Daisuke Kumaki

Find an error

Name:

Organization: Yamagata University

Department: Research Center for Organic Electronics

Title:

Chemicals
References

Inkjet-printed copper electrodes using photonic sintering and their application to organic thin-film transistors

Co-reporter:Shohei Norita, Daisuke Kumaki, Yu Kobayashi, Tsubasa Sato, Kenjiro Fukuda, Shizuo Tokito

Organic Electronics 2015 Volume 25() pp:131-134

Publication Date(Web):October 2015

DOI:10.1016/j.orgel.2015.06.026

•Low thermal damage sintering process using Xe flash lamp was investigated.•Pentacene TFT with printed Cu electrodes showed the mobility of 0.13 cm2/Vs.•The crystal grain growth of pentacene near the printed Cu electrodes was studied.We report on copper (Cu) electrodes fabricated with inkjet-printed nanoparticle inks that are photonic sintered on a polymer dielectric layer and their application to source and drain electrodes in organic thin-film transistor (TFT). By using photonic sintering with a radiant energy density of 9 J/cm2, printed Cu nanoparticle layers on a glass substrate showed very low electrical resistivity levels of 7 μΩ cm. By optimizing the sintering conditions on polymer dielectric, the pentacene-based TFT using these printed Cu electrodes showed good mobility levels of 0.13 cm2/Vs and high on/off current ratios of about 106. In addition, we revealed that the crystal grain growth of pentacene near the printed Cu electrodes was inhibited by the thermal damage of polymer underlayer due to the high radiant energy density of the intense light.

Improvement of mechanical durability on organic TFT with printed electrodes prepared from nanoparticle ink

Co-reporter:Tomohito Sekine, Hideaki Ikeda, Akifumi Kosakai, Kenjiro Fukuda, Daisuke Kumaki, Shizuo Tokito

Applied Surface Science 2014 Volume 294() pp:20-23

Publication Date(Web):1 March 2014

DOI:10.1016/j.apsusc.2013.12.168

Abstract

We investigated a mechanism of improving adhesiveness depending on sintering temperature for printed silver (Ag) electrodes prepared from nanoparticle ink on an insulating polymer layer as the under layer. The adhesion strength significantly improved by sintering the Ag electrodes at a temperature above the glass transition temperature (T_g) of the polymer layer. In the sample with improved adhesiveness, the interfacial fusion between the printed Ag electrodes and polymer layer was observed in a cross sectional scanning electron microscope image. Based on this mechanism, we have successfully demonstrated the improvement in mechanical durability of organic thin-film transistors (TFTs) with printed Ag electrodes. The degradation of the organic TFTs after applying bending stress was significantly suppressed by interfacial fusion.

Reduced contact resistance and highly stable operation in polymer thin-film transistor with aqueous MoOx solution contact treatment

Co-reporter:Daisuke Kumaki, Yoshihide Fujisaki, Shizuo Tokito

Organic Electronics 2013 Volume 14(Issue 2) pp:475-478

Publication Date(Web):February 2013

DOI:10.1016/j.orgel.2012.12.002

We report on a newly developed solution process using MoO3 for reducing source and drain (S/D) electrodes in organic thin-film transistor (TFT). By taking advantage of the difference in surface wettability between the gate dielectric layer and the S/D electrodes, the electrode treatment using the MoOx solution was applied to polymer TFT with short channel lengths less than 10 μm. The contact resistance was noticeably reduced at the interface of the S/D electrodes in a polymer TFT using a pBTTT-C16. Furthermore, the field effect mobility for this TFT was enhanced from 0.03 to 0.1 cm2/V s. Most notably, the threshold voltage (Vth) shift under gated bias stress was less than 0.2 V after 105 s, which is comparable to that of conventional poly crystalline Si TFT.Graphical abstractHighlights► New solution process by using aqueous MoOx solution was developed for electrode treatment. ► Polymer transistor showed the mobility of 0.1 cm2/V s. ► Contact resistance was reduced to approximately one-sixth by using aqueous MoOx solution. ► The threshold voltage shift under gated bias stress was less than 0.2 V after 105 s.