Browsing by Author "Tsai, Tsung-Che"

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A facile dedoping approach for effectively tuning thermoelectricity and acidity of PEDOT:PSS films
(2014-03-01)
Tsai, Tsung-Che
;
Chang, Hsiu-Cheng
;
Chen, Chun-Hua
;
Huang, Yi-Chia
;
Whang, Wha-Tzong
A facile approach namely controlling the pH level of 5 wt% dimethyl sulfoxide (DMSO) doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) solution with sodium hydroxide (NaOH) was utilized for the first time in successfully optimizing the thermoelectric conversion efficiency of PEDOT:PSS films. The largely varied Seebeck coefficients and electrical conductivities of the pH controlled PEDOT:PSS films which could thus construct a beneficial curve for locating the optimized power factor are clearly shown from the significant changes of the carrier concentration via the dedoping of PEDOT. The correlation between pH value and carrier concentration as well as the power factor is experimentally found with numerical description covering a full pH range. The applied technique and the resulting optimized thermoelectric properties and possible bio-compatibility not only provide a fundamental understanding of the thermoelectric conducting polymers but widely disclose a variety of potential applications in the future. (C) 2014 Elsevier B. V. All rights reserved.
A Facile Surface Treatment Utilizing Binary Mixtures of Ammonium Salts and Polar Solvents for Multiply Enhancing Thermoelectric PEDOT: PSS Films
(2014-12-01)
Tsai, Tsung-Che
;
Chen, Tsung-Han
;
Chang, Hsiu-Cheng
;
Chen, Chun-Hua
;
Huang, Yi-Chia
High-performance vertically stacked bottom-gate and top-gate polycrystalline silicon thin-film transistors for three-dimensional integrated circuits
(2012-11-01)
Lee, I-Che
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Tsai, Tsung-Che
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Tsai, Chun-Chien
;
Yang, Po-Yu
;
Wang, Chao-Lung
The three-dimensional CMOS inverter with top-gate (TG) poly-Si thin film transistors (TFTs) vertically stacked on the bottom-gate (BC) poly-Si TFTs have been proposed to achieve high-performance characteristics via excimer laser crystallization (ELC) for the first time. Under an appropriate laser irradiation energy density, the silicon grain growth could be controlled from the sidewalls of the bottom-gate structure and thus the high-quality laterally grown poly-Si film with single perpendicular grain boundary in the channel would be formed for the BC TFTs. In addition, a simple ELC method was also utilized to the top-layered poly-Si film for TG TFTs as compared with solid-state-crystallized (SPC) ones. As a result, the field-effect mobilities of the proposed n-type BC and p-type TG TFTs could be significantly increased to be 390 and 131 cm(2)/V s, respectively, in contrast to 32.3 and 14.7 cm(2)/V s for the SPC ones, accordingly. Furthermore, such three-dimensional (3-D) TFT have also been employed to demonstrate the inverter devices and is suitable for future 3-D ICs as well as system-on-panel applications. (c) 2012 Elsevier Ltd. All rights reserved.
Smart assembling of multi-scaled functional interfaces in thermoelectric Ga2Te3/Te hetero-nanocomposites
(2014-01-01)
Chang, Hsiu-Cheng
;
Chiang, Ming-Hsiu
;
Tsai, Tsung-Che
;
Chen, Tsung-Han
;
Whang, Wha-Tzong
We describe an innovative concept and facile approach in fabricating laterally assembled Ga2Te3/Te binary nanocomposite films, which comprise two-dimensional quasi-periodic Ga2Te3 nanoassemblies surrounded by interlocking highly-conductive Te single crystals for comprehensively establishing subnanoto micro-scaled multi-style versatile interfaces. The distinct Ga2Te3/Te nanocomposite film exhibits a power factor that is about 60 times higher than the reported conventional Ga2Te3 and Te materials, mainly due to the 2- to 3-order improved electrical conductivity and the comparable Seebeck coefficient.
Widely variable Seebeck coefficient and enhanced thermoelectric power of PEDOT:PSS films by blending thermal decomposable ammonium formate
(2011-12-01)
Tsai, Tsung-Che
;
Chang, Hsiu-Cheng
;
Chen, Chun-Hua
;
Whang, Wha-Tzong
;
材料科學與工程學系
The doping effects of thermal decomposable ammonium formate (AF) from 5 to 50 wt.% on the electrical conductivity, Seebeck coefficient, and microstructures of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films have been investigated for the first time for modern thermoelectric applications. It has been found that the Seebeck coefficient can be effectively tuned in a very wide range by varying the AF doping concentration, where a maximum value of 436.3 mu V/K was obtained, i.e., similar to 40 times higher in magnitude than the pure PEDOT:PSS films prepared with same processes. The greatly enhanced Seebeck coefficient is considered to be the result of reducing the carrier concentration, as evidenced by the Hall measurement. In addition, AF also plays an important role in the formation of the closed or open pores and channels within the films for phonon scattering, as can be clearly observed in the SEM images. The present work provides a new procedure to effectively control the Seebeck coefficient as well as the microstructures of PEDOT:PSS polymer by a simple blending approach with suitable thermal steps, which has not previously been reported. (C) 2011 Elsevier B.V. All rights reserved.