Thermal Molding of Organic Thin-Film Transistor Arrays on Curved Surfaces
© The Author(s) 2017
Received: 31 January 2017
Accepted: 26 April 2017
Published: 12 May 2017
In this work, a thermal molding technique is proposed for the fabrication of plastic electronics on curved surfaces, enabling the preparation of plastic films with freely designed shapes. The induced strain distribution observed in poly(ethylene naphthalate) films when planar sheets were deformed into hemispherical surfaces clearly indicated that natural thermal contraction played an important role in the formation of the curved surface. A fingertip-shaped organic thin-film transistor array molded from a real human finger was fabricated, and slight deformation induced by touching an object was detected from the drain current response. This type of device will lead to the development of robot fingers equipped with a sensitive tactile sense for precision work such as palpation or surgery.
Plastic and printed electronics have recently attracted extensive interest for flexible and stretchable device applications. However, research on device fabrication technologies for curved surfaces is not as active even though many modern commodities consist of smoothly curved plastics such as poly(ethylene terephthalate) bottles, blister packs, medical tubes, and connectors. Although the adaptability of stretchable electronics to spherical surfaces has been demonstrated , stretchable devices generally cannot maintain their self-standing shape on their own. Therefore, not only flexible or stretchable devices but also curved-surface devices are needed for a wide range of applications. For example, if robot fingertips could be equipped with sensitive thermal and tactile sense using curved-surface electronic devices, more precise surgical operation could be performed using medical robots.
In this paper, we present a novel technique to fabricate an electronic device array on a freely designed curved surface via thermal molding of plastic sheets and direct melting of organic semiconductors with subsequent recrystallization, which is expected to enable the preparation of 3D plastic electronics. We fabricated a fingertip-shaped organic thin-film transistor (OTFT) array as a curved surface device test case and succeeded in detecting slight deformation induced by a soft touch from an object.
Results and Discussion
The carrier mobility and threshold voltage map presented in Fig. 4 b, c summarizes the properties of the 88 TFTs. The working OTFTs are colored along the effective field-effect mobility. A group of working OTFTs are observed. However, the thicknesses of the OTFTs were not sufficiently uniform because of the limitation in mechanical precision of the present mold. Therefore, the distributions of the observed field-effect hole mobility and threshold voltage were wide at present.
The fabrication of plastic electronics on curved surfaces using thermal molding was demonstrated in this work. The induced strain distribution of PEN films when planar sheets were deformed into spherical surfaces clearly indicated that natural thermal contraction played an important role in the formation of the curved surface to avoid excess tensile strain, which could result in fracture of the electrode pattern. The OTFT characteristics of a fingertip-shaped OTFT array molded from a real human finger were also examined. The drain current response to slight deformation induced by touching an object clearly increased with increasing internal strain. By scanning the OTFTs, it would be possible to detect the hardness or edge of an object based on the internal strain distribution. This type of device array fabricated on a curved surface will enable the development of robot fingers equipped with a sensitive tactile sense, which is sufficient for precision work such as palpation or surgery.
The authors acknowledge Jun-rou Hayashi and Yushi Sasaki for their experimental help. The authors would like to thank Nippon Pneumatic Mfg. Co., Ltd., Japan for providing the pulverized organic semiconductor material prepared by supersonic jet milling. The authors would also like to thank Teijin Ltd., Japan, for providing the PEN films. This work was financially supported by a research grant from the CASIO Science Promotion Foundation.
This work was financially supported by a research grant from the CASIO Science Promotion Foundation.
