非富勒烯受體/奈米碳管複合材料：分子設計到熱電應用

Abstract

隨著科技和經濟的蓬勃發展，人們開始回頭反思過去以經濟成長為唯一指標的發展模式，使綠色能源逐漸受到重視。熱電效應能直接將廢熱轉換成電能，相比其他發電方式能大幅減少損耗且不會排放溫室氣體，成為備受關注的發電方式。熱電發電效率主要由導電度、賽貝克係數、熱導率和工作溫度決定，各項參數間具有較強的關聯性，同時優化各參數成為最主要的挑戰。為了最佳化熱電發電效率，使用有機/無機奈米複合材料可以利用有機和無機材料各自的優勢，已成為有效得到提高熱電優值(zT)材料的方法。本研究介紹兩種新型熱電複合材料系統，透過混合非富勒烯受體和單壁奈米碳管，得到具有高zT的熱電元件。 第一個研究中，非富勒烯受體聚合物(polymerized non-fullerene acceptor, PNFA)具有較佳的載子遷移率及共軛性質，顯示其在熱電領域的應用潛力。透過改變PNFA的中央核心結構，調控PNFA和單壁奈米碳管(single-walled carbon nanotube, SWCNT)間的作用力大小，製得同時具有高導電度和高賽貝克係數的P型熱電材料，最佳化zT可達到0.29。使用N-DMBI後摻雜可得到N型熱電元件，並將其與原P型材料串接，製成由5對P-N元件串聯而成的可撓曲熱電發電機。在兩端溫差為45 K時，輸出電壓為20.8 mV和輸出功率為109.3 nW。此研究透過調控PNFA的中央核心結構，以達成室溫範圍高zT的P型熱電複合材料，並闡述PNFA中央核心結構與熱電性能間的關聯性，開創PNFA有機熱電材料系統的研究。 第二個研究中，離子化非富勒烯受體(ionized Non-Fullerene Acceptor, iNFA)同時具有大量芳香環共軛結構和在主鍊上的離子結構，預期除了可以良好的分散SWCNT，也可以透過離子結構有效的摻雜SWCNT。透過優化iNFA的重量比例，成功製作出具有高導電度和高賽貝克係數的N型熱電材料，最佳化zT為9.2×10-3，為純SWCNT的約八倍。利用不同性質的NFA/CNT複合材料製作出P型與N型熱電元件，並串接5對P-N元件製成可撓曲熱電發電機，在兩端溫差為45 K時，輸出電壓為21.4 mV和輸出功率為214.3 nW。此研究利用全新的NFA與SWCNT混合，製作出P型及N型的熱電複合材料，並闡述NFA的結構與熱電性能間的關聯性，開創NFA有機熱電材料系統的研究。

With rapid technological and economic progress, development models are shifting from growth-driven to sustainable, with green energy as a key focus. Thermoelectric conversion directly transforms waste heat into electricity, reducing energy loss and greenhouse gas emissions. However, optimizing thermoelectric efficiency is challenging due to the strong interdependence of electrical conductivity, Seebeck coefficient and thermal conductivity. Organic/inorganic nanocomposites, which combine the strengths of both material types, have emerged as a promising strategy to enhance the thermoelectric figure of merit (zT). This study presents two novel thermoelectric composites based on blends of non-fullerene acceptors (NFAs) and single-walled carbon nanotubes (SWCNTs), achieving high zT values. In first study, polymerized NFAs (PNFAs) exhibit high charge-carrier mobility and extended conjugation, demonstrating significant potential for thermoelectric applications. By engineering the central core structure of PNFA, we modulated the interaction strength between PNFA and SWCNTs. This optimization yielded p-type thermoelectric materials with concurrently high electrical conductivity and Seebeck coefficient, achieving a peak zT of 0.29. Subsequent n-type doping with N-DMBI enabled the fabrication of n-type devices. These p- and n-type materials were integrated into a flexible thermoelectric generator comprising five serially connected p-n couples. At a temperature gradient (ΔT) of 45 K, the device delivered a maximum output voltage of 20.8 mV and a peak power output of 109.3 nW. This work establishes the correlation between PNFA’s core structure and thermoelectric performance, pioneering the study of PNFA-based organic thermoelectric systems. In second study, ionic NFAs (iNFAs) feature both extended aromatic conjugation and ionic groups integrated directly into the molecular backbone. This unique design enables effective SWCNT dispersion and efficient doping. By optimizing the iNFA weight ratio, we developed n-type thermoelectric materials with high electrical conductivity and Seebeck coefficient, achieving a maximum zT of 9.2 × 10⁻3—eightfold higher than that of pristine SWCNTs. Using iNFA/CNT composites with tailored properties, we fabricated both p-type and n-type modules. A flexible generator integrating five p-n couples yielded a maximum voltage of 21.4 mV and a peak power output of 214.3 nW at ΔT= 45 K. This study demonstrates the structure-property relationship of iNFAs and pioneers the development of iNFA-based thermoelectric systems.