複合孔洞薄膜之熱電與光熱電元件開發

Abstract

熱電材料能夠將熱能直接轉換為電能，近年來受到高度重視，特別適用於低溫廢熱回收與穿戴式裝置之電力供應。奈米碳管具備優異的導電性、柔韌性與穩定性，被視為具潛力的候選材料。然而，其高熱導率與分散性不良限制了實際應用效能，因此開發具功能性的複合材料成為提升其熱電表現的關鍵策略。本研究第一部分探討將兩種具備不同表面官能基的鋯基二維金屬有機框架材料，分別為親水性的 ZrBTB 與疏水性的 ZrBTB-BA，導入至 CNT 中以提升其分散性並改善熱電性質。藉由調整溶劑選擇（如 DCB 與 NMP），有效調控 CNT 的載子極性。其中，CNT/ZrBTB-BA 複合材料在 p 型與 n 型狀態下分別展現出 395.2 與 330.8 μW m–1 K–2 的高功率因子，並顯著提升其熱電優值。進一步將此材料應用於柔性熱電發電元件中，顯示其於可攜式與穿戴式能源裝置中的實用潛力。第二部分進一步結合光熱效應與熱電效應，開發具備光熱電功能的複合材料系統。透過後修飾方式，將染料 N719 固定於ZrBTB表面，成功合成具備寬波段可見光吸收能力的 ZrBTBD，並與奈米碳管混合製得均勻複合材料。搭配 N-DMBI 摻雜後，實現了 n 型傳輸行為的調控。所製得之 C/ZrBTBD 複合材料在 p 型與 n 型，分別達到 465.7 與 363.1 μW m–1 K–2 的高功率因子。在 100 mW cm–2 照光條件下，材料表面溫度由 47.3 °C 上升至 51.2 °C，對應之zT亦顯著提升。進一步組裝成柔性光熱電元件，能輸出 12.3 mV 的開路電壓與 365.4 nW 的最大功率，並成功應用於穿戴式裝置中，展現其在戶外自然光與室內皆具穩定運作能力，驗證其於多元環境中供電的實用可行性。整體而言，本研究成功建構一系列以 MOFs 與奈米碳管為基礎的複合熱電材料，無論應用於熱電或光熱電系統皆展現出色表現。為未來可撓曲式與自供電電子元件開啟新的發展方向。

Thermoelectric (TE) materials, capable of directly converting heat into electricity, have attracted significant attention in recent years, especially for applications in low-temperature waste heat recovery and power supply for wearable devices. Carbon nanotubes (CNTs), known for their excellent electrical conductivity, flexibility, and stability, are considered promising candidates. However, their inherently high thermal conductivity and poor dispersibility limit their practical performance. Therefore, the development of functional composite materials has become a key strategy to improve their TE properties. In the first part of this study, two zirconium-based two-dimensional metal–organic frameworks (MOFs) with different surface functionalities, namely hydrophilic ZrBTB and hydrophobic ZrBTB-BA, were incorporated into CNTs to enhance dispersion and TE performance. By adjusting solvent selection, such as using DCB or NMP, the carrier polarity of CNTs was effectively modulated, enabling the preparation of both p-type and n-type TE composites. Among these, the CNT/ZrBTB-BA composites achieved high power factors of 395.2 and 330.8 μW m–1 K–2 for p-type and n-type behavior, respectively, along with significant improvements in figure of merit (zT). These materials were further applied to flexible thermoelectric generators (TEG), demonstrating promising potential for portable and wearable energy applications. The second part of this study focuses on integrating photothermal (PT) and TE effects to develop a composite system with photothermoelectric (PTE) functionality. Through post-synthetic modification, the N719 dye was anchored onto the surface of ZrBTB to form ZrBTBD, which exhibits broad visible light absorption. This material was uniformly combined with CNTs to form a composite with enhanced light-harvesting ability. With the addition of N-DMBI as a dopant, n-type TE behavior was successfully achieved. The resulting C/ZrBTBD composites exhibited high power factors of 465.7 and 363.1 μW m–1 K–2 under p-type and n-type conditions, respectively. Under 100 mW cm–2 illumination, the surface temperature increased from 47.3 °C to 51.2 °C, accompanied by a notable enhancement in zT. A flexible photothermoelectric generators (PTEG) constructed from these composites generated an open-circuit voltage of 12.3 mV and a maximum power output of 365.4 nW. Its reliable operation under both indoor and outdoor conditions confirms its practical feasibility for power generation in various environments. In conclusion, this work successfully develops a series of composites based on MOFs and CNTs that demonstrate excellent performance in both TE and PTE systems. The incorporation of MOFs not only resolves dispersion and thermal management challenges of CNTs but also introduces additional tunability, paving the way for future advancements in flexible and self-powered electronic devices.