Air-Processable Silane-Coupled Polymers to Modify a Dielectric for Solution-Processed Organic Semiconductors

Jang, Mi; Yu, Young Chang; Jeon, Hyeonyeol; Youk, Ji Ho; Yang, Hoichang

doi:10.1021/am508573q

Cited by 6 publications

(3 citation statements)

References 37 publications

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“…Materials and Sample Preparation : Styrene (St, Aldrich, ≥99%) was passed through neutral alumina, dried over calcium hydride, distilled under reduced pressure, and degassed using three freeze–pump–thaw cycles . This purification process was also performed for 1,4‐dioxane (Duksan, 99%), methyl ethyl ketone (MEK or 2‐butanone, Duksan, 99%), 2,3,4,5,6‐pentafluorostyrene (PFS, Aldrich, 99%), and 2,2′‐azobisisobutyronitrile (AIBN, Junsei, 96%): AIBN was used after being recrystallized twice in methanol.…”

Section: Methodsmentioning

confidence: 99%

Balancing Surface Hydrophobicity and Polarizability of Fluorinated Dielectrics for Organic Field‐Effect Transistors with Excellent Gate‐Bias Stability and Mobility

Jang

Lee

Shin

et al. 2016

Adv Materials Inter

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It is demonstrated that treating dielectrics with fluorinated polymers, which have excellent hydrophobicity, chemical inertness, and the lowest polarizability, yields a semiconductor‐compatible surface energy and excellent charge detrapping characteristics. Fluorocopolymers, polystyrene‐random‐poly(2,3,4,5,6‐pentafluorostyrene) (PS‐r‐PPFS) copolymers with different 2,3,4,5,6‐pentafluorostyrene (PFS) loadings, are synthesized to modify a SiO2 gate dielectric using radical polymerization. Surface energy (γ) of the copolymer‐treated SiO2 dielectrics decreases from 40.7 to 24.0 mJ m−2 with increasing PFS mol% in the copolymer. Pentacene organic field‐effect transistors (OFETs) show field‐effect mobility (μFET) values ranging from 0.82 (for 0 mol% PFS) to 0.25 cm2 V−1 s−1 (for 100 mol% PFS). Enhancing the bias stress stability without affecting the μFET value is achieved via the introduction of a small mol% fluorocarbon segments onto the PS‐r‐PPFS backbone. 15 mol% PFS‐loaded fluorocopolymer‐coated SiO2 substrate yields a γ value of 35 mJ m−2, close to that (38 mJ m−2) of the lowest‐γ crystal surface of pentacene, and the corresponding OFETs have μFET values up to 0.81 cm2 V−1 s−1 and excellent gate‐bias stress stability in comparison to the rich fluorinated dielectric systems, which has degraded μFET values ranging from 0.2 to 0.4 cm2 V−1 s−1.

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Section: Methodsmentioning

confidence: 99%

Balancing Surface Hydrophobicity and Polarizability of Fluorinated Dielectrics for Organic Field‐Effect Transistors with Excellent Gate‐Bias Stability and Mobility

Jang

Lee

Shin

et al. 2016

Adv Materials Inter

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“…Another concept uses polymers with related functional side chains containing cross-linkable moieties which can uniquely react with each other under a thermal or UV treatment. [20][21][22][23][24] No separate cross-linking unit is necessary. Examples thereof are polyacrylates functionalized by hydroxyl and epoxy groups.…”

Section: Introductionmentioning

confidence: 99%

Cross-linkable random copolymers as dielectrics for low-voltage organic field-effect transistors

et al. 2015

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A large number of cross-linkable dielectrics with good dielectric properties have been reported; however, all of them suffer from disadvantages like uncontrolled pre-crosslinking, necessity of high process temperatures and the need for an additional cross-linking compound. In this contribution, two new poly(methyl methacrylate) polymers are introduced which can be cross-linked due to the attached benzyl azide (N3) monomer units making the addition of hardeners or initiators obsolete. The synthesis of the copolymers as well as their successful characterization and usage as gate dielectrics for organic field-effect transistors is demonstrated. The investigated polymers have been labeled PAZ 12 and PAZ 14 according to their azide content in mol%. The additional building blocks of the polymers are methyl methacrylate for PAZ 12 and methyl methacrylate and styrene monomer units in about an equal ratio for PAZ 14. Spin-coated thin films were cross-linked by a thermal treatment at 110 °C followed by an UV exposure at a wavelength of 254 nm yielding insoluble, smooth and electrically dense polymeric networks. Optimal cross-linking parameters were obtained using infrared spectroscopy to follow the N3 vibrational mode. Its disappearance confirms a complete cross-linking reaction, and thus fully reacted azide groups facilitate the analytics. The dielectric properties of the cross-linked thin films have been studied by impedance spectroscopy. The application of double layer dielectrics results in lower dielectric losses and lower leakage currents in the subsequently produced pentacene-based field-effect transistors. These devices operate at voltages below −6 V and show hysteresis-free current–voltage characteristics with hole mobilities up to 0.16 cm2 V−1 s−1. PAZ 12 appears to be superior to PAZ 14 due to a lower total layer thickness of down to 92 nm still providing good insulation in the transistor presumably related to a lower free volume that arises in the cross-linked network of the two-component containing copolymer PAZ 12

