Browsing by Author "Tsao, Hsiang-Yen"

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2,2 '-Bis(trifluoromethyl)biphenyl as a building block for highly ambient-stable, amorphous organic field-effect transistors with balanced ambipolarity
(2016-01-01)
Chaing, Chi-Jui
;
Chen, Jyh-Chien
;
Kuo, Yu-Ju
;
Tsao, Hsiang-Yen
;
Wu, Kuan-Yi
Novel conjugated polymers, PBPV-TPA, PBPV-CBZ, PBPV-MEH and PBPV-FLO, consisting of trifluoromethyl-substituted biphenyl (2,2'-bis(trifluoromethyl)biphenyl, CF3-BP) as the acceptor with various aromatic donors (triphenylamine TPA, carbazole CBZ, 2-(2-ethylhexyloxy)-5-methoxybenzene MEH and fluorene FLO, respectively) have been successfully synthesized. Their amorphous features, confirmed by wide-angle X-ray scattering, small-angle X-ray scattering and atomic force microscopy, are attributed to lateral side chains on the CBZ, MEH and FLO units, and the propeller geometry of the TPA unit. By integration of CF3-BPs into the polymer backbone, the ambipolarities and well-balanced charge mobilities of OFETs based on these polymers were successfully demonstrated. OFETs based on PBPV-FLO exhibit the highest hole mobility of 0.0152 cm(2) V-1 s(-1) and electron mobility of 0.0120 cm(2) V-1 s(-1). In addition, these OFETs also exhibit annealing-free characteristics and ambient stability. The OFET performance without encapsulation remained nearly unchanged in ambient conditions for up to 90 days. This could be attributed to the enhanced oxidative stability from their relatively deep HOMO energy levels and better moisture resistance from the trifluoromethyl substitution. Considering the ambipolar, annealing-free and ambient-stable properties of these CF3-BP-based amorphous conjugated polymers, the electron-accepting CF3-BP unit can be considered as a promising building block in preparing the easily processable conjugated polymers used in high-stability optoelectronic applications.
2,2 \'-Bis(trifluoromethyl)biphenyl as a building block for highly ambient-stable, amorphous organic field-effect transistors with balanced ambipolarity
(2016-01-01)
Chaing, Chi-Jui
;
Chen, Jyh-Chien
;
Kuo, Yu-Ju
;
Tsao, Hsiang-Yen
;
Wu, Kuan-Yi
Novel conjugated polymers, PBPV-TPA, PBPV-CBZ, PBPV-MEH and PBPV-FLO, consisting of trifluoromethyl-substituted biphenyl (2,2\'-bis(trifluoromethyl)biphenyl, CF3-BP) as the acceptor with various aromatic donors (triphenylamine TPA, carbazole CBZ, 2-(2-ethylhexyloxy)-5-methoxybenzene MEH and fluorene FLO, respectively) have been successfully synthesized. Their amorphous features, confirmed by wide-angle X-ray scattering, small-angle X-ray scattering and atomic force microscopy, are attributed to lateral side chains on the CBZ, MEH and FLO units, and the propeller geometry of the TPA unit. By integration of CF3-BPs into the polymer backbone, the ambipolarities and well-balanced charge mobilities of OFETs based on these polymers were successfully demonstrated. OFETs based on PBPV-FLO exhibit the highest hole mobility of 0.0152 cm(2) V-1 s(-1) and electron mobility of 0.0120 cm(2) V-1 s(-1). In addition, these OFETs also exhibit annealing-free characteristics and ambient stability. The OFET performance without encapsulation remained nearly unchanged in ambient conditions for up to 90 days. This could be attributed to the enhanced oxidative stability from their relatively deep HOMO energy levels and better moisture resistance from the trifluoromethyl substitution. Considering the ambipolar, annealing-free and ambient-stable properties of these CF3-BP-based amorphous conjugated polymers, the electron-accepting CF3-BP unit can be considered as a promising building block in preparing the easily processable conjugated polymers used in high-stability optoelectronic applications.
Ambient-Stable, Annealing-Free, and Ambipolar Organic Field-Effect Transistors Based on Solution-Processable Poly(2,2 \'-bis(trifluoromethyl)biphenyl-alt-2,5-divinylthiophene) without Long Alkyl Side Chains
(2015-01-28)
Chiang, Chi-Jui
;
Chen, Jyh-Chien
;
Tsao, Hsiang-Yen
;
Wu, Kuan-Yi
;
Wang, Chien-Lung
An ambipolar conjugated polymer CF3-PBTV, poly(2,2-bis(trifluoromethyl)biphenyl-alt-2,5-divinylthiophene), consisting of thienylenevinylene as the donor and trifluoromethyl-substituted biphenyl as the acceptor has been successfully synthesized. CF3-PBTV shows solution-processability without electrically insulating long alkyl side chains. Grazing incidence X-ray diffraction results suggest a nearly equal population of flat-on and end-on domains in CF3-PBTV thin film. The excellent ambipolarity of CF3-PBTV is demonstrated by well-equivalent charge mobilities of 0.065 and 0.078 cm(2) V-1 s(-1) for p- and n-channel, respectively. The organic field-effect transistors (OFET) also shows very high on/off ratio (approximate to 10(7)) which is attributed to the relatively large bandgap and low-lying highest occupied molecular orbital (HOMO) of CF3-PBTV. The OFET performance barely changes after the device is stored in ambient conditions for 90 days. The ambient-stability is attributed to the enhanced oxidative stability from its low-lying HOMO and the better moisture resistance from its fluorine contents. The performance of CF3-PBTV based OFET is annealing independent. It is noteworthy that the solution-processable, ambipolar, and thienylenevinylene-containing conjugated polymer without any long alkyl side chains is reported for the first time. And to the best of our knowledge, it is the first ambient-stable, annealing-free OFET with well-equivalent ambipolarity.