MS is the corresponding author and principal investigator of this research work. KW and HI are graduate school students who carried out the experiments. YO and HY are lab members and provided the experimental and technical help. YS provided the organic semiconductor material. KK is the professor and director of this lab and provided a useful advice. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
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- Ko HC, Stoykovich MP, Song J, Malyarchuk V, Choi WM, Yu CJ, et al. (2008) A hemispherical electronic eye camera based on compressible silicon optoelectronics. Nature454: 748.View ArticleGoogle Scholar
- Kitamura M, Arakawa Y (2011) High Current-Gain Cutoff Frequencies above 10 MHz in n-Channel C60 and p-Channel Pentacene Thin-Film Transistors. Jpn J Appl Phys50: 01BC01.View ArticleGoogle Scholar
- Kitamura M, Kuzumoto Y, Aomori S, Arakawa Y (2011) High-frequency Organic Complementary Ring Oscillator Operating up to 200 kHz. Appl Phys Express4: 051601.View ArticleGoogle Scholar
- Kitamura M, Kuzumoto Y, Kang W, Aomori S, Arakawa Y (2010) High conductance bottom-contact pentacene thin-film transistors with gold-nickel adhesion layers. Appl Phys Lett97: 033306.View ArticleGoogle Scholar
- Kuzumoto Y, Kitamura M (2014) Work function of gold surfaces modified using substituted benzenethiols: Reaction time dependence and thermal stability. Appl Phys Express7: 035701.View ArticleGoogle Scholar
- Kitamura M, Kuzumoto Y, Arakawa Y (2013) Short-Channel, high-mobility organic thin-film transistors with alkylated dinaphthothienothiophene. Physica Status Solidi C10: 1632–5.View ArticleGoogle Scholar
- Ebata H, Izawa T, Miyazaki E, Takimiya K, Ikeda M, Kuwabara H, et al. (2007) Highly Soluble Benzothieno[3,2-b]benzothiophene (BTBT) Derivatives for High-Performance, Solution-Processed Organic Field-Effect Transistors. J Am Chem Soc129: 15732.View ArticleGoogle Scholar
- Uemura T, Hirose Y, Uno M, Takimiya K, Takeya J (2009) Very High Mobility in Solution-Processed Organic Thin-Film Transistors of Highly Ordered Benzothieno[3,2-b]benzothiophene Derivatives. Appl Phys Express2: 111501.View ArticleGoogle Scholar
- Endo T, Nagase T, Kobayashi T, Takimiya K, Ikeda M, Naito H (2010) Solution-Processed Dioctylbenzothienobenzothiophene-Based Top-Gate Organic Transistors with High Mobility, Low Threshold Voltage, and High Electrical Stability. Appl Phys Express3: 121601.View ArticleGoogle Scholar
- Kano M, Minari T, Tsukagoshi K (2010) All-Solution-Processed Selective Assembly of Flexible Organic Field-Effect Transistors Arrays. Appl Phys Express3: 051601.View ArticleGoogle Scholar
- Takimiya K, Shinamura S, Osaka I, Miyazaki E (2011) Thienoacene -Based Organic Semiconductors. Adv Mater23: 4347.View ArticleGoogle Scholar
- Liu C, Minari T, Lu X, Kumatani A, Takimiya K, Tsukagoshi K (2011) Solution-Processable Organic Single Crystals with Bandlike Transport in Field-Effect Transistors. Adv Mater23: 523.View ArticleGoogle Scholar
- Minemawari H, Yamada T, Matsui H, Tsutsumi J, Haas S, Chiba R, et al (2011) Inkjet printing of single-crystal films. Nature475: 364.View ArticleGoogle Scholar
- Soeda J, Hirose Y, Yamagishi M, Nakao A, Uemura T, Nakayama K, et al. (2011) Solution-Crystallized Organic Field-Effect Transistors with Charge-Acceptor Layers: High-Mobility and Low-Threshold-Voltage Operation in Air. Adv Mater23: 3309.View ArticleGoogle Scholar
- Tanaka H, Kozuka M, Watanabe S, Ito H, Shimoi Y, Takimiya K, et al. (2011) Observation of field-induced charge carriers in high-mobility organic transistors of a thienothiophene-based small molecule: Electron spin resonance measurements. Phys Rev B84: 081306(R).View ArticleGoogle Scholar
