環境友善之葡萄糖類天然高分子於有機高分子太陽能電池的應用

Applications of Eco-friendly Glucose-Based Natural Polymers in Polymer Solar Cells

林柏辰(Po-Chen Lin)

指導教授 ： 闕居振

國立臺灣大學/工學院/化學工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202001243

摘要

近十年來，有機太陽能電池受益於其製程簡易、可撓性高以及成本低廉等特性而備受矚目。除了想辦法提升元件效率之外，部分研究者們最近把研究重心轉移至改善有機太陽能電池的材料與製程使之更為環保，並符合永續發展的精神。在這之中，由於生質材料其生物可降解、安全無毒以及生產便宜的特性，將生質材料使用於有機太陽能電池中成為熱門的研究方向。
因此，本研究中分析了葡萄糖類天然高分子：殼聚糖、甲基纖維素以及糊精作為有機太陽能電池中氧化鋅表面修飾層的可行性。由於適當的側鏈改質，這些天然高分子相比其他生質材料較易利用溶液製程以及具備較好的成膜性。此外，由於天然高分子在大自然中分布廣泛，使之跟其他常用的高分子修飾層材料相比成本更低。研究結果顯示出葡萄糖類天然高分子的構形是影響其衍生元件效率的關鍵因素。特別是β式結構的葡萄糖類高分子—甲基纖維素，能夠最有效地修飾氧化鋅電子傳輸層的表面，使其能夠分別提升富勒烯系統與非富勒烯系統的有機太陽能電池9.47%與6.34%的原始效率。
另一方面，本研究更利用新穎的生質材料—奈米纖維素製備高透光度、高可撓性且適用於可撓性有機太陽能電池的導電基材。將奈米銀線均勻地分佈在化學改質後的奈米纖維素—TOCN中，製備出的導電基材在透光度跟導電性上可以匹配已商業化的柔性導電基材—PEN/ITO。此外，受益於緊密排列的結構，TOCN導電薄膜跟PEN/ITO相比擁有非常低的熱膨脹係數，以及出色的機械強度與可撓性。最後，以奈米纖維素為導電基材的可撓性太陽能電池被製備出來。利用PM6:Y6作為主動層材料能使元件效率最高達到7.47%。本研究結果為有機太陽能電池的永續發展提供一個新的觀點及方向。

關鍵字

有機太陽能電池 ； 生質高分子 ； 界面修飾 ； 奈米纖維素 ； 柔性導電基材

並列摘要

Due to the advantages of easily processing, high flexibility, and low production cost, organic photovoltaics (OPVs) have drawn lots of attention over the past decade. Besides devoting to enhance the power conversion efficiency (PCE) of OPVs, some scientists have lately shifted the research focus to develop environmentally friendly materials and processing approaches with better economic benefits in order to facilitate the sustainable development of this green energy technique. Among these, incorporating biomaterials into OPVs have received great attention due to the characteristics of generally biodegradable, safe, low-cost and nontoxic of biomaterials.
Therefore, we herein investigated the effectiveness of glucose-based biopolymers as zinc oxide surface modifiers in inverted OPVs by rationally studying chitosan, methyl-cellulose, and dextrin. Owing to the proper side-group and configurational modification, these three biopolymers possess better solution processability and film-formation capability than the pristine cellulose. Besides, their abundant availability in the environment renders them to be easily accessible and more economical as compared to other commonly used polymeric interlayers. Our results reveal the critical structure-performance relationship of these glucose-based biopolymers and its derived OPVs. In particular, the "β-type" glucose-based polymer, methyl-cellulose, was demonstrated as the most efficient modifying interlayer for ZnO ETL, which enables 9.47% and 6.34% enhancement in PCE for the representative fullerene- and NFA-based BHJ systems (PTB7-Th:PC71BM and PBDB-T:ITIC), respectively, as compared to the control devices.
We further demonstrated the fabrication of highly transparent and flexible conductive substrate for flexible OPVs using eco-friendly bio-based material, cellulose nanofibers (CNFs). By uniform coupling with silver nanowire (AgNWs), TEMPO-oxidized cellulose nanofibers (TOCN) conductive substrate exhibited high conductivity as well as high optical transparency, which is comparable with the conventional flexible conductive substrate, polyethylene naphthalate/indium-tin-oxide (PEN/ITO). Moreover, benefiting from its compact nanoscale morphology, TOCNs exhibited excellent mechanical stability and flexibility and a very low coefficient of thermal expansion (CTE) compared to PEN/ITO. Finally, we demonstrated high performance flexible OPVs based on CNFs conductive substrate with the BHJ system of PM6:Y6, which achieved the PCE of 7.47%. Our results provided a new and more sustainable perspective for the fabrication of flexible conductive substrate.

並列關鍵字

OPVs ； biopolymers ； interlayer modification ； CNFs ； flexible conductive substrates

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