Browsing by Author "Takimiya, Kazuo"

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2-V operated flexible vertical organic transistor with good air stability and bias stress reliability
(2017-11-01)
Huang, Kuan-Min
;
Lin, Hung-Cheng
;
Kawashima, Kazuaki
;
Osaka, Itaru
;
Zan, Hsiao-Wen
In this work, we demonstrated a vertical organic transistor using air-stable material to exhibit good lifetime, good bias-stress reliability, and low operation voltage on a flexible plastic substrate in air ambient. With a synthesized NTz-based semiconducting polymer, the proposed space-charge-limited transistor (SCLT) delivers high on-off current ratio of 160000 and high output current density of 10 mA/cm(2) at about 2 V. Without encapsulation, the proposed transistor keeps stable current-voltage relationship for 180 days and has only 0.1 V threshold voltage shift after 5000 s bias stress. No significant degradation can be observed after 1000-times bending and a maximum gain of 14 can be obtained when connecting the flexible transistor with a resistor to form an inverter. (C) 2017 Elsevier B.V. All rights reserved.
Angular-Shaped 4,9-Dialkyl - and -Naphthodithiophene-Based Donor-Acceptor Copolymers: Investigation of Isomeric Structural Effects on Molecular Properties and Performance of Field-Effect Transistors and Photovoltaics
(2015-10-14)
Cheng, Sheng-Wen
;
Chiou, De-Yang
;
Tsai, Che-En
;
Liang, Wei-Wei
;
Lai, Yu-Ying
Two angular-shaped 4,9-didodecyl -aNDT and 4,9-didodecyl -aNDT isomeric structures have been regiospecifically designed and synthesized. The distannylated -aNDT and -aNDT monomers are copolymerized with the Br-DTNT monomer by the Stille coupling to furnish two isomeric copolymers, PNDTDTNT and PNDTDTNT, respectively. The geometric shape and coplanarity of the isomeric -aNDT and -aNDT segments in the polymers play a decisive role in determining their macroscopic device performance. Theoretical calculations show that PNDTDTNT possesses more linear polymeric backbone and higher coplanarity than PNDTDTNT. The less curved conjugated main chain facilitates stronger intermolecular - interactions, resulting in more redshifted absorption spectra of PNDTDTNT in both solution and thin film compared to the PNDTDTNT counterpart. 2D wide-angle X-ray diffraction analysis reveals that PNDTDTNT has more ordered -stacking and lamellar stacking than PNDTDTNT as a result of the lesser curvature of the PNDTDTNT backbone. Consistently, PNDTDTNT exhibits a greater field effect transistor hole mobility of 0.214 cm(2) V-1 s(-1) than PNDTDTNT with a mobility of 0.038 cm(2) V-1 s(-1). More significantly, the solar cell device incorporating the PNDTDTNT:PC71BM blend delivers a superior power conversion efficiency (PCE) of 8.01% that outperforms the PNDTDTNT:PC71BM-based device with a moderate PCE of 3.6%.