- Li Y, Liu C, Kumatani A, Darmawan P, Minari T, Tsukagoshi K (2011) Patterning solution-processed organic single-crystal transistors with high device performance. AIP Advances1: 022149.View ArticleGoogle Scholar
- Minari T, Liu C, Kano M, Tsukagoshi K (2012) Controlled Self-Assembly of Organic Semiconductors for Solution-Based Fabrication of Organic Field-Effect Transistors. Adv Mater24: 299.View ArticleGoogle Scholar
- Minari T, Darmawan P, Liu C, Li Y, Xu Y, Tsukagoshi K (2012) Highly enhanced charge injection in thienoacene-based organic field-effect transistors with chemically doped contact. Appl Phys Lett100: 093303.View ArticleGoogle Scholar
- Kumatani A, Liu C, Li Y, Darmawan P, Takimiya K, Minari T, et al. (2012) Solution-processed, Self-organized Organic Single Crystal Arrays with Controlled Crystal Orientation. Scientific Reports2: 393.View ArticleGoogle Scholar
- Li Y, Liu C, Xu Y, Minari T, Darmawan P, Tsukagoshi K (2012) Solution-processed organic crystals for field-effect transistor arrays with smooth semiconductor/dielectric interface on paper substrates. Organic Electronics13: 815.View ArticleGoogle Scholar
- Li Y, Liu C, Kumatani A, Darmawan P, Minari T, Tsukagoshi K (2012) Large plate-like organic crystals from direct spin-coating for solution-processed field-effect transistor arrays with high uniformity. Organic Electronics13: 264.View ArticleGoogle Scholar
- Li Y, Liu C, Lee MV, Xu Y, Wang X, Shi Y, et al. (2013) In situ purification to eliminate the influence of impurities in solution-processed organic crystals for transistor arrays. J Mater Chem C1: 1352.View ArticleGoogle Scholar
- Inoue A, Okamoto T, Sakai M, Kuniyoshi S, Yamauchi H, Nakamura M, Kudo K (2013) Flexible organic field-effect transistor fabricated by thermal press process. Phys Status Solidi A210: 1353.View ArticleGoogle Scholar
- Sakai M, Okamoto T, Yamazaki Y, Hayashi J, Yamaguchi S, Kuniyoshi S, et al. (2013) Organic thin-film transistor fabricated between flexible films by thermal lamination. Physica Status Solidi7: 1093.View ArticleGoogle Scholar
- Ishii H, Kudo K, Nakayama T, Ueno N (2015) Electronic processes in organic electronics, Springer Series in Materials Science, vol 209; chapter 9 In: Bridging Nanostructure, Electronic States and Device Properties.Google Scholar
- Sasaki T, Sakai M, Ko T, Okada Y, Yamauchi H, Kudo K, et al. (2016) Solvent-free Printing of the Flexible Organic Thin Film Transistors by Ultrasonic Welding Method. Adv Electron Mater2: 1500221.View ArticleGoogle Scholar
- Sekitani T, Iba S, Kato Y, Noguchi Y, Someya T, Sakurai T (2005) Ultraflexible organic field-effect transistors embedded at a neutral strain position. Appl Phys Lett87: 173502.View ArticleGoogle Scholar
- Sakai M, Yamazaki Y, Yamaguchi S, Hayashi J, Kudo K (2014) Mechanical analysis of organic flexible devices by finite element calculation. Phys Status Solidi A211: 795.View ArticleGoogle Scholar
- Suo Z, Ma EY, Gleskova H, Wagner S (1999) Mechanics of rollable and foldable film-on-foil electronics. Appl Phys Lett74: 1177.View ArticleGoogle Scholar
- Kanari M, Kunimoto M, Wakamatsu T, Ihara I (2010) Critical bending radius and electrical behaviors of organic field effect transistors under elastoplastic bending strain. Thin Solid Films518: 2764.View ArticleGoogle Scholar
- Kim N, Graham S (2013) Development of highly flexible and ultra-low permeation rate thin-film barrier structure for organic electronics. Thin Solid Films547: 57.View ArticleGoogle Scholar