雷射誘導石墨烯修飾金屬網/PDMS柔性電極在摩擦奈米發電機上之研究

Abstract

摩擦奈米發電機可收集環境中的微小能量，將機械能轉換為電能，來源包括海浪、人體運動、風力等，適用於多種環境，具再生能源優勢。目前提升TENG電性輸出的研究多集中於摩擦材料的選擇、改性、極化注入及表面結構改善，較少探討電極的影響。2020年，Zhao等人提出在摩擦材料上直接生成石墨烯電極，避免因功函數差異產生初始電荷影響輸出，但其使用的紙基材與聚醯亞胺難以進一步改性。相比之下，PDMS作為電負性材料，不僅可透過雷射誘導生成石墨烯提升電性輸出，還具化學穩定性及可設計性，適合結合表面改性與結構設計。 本論文利用藍光445nm雷射對PDMS進行雷射誘導生成石墨烯作為電極，因PDMS對可見光的吸收率較差，透過添加石墨粉末提高可見光吸收率使其降低對焦系統的要求讓在雷射誘導過程有更好的轉換，除此之外我們添加金屬網提供石墨烯更好的導電網絡與機械性質。我們透過量測開路電壓和在負載下的電壓，觀察石墨烯/金屬網複合電極對摩擦奈米發電機電性輸出影響，石墨烯電極與介電層功函數接近減少介面產生初始電荷轉移，使表面電荷交換效率提升，本研究透過添加高介電常數奈米顆粒形成複合材料介電層，提高介電層有效電容值使摩擦奈米發電機提升電壓輸出，除此之外也透過添加碳源TEG(三乙二醇)讓生成的石墨烯更加穩定且電阻越小，隨然透過添加TEG使電極電導率更好，但我們也觀察到TEG在摩擦表面對電性輸出的負面影響，我們透過旋塗一層很薄的PDMS在介電層表面，避免TEG在表面影響表面電荷密度，有效改善TEG對於電性輸出的影響，我們有效同時利用雷射誘導石墨烯電極的優勢在PDMS上並證明對摩擦材料改性的可行性。我們量測此摩擦奈米發電機的機械性質與電氣性質，不同介電層厚薄度、不同負載電性輸出的影響。最後測量有無添加金屬網對於電性輸出的影響，金屬網提升了石墨烯電極的耐用性以及機械性質，避免介電層在雷射燒蝕的過程中因為熱導致彎曲變形。

With the rise of the Internet of Things (IoT), IoT devices require a continuous and stable energy supply. Most IoT devices rely on traditional chemical batteries, but these batteries have limited lifespans and require frequent replacement. As a result, self-powered sensors have become a research trend. Triboelectric nanogenerators (TENGs) can harvest small amounts of energy from the environment and convert mechanical energy into electrical energy. The mechanical energy can come from sources such as ocean waves, human motion, wind, and vibrations, making TENGs less constrained by environmental conditions. Therefore, TENGs offer significant advantages in the field of renewable energy. Most current studies on improving the electrical output of TENGs focus on selecting triboelectric materials, modifying triboelectric materials, injecting polarization charges, or optimizing surface structures. However, relatively few studies have explored the impact of electrodes on the electrical output of TENGs. In 2020, Zhao et al. proposed a method to directly generate graphene electrodes on triboelectric materials. These carbon-based electrodes avoid the initial charge caused by the work function difference between triboelectric materials and traditional metal electrodes, which could otherwise affect electrical output. However, their selected triboelectric materials—paper-based substrates and polyimide—are relatively difficult to modify or structurally optimize to enhance electrical output. PDMS is an excellent electronegative triboelectric material that can also generate graphene through laser induction. PDMS is chemically stable, easy to process, and allows for both the enhanced electrical output provided by graphene electrodes and further modifications or surface structural designs to improve performance. In this study, a 445 nm blue laser was used to induce graphene formation on PDMS, and a metal mesh was added to provide a better conductive network and improved mechanical properties. Additionally, high-dielectric-constant nanoparticles were incorporated to enhance electrical output. Moreover, triethylene glycol (TEG) was introduced as a carbon source to improve the stability and reduce the resistance of the generated graphene. However, we observed a negative impact of TEG on the triboelectric surface's electrical output. To address this issue, a thin PDMS layer was spin-coated to prevent TEG from migrating to the surface, effectively mitigating its adverse effects. Finally, we measured the mechanical and electrical properties of the fabricated TENG, investigating the effects of different dielectric layer thicknesses, varying load conditions, the presence of a metal mesh, and other factors on its electrical output.