Please use this identifier to cite or link to this item:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/88363
Title: | 有機熱電元件:材料合成、分析、穿戴式元件應用 Organic Thermoelectric Devices: Materials Synthesis, Characterization, Wearable Devices Application |
Authors: | 林彥廷 Yen-Ting Lin |
Advisor: | 劉振良 Cheng-Liang Liu |
Keyword: | 有機熱電,熱電化學電池,熱電發電機,導電高分子,水凝膠,穿戴式裝置, organic thermoelectric,thermoelectrochemical cells,thermoelectric generator,conducting polymer,hydrogel,wearable device, |
Publication Year : | 2023 |
Degree: | 碩士 |
Abstract: | 隨著環保意識抬頭,綠色能源已然成為不可或缺的能源供應來源,本研究包含薄膜高分子熱電以及膠態熱電化學電池都著重在有機熱電系統的效能提升,來實現更有效的熱到電能源轉換。首先,於第一篇研究,成功以噴塗法製備PEDOT:PSS熱電薄膜,並佐以EG跟MAI的兩步法後處理。EG後處理有效提高薄膜的電子導電度至1752.1 S cm–1,但保持著幾乎不變的Seebeck係數(15-17 μV K–1)。再第二步後處理,最佳化的0.05 M MAI溶於DMSO/DI water溶液處理可以達到功率因子(122.3 μW m–1 K–2),同時在此後處理步驟同時提升電子導電度至2226.8 S cm–1以及Seebeck係數22.8 μV K–1。值得關注的是,在所有噴塗製備的高分子熱電材料中此功率因子是目前最高的熱電效能表現。如此高效的熱電表現可以歸功於多樣的因素,其中包含後處理所造成的PEDOT與不導電PSS相分離、更容易共振的主鏈結構、較有排列性的PEDOT結晶以及較適化的能階偏移。同時將PEDOT:PSS噴塗在可饒曲的塑膠基板也保持極高的熱電表現,此概念驗證的穿戴式熱電發電機於溫差19.5 K時可產生12.1 nW cm–2的功率輸出密度。
第二篇研究則著重在熱電化學電池的開發,膠態熱電化學電池因為其可持續轉換低能廢熱並持續發電的特點,於穿戴式裝置的研究領域中凸顯。但過往的熱電化學電池研究都受困於其離子導電度的不足。因此本研究利用冷凍回放法製備三層網絡水凝膠(PAAM/PVA/CNF)作為膠態電化學電池的基材,並將此水凝膠浸入Fe(CN)63–/4–氧化還原對溶液中形成膠態電化學電池。根據最佳化的基材高分子比例調控以及氧化還原對溶液的浸泡時間,我們獲得極高的離子導電度555 mS cm–1,以及氧化還原對本質的熱功率(或稱Seebeck係數) 1.69 mV K–1。本研究進一步使用小角度X光散射發現水膠基材中高分子密集與鬆散的結構上相分離有利於離子傳遞,因此提高極高的離子導電度。最後將膠態電化學電池製備成熱電發電機矩陣,並且在溫差11.9 K時可提供28.7 μW的功率輸出。 綜合上述,兩篇研究皆在可饒曲熱電發電機以及穿戴式能源供應元件有十分出色的表現。這些研究對穿戴式熱電裝置的元件製備方法、材料分析以及效能提升方法都有清晰的發現與探討,對未來此領域的研究開創一條康莊大道。 Both research studies center around enhancing the performance of flexible thermoelectric devices specifically tailored for wearable applications. Firstly, polymer-based thermoelectric films comprising poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are successfully prepared through a spray coating technique, followed by a sequential, two-step post-treatment process involving ethylene glycol (EG) and a methylammonium iodide (MAI) solution. The ethylene glycol treatment significantly enhances the electrical conductivity of the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) film, resulting in a remarkable electrical conductivity (σ) of 1752.1 S cm–1, while the Seebeck coefficient (S) remains unchanged within the range of 15–17 μV K–1. In the second step, optimal utilization of a 0.05 M methylammonium iodide solution in dimethyl sofoxide / deionized water leads to a notable increase in the power factor (PF), reaching 122.3 μW m–1 K–2. Furthermore, this step contributes to a further enhancement in electrical conductivity (2226.8 S cm–1) and Seebeck coefficient (22.8 μV K–1). It is noteworthy that the achieved power factor is among the highest reported for spray-coated thermoelectric devices based on polymers. The observed performance improvement can be attributed to various factors, including the phase separation of non-conductive PSS from PEDOT, alterations in chain conformation, the preferential orientation of PEDOT crystallites, and manipulation of energy levels. The excellent thermoelectric performance of the prepared poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) films on a plastic substrate is verified through the implementation of a proof-of-concept thermoelectric generator (TEG), demonstrating a maximum power density of 12.1 nW cm–2 under the temperature difference of 19.5 K. Secondly, quasi-solid thermoelectrochemical cells (TECs) have emerged as a promising solution for wearable energy harvesting devices due to their ability to continuously convert low-grade heat into electricity. However, a significant challenge in achieving satisfactory TEC performance arises from the insufficient ion conductivity within the system. To address this issue, the present study proposes the utilization of a triple-network hydrogel consisting of polyacrylamide/poly(vinyl alcohol)/cellulose nanofiber (PAAM/PVA/CNF), synthesized using the freeze-thaw method. The thermogalvanic redox couple Fe(CN)63–/4– is employed as the electrolyte, combined with hydrogel soaking. Through optimization of the polymer composition and appropriate soaking time, a remarkable record-high ionic conductivity (σi) of 555 mS cm–1 is achieved, while the thermopower (α, or Seebeck coefficient) remains consistent at approximately 1.69 mV K–1, governed by the underlying redox reaction. Further insights into the system are obtained through small-angle x-ray scattering (SAXS) analysis, which reveals the presence of phase separation between polymer-rich and polymer-poor domains, contributing to the observed high ionic conductivity in the TECs. Additionally, the exceptional performance of the TEG array is demonstrated, showcasing a power output of 28.7 μW under a temperature difference of 11.9 K. Overall, both investigations emphasize the progress made in flexible thermoelectric technology and its diverse range of potential applications, including flexible thermoelectric generators and wearable power supply systems. These research endeavors offer valuable insights into the fabrication methodologies, material characteristics, and performance enhancements achieved in flexible thermoelectric devices, thereby paving the way for future advancements in this field. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/88363 |
DOI: | 10.6342/NTU202302098 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 材料科學與工程學系 |
Files in This Item:
File | Size | Format | |
---|---|---|---|
ntu-111-2.pdf Restricted Access | 6.37 MB | Adobe PDF |
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.