Browsing by Author "Chen, Ming-Chou"

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High performance solution-processable tetrathienoacene (TTAR) based small molecules for organic field effect transistors (OFETs)
(2017-05-28)
Vegiraju, Sureshraju
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Huang, Deng-Yi
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Priyanka, Pragya
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Li, Yo-Shan
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Luo, Xian-Lun
Three new organic semiconductors with alkyl chain-substituted tetrathienoacene (TTAR) as the central core and both ends capped with thiophene (DT-TTAR), thienothiophene (DTT-TTAR) and dithienothiophene (DDTT-TTAR) have been synthesized and characterized for organic field effect transistor (OFET) applications. A hole mobility of 0.81 cm(2) V-1 s(-1) was achieved for the DDTT-TTAR film, which represents the highest mobility yet found for a solution-processable p-type TTAR-based small molecular semiconductors.
Influence of polymer dielectric surface energy on thin-film transistor performance of solution-processed triethylsilylethynyl anthradithiophene (TES-ADT)
(2012-02-01)
Chen, Liang-Hsiang
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Lin, Pang
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Kim, Choongik
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Chen, Ming-Chou
;
Huang, Peng-Yi
This study investigates the correlation between surface energy of polymer dielectrics and the film morphology, microstructure, and thin-film transistor performance of solution-processed 5,11-bis(triethylsilylethynyl) anthradithiophene (TES-ADT) films. The low surface energy polyimide (PI) dielectric induced large grains with strong X-ray reflections for spin-cast TES-ADT films in comparison to high surface energy poly(4-vinyl phenol) (PVP) dielectric. Furthermore, thin-film transistors based on spin-cast TES-ADT films on PI dielectric exhibited enhanced electrical performance, small hysteresis, and high stability under bias stress with carrier mobility as high as 0.43 cm(2)/Vs and a current on/off ratio of 10(7). (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Intramolecular Locked Dithioalkylbithiophene-Based Semiconductors for High-Performance Organic Field-Effect Transistors
(2017-09-20)
Vegiraju, Sureshraju
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Chang, Bo-Chin
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Priyanka, Pragya
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Huang, Deng-Yi
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Wu, Kuan-Yi
New 3,3-dithioalkyl-2,2-bithiophene (SBT)-based small molecular and polymeric semiconductors are synthesized by end-capping or copolymerization with dithienothiophen-2-yl units. Single-crystal, molecular orbital computations, and optical/electrochemical data indicate that the SBT core is completely planar, likely via S(alkyl)S(thiophene) intramolecular locks. Therefore, compared to semiconductors based on the conventional 3,3-dialkyl-2,2-bithiophene, the resulting SBT systems are planar (torsional angle <1 degrees) and highly -conjugated. Charge transport is investigated for solution-sheared films in field-effect transistors demonstrating that SBT can enable good semiconducting materials with hole mobilities ranging from approximate to 0.03 to 1.7 cm(2) V-1 s(-1). Transport difference within this family is rationalized by film morphology, as accessed by grazing incidence X-ray diffraction experiments.
Polyimide/Ta(2)O(5) nanocomposite gate insulators for enhanced organic thin-film transistor performance
(2011-08-01)
Chen, Liang-Hsiang
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Lin, Pang
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Ho, Jia-Chong
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Lee, Cheng-Chung
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Kim, Choongik
This study reports the preparation and characterization of polyimide/Ta(2)O(5) nanocomposite films as insulators for organic thin-film transistors (OTFTs). The degree of imidization, thermal, electrical, and surface properties of the nanocomposite films were characterized as a function of Ta(2)O(5) precursor contents. The nanocomposite films, with controlled/comparable insulator electrical characteristics and surface properties, have been found to enhance dielectric constant compared to pristine polyimide films, which resulted in improved pentacene TFT performance by a factor of 2-3 with carrier mobility values as high as 0.38 cm(2)/Vs. (C) 2011 Elsevier B.V. All rights reserved.
Polyimide/Ta2O5 nanocomposite gate insulators for enhanced organic thin-film transistor performance
(2011-08-01)
Chen, Liang-Hsiang
;
Lin, Pang
;
Ho, Jia-Chong
;
Lee, Cheng-Chung
;
Kim, Choongik
This study reports the preparation and characterization of polyimide/Ta2O5 nanocomposite films as insulators for organic thin-film transistors (OTFTs). The degree of imidization, thermal, electrical, and surface properties of the nanocomposite films were characterized as a function of Ta2O5 precursor contents. The nanocomposite films, with controlled/comparable insulator electrical characteristics and surface properties, have been found to enhance dielectric constant compared to pristine polyimide films, which resulted in improved pentacene TFT performance by a factor of 2-3 with carrier mobility values as high as 0.38 cm(2)/Vs. (C) 2011 Elsevier B.V. All rights reserved.
Silver nanowire-polymer composite electrode for high performance solution-processed thin-film transistors
(2012-10-01)
Chen, Liang-Hsiang
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Lin, Pang
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Chen, Ming-Chou
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Huang, Peng-Yi
;
Kim, Choongik
Silver nanowires (AgNWs)/poly-(3,4-ethylenedioxythiophene/polystyrene sulphonate) (PEDOT:PSS) composite films as conductive electrode for OTFTs were prepared, and their optical and electrical properties were investigated. The conductive composite films used in this study afforded low sheet resistance of <140 Omega/sq and transmittance as high as 70% in the visible region. For the composite film with 0.1 wt.% of AgNWs, contact resistance as low as 2.7 x 10(4) Omega cm was obtained, as examined by Transfer length model (TLM) analysis, and work function of the corresponding film was 5.0 eV. Furthermore, the composite films were employed as source and drain electrodes for top-gate/bottom-contact organic thin-film transistors (OTFTs) based on solution-processed 5,11-bistriethylsilylethynyl anthradithiophene (TES-ADT) as organic semiconductor, and the resulting device showed high electrical performance with carrier mobility as high as 0.21 cm(2)/V s. (C) 2012 Elsevier B.V. All rights reserved.
