近年來由於壓電材料能夠於機械能和電能間互相轉換的性質而在電子應用 領域得到了廣泛之應用。其中壓電材料聚偏二氟乙烯(PVDF)具有出色的機械韌 性、重量輕和低介電常數等特性，是柔性電子產品中的支柱。然而工業製造的聚 壓電聚偏二氟乙烯中缺乏極性的電活性(electroactive)相而限制了其在壓電材料 中的潛在應用。在高分子基體中加入納米填料是增強極性相的有效方法。近期來， 人們因二維過渡金屬二硫化物(TMD)其獨特的結構和電性能而對可用於能源採 集的材料興趣日益濃厚。在本論文中，通過液相剝離(LPE)二硫化鉬(MoS2) 獲得 的少層的二維二硫化鉬(MoS2)，並將其引入聚偏二氟乙烯基質中使用溶劑澆鑄法 製造基於二硫化鉬/聚偏二氟乙烯的獨立式柔性壓電薄膜。
透過 X 光繞射(XRD)和穿透式電子顯微鏡(TEM)可證明二硫化鉬僅有少層 結構，而紫外光-可見光(UV-vis)估算出能帶約 1.88 eV。透過製造不同濃度剝離 的二硫化鉬的壓電複合薄膜來評估剝離的二硫化鉬奈米片對聚偏二氟乙烯的影 響。並透過傅里葉變換紅外光譜(FTIR)、拉曼光譜和 X 光繞射(XRD)研究了填料 含量效應引起的結構演變。結果顯示當添加 5wt%的二硫化鉬時，電活性相含量 提高到 77.9%。此外二硫化鉬/聚偏二氟乙烯複合薄膜的電學性質也藉由 LCR 量 測儀來分析。介電譜和電模量譜表明，添加二硫化鉬可增加載流子於聚偏二氟乙 烯中的遷移率。此外，二硫化鉬/聚偏二氟乙烯複合薄膜被用於製造壓電奈米發電機(PENG)傳感器裝置，並透過在衝擊測試方法下測量輸出電壓來評估其壓電 響應。結果顯示當添加 5wt%的二硫化鉬時，輸出電壓大大提高，大約是沒有二 硫化鉬填料的薄膜的 4.7 倍。總體結果表明，少層的二硫化鉬可藉由增加 β 相 和 γ 相晶體含量有效地誘導聚偏二氟乙烯的電活性相含量。此外，由添加二硫 化鉬誘導的電活性相的增加和電荷傳輸效率的提高造成的協同效應顯著地促進 了奈米發電機傳感器良好的壓電性能。

Piezoelectric materials have recently been widely used in the electronic application field due to their ability to interconvert mechanical and electrical energy. Because of its excellent mechanical flexibility, lightweight, and low dielectric constant, piezoelectric polyvinylidene fluoride (PVDF) is a desirable backbone for flexible electronics. However, the original industrial PVDF lacks a polar electroactive (EA) phase, which restricts its potential for use in piezoelectric materials. Including nanofiller in the polymer matrix is an effective method to enhance the polar phases. Recently, two-dimensional (2D) transition metal dichalcogenides (TMDs) have aroused increasing interest in fabricating energy harvest materials because of their unique structure and electric properties. In this thesis, a few layers of two-dimensional molybdenum disulfide (MoS2) were obtained by liquid-phase exfoliation (LPE) from bulk MoS2 and introduced into the PVDF matrix to fabricate the MoS2/PVDF-based free-standing and piezoelectric flexible film by solvent casting.
The exfoliated MoS2 (E-MoS2) nanosheets were proven by X-ray diffraction (XRD) and transmission electron microscopy (TEM) as a few layers, and ultraviolet- visible (UV-vis) was used to estimate the band gap energy of about 1.88 eV and its exfoliation. The effects of exfoliated MoS2 (E-MoS2) nanosheets on the PVDF’s piezoelectrical properties were evaluated by preparing the piezoelectric composite films with various concentrations of E-MoS2. The structure evolution concerning the filler content effect was investigated by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray diffraction (XRD). The EA phase content was improved to 77.9% when 5 wt% of E-MoS2 was added to the PVDF. The electrical properties of MoS2/PVDF composite films were analyzed by the LCR meter. The dielectric and electric modulus spectra demonstrate that the addition of E-MoS2 increases the mobility of charge carriers in MoS2/PVDF piezoelectric film. In addition, the MoS2/PVDF composite film was used to fabricate a piezoelectric nanogenerator (PENG) sensor device and evaluate the piezoelectric response by measuring the output voltage under the impact test method. The output voltage was greatly enhanced when 5 wt% of E-MoS2 was added and was about 4.7-fold higher than the film without the MoS2 filler. The overall results showed that the addition of E-MoS2 can effectively induce the EA phase fraction of PVDF by increasing β- and γ-phase crystalline content. Moreover, the synergetic effect caused by the increased EA phase and the improved charge transport ability significantly contributed to the good piezoelectric performance of the nanogenerator sensor.

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