| 研究課題/領域番号 |
15K21617
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| 研究機関 | 国立研究開発法人物質・材料研究機構 |
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研究代表者 |
リュウ シューイン 国立研究開発法人物質・材料研究機構, 国際ナノアーキテクトニクス研究拠点, NIMSポスドク研究員 (30751317)
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| 研究期間 (年度) |
2015-04-01 – 2017-03-31
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| キーワード | printed electronics / thin-film transistors |
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| 研究実績の概要 |
Through fully printing techniques, we fabricated organic thin-film transistors with high performance. Firstly, we printed electrodes using a gold nanoparticle ink, which yielded very uniform electrode surface and thus is beneficial to the achievement of good interfacial states. And then, a removable substrate was used and allowed the deposition of discrete organic semiconducting thin films with rather thin thickness less than 50 nm, which also had a smooth surface. After depositing dielectric layer and top gate, we achieved fully printed organic thin-film transistors at room temperature.
The obtained transistors exhibited high mobility and on/off ratio of 9.2 cm2V-1s-1 and 10 to 9th power, respectively. Furthermore, we developed a solution process for p-dopants that aqueous transition metal oxide solutions can be precisely deposited onto the bottom electrodes to modify the interface state, which significantly enhanced the devices' characteristics, resulting in the higher mobility of 13 cm2V-1s-1 with the contact resistance decreasing to 3.8 kohm cm and lower threshold voltage. The current procedure actually makes the fully solution-processed separate TFTs and doping of electrodes possible, which will be promising for high-resolution AM-LCDs.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
1. New gold nanoparticle inks. We printed electrodes using a new Au nanoparticle ink with a nice patterning property, therefore can print very uniform electrode with a smooth surface, which helped us realize good interfacial states.
2. Removable guide layers for depositing organic semiconducting thin films.A removable substrate was developed and allowed the deposition of discrete organic semiconducting thin films with rather thin thickness less than 50 nm, which also had smooth surface. The thin organic semiconductor film has well-aligned crystal domains covering the channel regions in OTFT devices.
3. Precisely controlling the thickness of dielectric layers.The thickness of dielectric layers can be quantitatively controlled by the weight of dielectric materials in CVD process. Therefore, we could prepare a properly thick dielectric layer for OTFT device. After depositing dielectric layer and top gate, we achieved fully printed organic thin-film transistors at room temperature.
4. A new method was developed for depositing dopants.We developed a solution process for p-dopants that aqueous transition metal oxide solutions can be precisely deposited onto the bottom electrodes to modify the interface state, which significantly enhanced the devices’ characteristics, resulting in the higher mobility.
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| 今後の研究の推進方策 |
1. Improvement of devices' performance.The aim of this research is to achieve high average mobility up to 10 cm2V-1s-1. Taking account of the requirement of practical conditions, the fabricated devices must be further improved. Firstly, thermal-tolerance can be ensured because of their stability over 200 ℃.and then, the charge carrier mobility can be enhanced by improving the molecular orientation of active layer, and also can be increased by decreasing contact resistance through incorporation of a doping layer between source/drain electrodes and active layer. Low threshold voltage around 0 V will be achieved by inserting an insulating layer (like CYTOP) into gate electrode and the active layer.
2. Construction of devices toward integration on flexible substrates through fully-printing techniques.This work will be done in Minari group (Fully-printed electronics laboratory) in NIMS. The preparation of polymer substrates with gold electrodes by printing has already been reported in our previous publication (Minari et al., Adv. Funct. Mater., 2014). The thin active layer will be fabricated through shearing the solution suing a blade; the distance between the bottom of the blade and the surface of polymer substrate is set up about 200um, and the moving speed is about 1-20 mm/min depending on the solvents (toluene, xylene, mesitylene et al.), solute concentration (0.5-2 wt%) and substrate temperature (room temperature to 200 ℃). Finally, insulating layer and gate electrodes will be printed.
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