Solution-Processable Quinoidal Dithioalkylterthiophene-Based Small Molecules Pseudo-Pentathienoacenes via an Intramolecular S center dot center dot center dot S Lock for High-Performance n-Type Organic Field-Effect Transistors
(2020-06-03)
Vegiraju, Sureshraju
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Torimtubun, Alfonsina Abat Amelenan
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Lin, Po-Shen
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Tsai, Hsin-Chia
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Lien, Wei-Chieh
A new organic small-molecule family comprising tetracyanoquinodimethane-substituted quinoidal dithioalky(SR)terthiophenes (DSTQs) (DSTQ-6 (1); SR = SC6H13, DSTQ : 10 (2); SR = SC10H21, DSTQ14 (3); SR = SC10H21) was synthesized and contrasted with a nonthioalkylated analogue (DRTQ14 (4); R = C14H29). The physical, electrochemical, and electrical properties of these new compounds are thoroughly investigated. Optimized geometries obtained from density functional theory calculations and single-crystal X-ray diffraction reveal the planarity of the SR-containing DSTQ core. DSTQs pack in a slipped pi-pi stacked two-dimensional arrangement, with a short intermolecular stacking distance of 3.55 A and short intermolecular S center dot center dot center dot N contacts of 3.56 angstrom. Thin-film morphological analysis by grazing incident X-ray diffraction reveals that all DSTQ molecules are packed in an edge-on fashion on the substrate. The favorable molecular packing, the high core planarity, and very low lowest unoccupied molecular orbital (LUMO) energy level (-4.2 eV) suggest that DSTQs could be electron-transporting semiconductors. Organic field-effect transistors based on solution-sheared DSTQ : 14 exhibit the highest electron mobility of 0.77 cm(2) V-1 s(-1) with good ambient stability, which is the highest value reported to date for such a solution process terthiophene-based small molecular semiconductor. These results demonstrate that the device performance of solution-sheared DSTQs can be improved by side chain engineering.
Solution-Processed High-Performance Tetrathienothiophene-Based Small Molecular Blends for Ambipolar Charge Transport
(2018-07-11)
Vegiraju, Sureshraju
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Lin, Chih-Yu
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Priyanka, Pragya
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Huang, Deng-Yi
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Luo, Xian-Lun
Four soluble dialkylated tetrathienoacene (TTAR)-based small molecular semiconductors featuring the combination of a TTAR central core, pi-conjugated spacers comprising bithiophene (bT) or thiophene (T), and with/without cyanoacrylate (CA) end-capping moieties are synthesized and characterized. The molecule DbT-TTAR exhibits a promising hole mobility up to 0.36 cm(2) V-1 s(-1) due to the enhanced crystallinity of the microribbon-like films. Binary blends of the p-type DbT-TTAR and the n-type dicyanomethylene substituted dithienothiophene-quinoid (DTTQ-11) are investigated in terms of film morphology, microstructure, and organic field-effect transistor (OFET) performance. The data indicate that as the DbT-TTAR content in the blend film increases, the charge transport characteristics vary from unipolar (electron-only) to ambipolar and then back to unipolar (hole-only). With a 1:1 weight ratio of DbT-TTAR DTTQ-11 in the blend, well-defined pathways for both charge carriers are achieved and resulted in ambipolar transport with high hole and electron mobilities of 0.83 and 0.37 cm(2) V-1 s(-1), respectively. This study provides a viable way for tuning microstructure and charge carrier transport in small molecules and their blends to achieve high-performance solution-processable OFETs.
Solution-Processed Small-Molecule Bulk Heterojunction Ambipolar Transistors
(2014-04-01)
Cheng, Shiau-Shin
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Huang, Peng-Yi
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Ramesh, Mohan
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Chang, Hsiu-Chieh
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Chen, Li-Ming
Solution-processed small-molecule bulk heterojunction (BHJ) ambipolar organic thin-film transistors are fabricated based on a combination of [2-phenylbenzo[d,d \']thieno[3,2-b;4,5-b \']dithiophene (P-BTDT) : 2-(4-n-octylphenyl)benzo[d,(d) under bar \']thieno[3,2-b;4,5-b\']dithiophene (OP-BTDT)] and C-60. Treating high electrical performance vacuum-deposited P-BTDT organic semiconductors with a newly developed solution-processed organic semiconductor material, OP-BTDT, in an optimized ratio yields a solution-processed p-channel organic semiconductor blend with carrier mobility as high as 0.65 cm(2) V-1 s(-1). An optimized blending of P-BTDT:OP-BTDT with the n-channel semiconductor, C-60, results in a BHJ ambipolar transistor with balanced carrier mobilities for holes and electrons of 0.03 and 0.02 cm(2) V-1 s(-1), respectively. Furthermore, a complementary-like inverter composed of two ambipolar thin-film transistors is demonstrated, which achieves a gain of 115.