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“…10 The roughness, surface energy and trap density of the dielectric lm have directly inuenced the morphology of the active layer and then further determined the transport of the charge carrier. [11][12][13] In addition, an uneven dielectric location over a large area results in a wide distribution of the device performances, which is a handicap in the fabrication of qualied organic circuits. 14 At present, there are three kinds of dielectric in organic electronics: inorganic insulators, self-assembled monolayer (SAM) dielectrics and polymer dielectrics.…”

Section: Introductionmentioning

confidence: 99%

Polyimide (PI) high-quality polymer dielectric films with the features of anti-solvents and large-area consistency for field-effect transistors

Dong

et al. 2015

RSC Adv.

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In this work, the properties of polyimide (PI) as the dielectric film are systematically investigated. PI films are processed by spin-coating method at various conditions. Subsequently, the leakage current, unit-area capacitance and morphologies of these films are characterized. Then anti-solvent property is certified by comparing the films before and after the solvent treatments. Organic filed-effect transistors based on PI dielectric films and pentacene active films show uniform performance distribution in large area. Furthermore, a single crystal of 2,7-dihexyl-dibenzo[d, d′]thieno[3,2-b;4,5-b′]dithiophene (C6-DBTDT)is obtained on the PI film by solution-processed method and exhibits good electrical properties with the highest mobility of 3 cm 2 V -1 s -1 and I on /I off > 10 5 . It is believed that this kind of PI polymer dielectric film has potential application in solution-processed, flexible and large-area organic electronics.. Therefore, it is necessary to introduce a new polymer dielectric that can endure this oppressive preparation process.Polyimide (PI) is a good candidate of polymer dielectric film 24-26 and in our work, we do systematical research on this polymeric insulator. The leakage current, unit-area capacitance and the morphologies of these films are characterized. Then anti-solvent property is certified by comparing these films before and after organic solvent treatment. Large-area thin film OFET arrays show uniform mobility and threshold voltage distribution. Furthermore, solution-processed single crystal OFETsare built on the PI films. Bottom-gate top-contact OFETs are constructed by manually gluing Au-films, which exhibit excellent electrical properties with the highest mobility up to 3 cm 2 V -1 s -1 and I on /I off > 10 5 . It is believed that this kind of polymer insulator has potential application in solution-processed organic electronics. Experimental sectionIn this work, PI films were prepared by spin-coating onto indium tin oxide (ITO) substrates and all substrates were cleaned with deionized water, acetone, and isopropyl alcohol in ultrasound for 10 minutes respectively, and then dried with quickly purged N 2 . The substrates were further cleaned in oxygen plasma for 5 minutes. PI precursor (polyimide acid, PAA) films were firstly spin-coated on ITO substrates at different speed (2000 rpm, 4000 rpm, 6000 rpm and 8000rpm) for 30 seconds. Then, these films were cross-linked to form solid PI films with annealing temperature of 300 o C. After that, the morphologies and thicknesses of these films were investigated by atomic force microscope (AFM) with tapping mode.In order to measure the leakage current and unit-area capacitance of PI films, the devices with ITO/PI/Au (100 nm) sandwich structure were fabricated. The specific capacitance as a function of frequency based on PI film was tested by electrochemical method. The leakage current of PI was characterized by Keithley 4200-SCS semiconductor analyzer. Bottom-gate top-contact OFETs were fabricated employing PI as dielectric film, p...

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Air-Processable Silane-Coupled Polymers to Modify a Dielectric for Solution-Processed Organic Semiconductors

Cited by 6 publications

References 37 publications

Balancing Surface Hydrophobicity and Polarizability of Fluorinated Dielectrics for Organic Field‐Effect Transistors with Excellent Gate‐Bias Stability and Mobility

Balancing Surface Hydrophobicity and Polarizability of Fluorinated Dielectrics for Organic Field‐Effect Transistors with Excellent Gate‐Bias Stability and Mobility

Cross-linkable random copolymers as dielectrics for low-voltage organic field-effect transistors

Polyimide (PI) high-quality polymer dielectric films with the features of anti-solvents and large-area consistency for field-effect transistors

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