠/Vs and a current on/off ratio of 10⁴-10⁶ for top-contact/bottom-gate OTFT devices.

정량 주입(Pre-metered) 코팅 방식을 이용한 유기 트랜지스터 반도체 박막 제작 연구

조찬연,전홍구,최진성,김윤기,임종선,정준영,조성윤,이창진,박병주,Cho, Chan-Youn,Jeon, Hong-Goo,Choi, Jin-Sung,Kim, Yun-Ki,Lim, Jong-Sun,Jung, J.,Cho, Song-Yun,Lee, Chang-Jin,Park, Byoung-Choo 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.7

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.

Copper phthalocyanine과 Dilithium phthalocyanine 화합물 박막의 휘발성 유기화합물(VOCs) 센서 특성

김동현 ( Dong Hyong Kang ),강영구 ( Young Goo Kang ),강영진 ( Young Jin Kang ) 한국안전학회(구 한국산업안전학회) 2013 한국안전학회지 Vol.28 No.2

In this work, we report the effect on the volatole organic compounds (VOCs) sensing properties of Copper phthalocyanine(CoPc) and Dilithium phthalocyanine (DiLiPc) thin films onto alumina substrates. Use evaporation method and the spin-coated method for sensing device. The materials of metallophthalocyanine macrocyclic compound solutions blended with N,N`-diphenyl-N,N`-bis(1-naphthyl)-1,1`-biphenyl-4,4”-diamine and/or Poly[2-methoxy-5-(2`-ethylhexyloxy)-1,4-phenylenevinylene] solutions. The influence of the blended in with metallophthalocyanine macrocyclic compounds on the resistance have been measured and analyzed in five different volatole organic compounds. The following results were obtained: The AFM 3D image of thin films deposited on metallophthalocyanine macrocyclic compound shows that the surfaces roughness were about CuPc 4.1~14.3 nm(7.5~8.1%), DiLiPc 10.3~22.2 nm(7.9~11.5%). The resistances decreases upon increasing the concentration of vapor organic compounds to CuPc and DiLiPc thin films. That thin films blended Copper phthalocyanine(CoPc) and Dilithium phthalocyanine(DiLiPc) with N,N`-diphenyl-N,N`-bis(1-naphthyl)-1,1`-biphenyl-4,4”-diamine and/or Poly[2-methoxy--5-(2`-ethylhexyloxy)-1,4-phenylenevinylene]. The resistances of blended thin films with N,N`-diphenyl-N,N`-bis(1-naphthyl)-1,1`-biphenyl-4,4”-diamine and/or Poly[2-methoxy--5-(2`-ethylhexyloxy)-1,4-phenylenevinylene] decreases upon increasing the concentration of volatole organic compounds(VOCs) on DiLiPc than CuPc compound thin films.

유기박막트랜지스터 적용을 위한 Soluble Pentacene 박막의 특성연구

공수철,임현승,신익섭,박형호,전형탁,장영철,장호정,Gong, Su-Cheol,Lim, Hun-Seong,Shin, Ik-Sub,Park, Hyung-Ho,Jeon, Hyeong-Tag,Chang, Young-Chul,Chang, Ho-Jung 한국마이크로전자및패키징학회 2007 마이크로전자 및 패키징학회지 Vol.14 No.3

본 연구에서는 유기박막트랜지스터(OTFT, Organic Thin film Transistor)에 응용을 위해 용액(soluble) 공정을 통하여 제작된 pentacene 박막의 특성을 분석하여 pentacene 박막의 OTFT 소자에 적용 가능성을 조사하였다. Pentacene을 용해시키기 위해 toluene과 chloroform의 두 종류의 용제를 사용하였으며, 이들 용제가 pentacene 박막의 특성에 미치는 영향을 연구하였다. Pentacene 용액은 ITO/Glass 기판위에 spin-coating 법으로 유기 반도체 박막을 제작하여 각 박막의 표면형상, 결정화 특성과 전기적 특성을 조사하였다. AFM을 이용한 표면 형상 관찰 결과 chloroform을 이용한 pentacene 박막이 toluene을 이용한 박막에 비하여 표면 거칠기가 개선되는 경향을 보여주었다. XRD 회절 분석 결과 모든 pentacene 박막 시료에서 결정화가 되지 않은 비정질 형태를 보여주었다. Hall effect measurement 분석 결과 chloroform 용제를 이용한 pentacene 박막이 toluene용제를 사용한 시료에 비해 보다 우수한 전기적 특성을 나타내었다. 즉, chloroform에 용해된 pentacene 박막의 경우 전하농도와 이동도는 $-3.225{\times}10^{14}\;cm^{-3}$와 $3.5{\times}10^{-1}\;cm^2\;V^{-1}{\cdot}S^{-1}$를 각각 나타내었다. 또한 비저항은 약 $2.5{\times}10^2\;{\Omega}{\cdot}cm$를 얻었다. In this study, the pentacene thin films were prepared by the soluble process, and characterized fur the application of the organic thin film transistor(OTFT) device. To dissolve the pentacene material, two kinds of solvents such as toluene and chloroform were used, and the effects of these solvents on the properties of pentacene thin films coated on ITO/Glass substrate were investigated. Pentacene thin films were prepared by using spin-coating methode and characterized the surface morphology, crystalline and electrical properties. From the AFM measurement, the surface morphology of the pentacene film dissolved with chloroform was improved compared with the one dissolved with toluene solvent. XRD measurement showed that all prepared pentacene film samples were amorphous crystal phases without crystallization of the films. The electrical properties of the pentacene film dissolved with chloroform showed better results than the ones using toluene solvent by hall measurement system. The carrier concentration and the mobility values of pentacene films using chloroform solvent were found to be $-3.225{\times}10^{14}\;cm^{-3}$ and $3.5{\times}10^{-1}\;cm^2{\cdot}V^{-1}{\cdot}S^[-1}$, respectively. The resistivity was about $2.5{\times}10^2\;{\Omega}{\cdot}cm$.

