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Ichikawa M.,Shinshu University | Ichikawa M.,Japan Science and Technology Agency | Yokota Y.,Shinshu University | Jeon H.-G.,Shinshu University | And 4 more authors.
Organic Electronics: physics, materials, applications | Year: 2013

In this study, several naphthalene tetracarboxylic acid diimide (NTCDI) derivatives substituted at the N and N′ positions with long normal alkyl chains of different lengths were evaluated as soluble n-type organic thin-film transistor (TFT) materials. NTCDI derivatives with diundecyl (NTCDI-C11), didodecyl (NTCDI-C12), and ditridecyl (NTCDI-C13) exhibited acceptable solubility in chloroform, and their TFTs showed typical n-type TFT performance with relatively high field effect electron mobility (∼0.2 cm2/V s) after annealing at a workable temperature of 150 °C. Although NTCDI with dioctyl (NTCDI-C8) showed good solubility in chloroform, the TFT performance of this material was highly inferior to that of NTCDI-C11, NTCDI-C12, or NTCDI-C13. We could not anneal NTCDI-C8 thin films at workable temperatures in vacuo because of sublimation of the material from the substrates. In contrast, NTCDI with dipentadecyl (NTCDI-C15) and dioctadecyl (NTCDI-C18) exhibited both poor solubility for chloroform and poor TFT performance. In short, these compounds are not suitable as soluble n-type organic TFT materials. © 2012 Elsevier B.V. All rights reserved.

Jeon H.-G.,Shinshu University | Oguma N.,Dainichiseika Color and Chemicals Manufacturing Co. | Hirata N.,Dainichiseika Color and Chemicals Manufacturing Co. | Ichikawa M.,Shinshu University | Ichikawa M.,Japan Science and Technology Agency
Organic Electronics: physics, materials, applications | Year: 2013

Here we propose and demonstrate a new approach to wet-processed organic thin-film transistors utilizing highly-stable colloids of small molecular organic semiconductors prepared by laser ablation technique. Highly stable N,N′-ditridecyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C13) colloids of 0.1 wt% concentration were prepared successfully by laser ablation technique in acetonitrile. Mean particle size of the prepared PTCDI-C13 colloid measured by dynamic light scattering method was smaller than 50 nm which is also confirmed by a transmission electron microscope observation. By simple drop-casting of prepared PTCDI-C13 colloids, typical n-type OTFTs with good saturation properties were fabricated successfully. The highest electron mobility was 1.1 × 10-3 cm2/Vs and increased up to 0.027 cm2/Vs by post-annealing treatment. © 2012 Elsevier B.V. All rights reserved.

Jeon H.-G.,Shinshu University | Jeon H.-G.,Ehime University | Yokota Y.,Shinshu University | Hattori J.,Shinshu University | And 5 more authors.
Applied Physics Express | Year: 2012

The authors report a novel perylene derivative [N,N′-bis(3- dodecyloxy-propyl)-perylene tetracarboxylic diimide, PTCDI-C3OC12] as a soluble high-performance n-type organic semiconductor. The solubility of the PTCDI derivative was increased sufficiently to be handled using wet processes by inserting ether groups in side alkyl chains of the PTCDI derivative. The highest electron mobility obtained for a spin-coated PTCDI-C3OC12 film was 0.52 cm 2/(V·s) with a very low threshold voltage of ca. 2 V. This high performance of PTCDI-C3OC12 is explained by the large grain size with an appropriate molecular packing pattern and tight intergrain connections. © 2012 The Japan Society of Applied Physics.

Jeon H.-G.,Shinshu University | Hattori J.,Shinshu University | Kato S.,Shinshu University | Oguma N.,Dainichiseika Color and Chemicals Manufacturing Co. | And 4 more authors.
Journal of Applied Physics | Year: 2010

The authors report that thermal treatment effect on various N, N′ -dialkyl-3,4,9,10-perylene tetracarbxylic diimides [PTCDI-Cn, alkyl-dodecyl (n=12), butadecyl (n=14), octadecyl (n=18)] thin-film transistors (TFTs) depends on the substituted alkyl chain length. It is clearly demonstrated that there are two kinds of molecular movements during the thermal treatment on PTCDI films; molecular rearrangement in the same layer and molecular migration from the lower layer to the upper layer. The former is directly related to the grain growth and can be controllable by applying an external electric field. The latter is also related not only to the grain growth but also to the formation of cracks between grains. These two movements show opposite dependence on the alkyl chain length during the thermal treatment; the former is more active in longer alkyl chain, but the latter in shorter one. However, they also have opposite effect to TFT performance, and PTCDI films with longer alkyl chains have great advantage on TFT performance for the thermal treatment. Consequently, PTCDI-C18 TFTs show the highest electron mobility as large as 1.2cm2 /V s after the thermal treatment at 140 °C. © 2010 American Institute of Physics.

Hiraga T.,Japan National Institute of Advanced Industrial Science and Technology | Ueno I.,Japan National Institute of Advanced Industrial Science and Technology | Shiga N.,Trimatiz Ltd. | Watanabe H.,Inter Energy Co. | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

A versatile optically-gated optical switch using an organic-dye is suitable for light-path switching in an optical communication for various wavelengths of a signal-light. An organic dye for absorbing a gating-light combined with a high-boiling solvent for forming a thermal-lens is properly selected choosing a wavelength of both a gating- and a signal-light. The incidence gating-light passed through a short focal-length lens is absorbed around the focal point and form high-temperature region in the high-boiling solvent, which refract a simultaneously incidence signal-light by a thermal-lens effect. Mechanism of forming a thermal-lens and refracting the signal-light is discussed. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

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