Solution-Processable, Thin, and High-κ Dielectric Polyurea Gate Insulator with Strong Hydrogen Bonding for Low-Voltage Organic Thin-Film Transistors

Yoo, Sungmi,Kim, Dong-Gyun,Ha, Taewook,Chan Won, Jong,Jang, Kwang-Suk,Kim, Yun Ho American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.38

<P>We developed a solution-processable, thin, and high-dielectric polyurea-based organic gate insulator for low-voltage operation and high performance of organic thin-film transistors (OTFTs). A 60 nm-thick polyurea thin film exhibited a high dielectric constant of 5.82 and excellent electrical insulating properties owing to strong hydrogen bonding. The hydrogen bonding of the synthesized polyurea was confirmed using infrared spectroscopy and was quantitatively evaluated by measuring the interactive force using atomic force microscopy. Moreover, the effect of hydrogen bonding of polyurea on the insulating properties was systematically investigated through the combination of various monomers and control of the thickness of the polyurea film. The dinaphtho[2,3-<I>b</I>:2′,3′-<I>f</I>]thieno[3,2-<I>b</I>]thiophene-based OTFTs with the polyurea gate insulator showed excellent thin-film transistor (TFT) performance with a field-effect mobility of 1.390 cm<SUP>2</SUP>/V·s and an on/off ratio of ∼10<SUP>5</SUP> at a low operation voltage below 2 V. In addition, it is possible to fabricate flexible polymer organic semiconductor (OSC)-based TFT devices using a solution process, owing to excellent solvent stability in various organic solvents. We believe that the solution-processable polyurea gate insulator with a high dielectric constant and good insulation properties is a promising candidate for low-voltage-operated OTFTs using various OSCs.</P> [FIG OMISSION]</BR>

후열처리된 펜타센 유기박막 트랜지스터

이연섭,전성훈,Shant ARAKELYAN,정영훈,장현욱,한혜지,김용재,이한주,이기진,차덕준 한국물리학회 2016 New Physics: Sae Mulli Vol.66 No.2

In this research, we treated the pentacene OTFTs (organic thin film transistors) with post-annealing process after deposition. The thicknesses of the pentacene thin films and the post-annealing temperatures were 15 nm, 70 nm, 200 nm and RT (room temperature), 70 $^\circ$C, 100 $^\circ$C, 130 $^\circ$C, 160 $^\circ$C, respectively. The crystalline structures of the pentacene organic thin films were observed by using X-ray diffraction and atomic force microscopy. For pentacene OTFTs, we found that the traps at the pentacene thin films coexist with the bulk and that the thin-films phases prevent any improvement of the electrical properties. The mobility of the pentacene OTFT with a film thickness of 15 nm was recorded as the highest one, and the mobility of the pentancene OTFT treated at a post-annealing temperature of 70 $^\circ$C was recorded as 0.0151 cm$^{2}$/V$\cdot$s, which was the highest value for the post-annealing process. 본 논문에서는 펜타센 유기물을 고진공 상태에서 열증착 한 후 후열처리에 의한 유기물 박막의 변화를 관측하였다. SiO$_{2}$ 절연체가 200 nm 코팅된 실리콘 기판에 펜타센 박막을 0.2 $\sim$ 4 \AA$\cdot$s$^{-1}$의 속도로 15 nm, 70 nm, 200 nm 만큼씩 쌓았다. 후열처리 온도는 RT, 70 $^\circ$C, 100 $^\circ$C, 130 $^\circ$C, 160 $^\circ$C로 주었다. 펜타센 박막을 이용해서 X선 회절 (X-ray diffraction, XRD), 원자현미경 (atomic force microscopy, AFM)를 사용해 유기물 박막의 표면과 구조가 후열처리에 따라 변하는 것을 확인하였다. 유기물 박막 위에 금으로 소스 및 드레인 층을 증착하여, 펜타센 박막의 후열처리 조건에 따른 펜타센 OTFTs의 전기적 특성 변화를 관측하였다. 덩어리 상태 (bulk phase)와 박막 상태 (thin film phase)의 공존에 의해 생긴 트랩은 후열처리를 하더라도 개선하기 어렵다는 것을 확인하였다. 전하이동도만을 고려하면 두께는 15 nm에서 좋은 전하이동도를 보였고, 70 $^\circ$C로 후열처리 했을 때, 0.0151 cm$^{2}$/V$\cdot$s 로 후열처리 조건 중에서 가장 높은 전하이동도를 보였다.