本質可拉伸高分子半導體結構設計與場效電晶體元件應用

Structural Design of Semiconducting Polymers with Improved Intrinsic Stretchability and Applications in Field-effect Transistor

林彥丞(Yan-Cheng Lin)

指導教授 ： 陳文章

國立臺灣大學/工學院/化學工程學研究所/博士(2020年)

https://doi.org/10.6342/NTU202004224

摘要

高分子半導體因為其溶液式大規模製程與本質拉伸性之優點而廣為推廣與開發，為了進一步提升其於場效電晶體效能與穿戴式元件應用之可行性，主鏈改質與側鏈改質皆廣泛使用，使其具有更好的固態形貌、結晶排列與本質拉伸性。其中藉由側鏈改質引入氫鍵作用力更是一項備受關注的方法去同時提升電晶體效能與拉伸性能，因此本研究首先系統性地開發具有氫鍵側鏈的高分子半導體(章節二)，將設計帶有聚丙烯酸酰胺側鏈以及辛基十二烷側鏈的異靛藍素噻吩共軛高分子與帶有聚丙酰胺側鏈以及碳矽側鏈的吡咯并吡咯二酮噻吩共軛高分子，藉由引入含有氫鍵的側鏈，高分子固態聚集與結晶性維持皆顯著提升，前者能夠在百分之八十應變下，能夠展現高於0.06 cm2/V-s正交向電洞遷移率，後者在百分之百應變下，能夠展現高於0.1 cm2/V-s正交向電洞遷移率。我們更進一步提出了兩種非對稱構型設計，包含非對稱側鏈設計與三元隨機共聚的主鏈設計以提升高分子半導體之拉伸性能(章節三)，前者包含非對稱側鏈應用於異靛藍素噻吩以及氟噻吩共軛高分子，包含碳矽側鏈、矽氧末端官能化側鏈以及癸基十四烷側鏈，達成100%的應變下維持高達60%正交向電洞遷移率，以及在400圈 60%應變的拉伸循環測試下，維持高達90%的電洞遷移率。後者藉由引入百分之五與十的異靛藍素至吡咯并吡咯二酮噻吩共軛主鏈，後者在百分之百的應變下展現高於0.01 cm2/V-s正交向電洞遷移率。最後我們更開發主鏈雙軸延伸製備近非晶性高分子半導體，以達成高電晶體效能與高拉伸性(章節四)，藉由引入三噻吩烷基側鏈，苯并噻吩共軛高分子可以展現較佳的互叉結構、近非晶性、固態聚集以及快速地鏈─鏈載子躍遷，使其展現高達0.4 cm2/V-s的電洞遷移率，除此之外，更在電晶體效能對應力的維持上，在1000圈60%應變的拉伸循環測試下，展現高達70%電洞遷移率維持，充分展現近非晶性高分子半導體藉由緊密鏈─鏈載子躍遷而達成優越的本質拉伸性。

關鍵字

高分子半導體 ； 場效電晶體 ； 本質拉伸性 ； 氫鍵 ； 非對稱結構設計 ； 雙軸延伸

並列摘要

Semiconducting polymers have been widely developed due to their merits in large-scale processing and stretchability for wearable electronics. In order to improve the performance in field-effect transistor (FET), both backbone engineering and side chain engineering have been extensively applied to achieve better solid-state packing, thin film morphology and intrinsic stretchability with the semiconducting polymers. Among them, side chain with hydrogen bonding interaction opens up a new field to control the conformation and stretchability by strong non-covalent bonds. Thus, a systematic study on the semiconducting polymers with different hydrogen bonding side-chains were conducted (Chapter 2). Intrinsically stretchable isoindigo-bithiophene (PII2T) conjugated polymers with octyldecane (OD) and polyacrylate amide (PAAm) side-chains. And diketopyrrolopyrrole thiophenevinylthiophene (PDPPTVT) conjugated polymers incorporated with carbosilane and polyacrylamide (PAM) side-chains are reported in this work. Stronger molecular aggregation and better crystallinity preservation could be observed. PII2T with 5% PAAm side-chain under a 80% strain showed highly preserved hole mobility (μh) of 0.06 cm2/V-s. And for PDPPTVT with 10% PAM side-chain, the μh can be kept over 0.1 cm2/V-s under a 100% strain.
Next, a novel approach, asymmetric structural design, is proposed in this work to achieve intrinsic stretchability of the semiconducting polymers, including the asymmetric side-chain engineering and random terpolymerization (backbone engineering) (Chapter 3). Asymmetric side-chain engineered PII2T polymers, with carbosilane (Si-C8) side chain, siloxane-terminated (SiO-C8) side chain and decyltetradecane (DT) side chain, were further studied for improved molecular stacking and intrinsic stretchability. Excitingly, isoindigo-difluorobithiophene semiconducting polymers (PII2TF) with asymmetric Si-C8/DT side chains and fluorinated backbone possesses the best orthogonal μh preservation over 60% under 100% strain. For the random terpolymer design, by introducing 5 and 10% isoindigo in diketopyrrolopyrrole-bithiophene backbone (PDPP2T), the μh value reached 0.75 and 1.33 cm2 V-1 s-1, respectively (DPP95 and DPP90). Even with a 100% strain, DPP95 and DPP90 still provided an orthogonal μh over 0.01 cm2 V-1 s-1.
Finally, biaxial-extension of the polymer backbone is adopted to achieve near amorphous polymer with high mobility and intrinsic stretchability (Chapter 4). Benzo[1,2-b:4,5-b']dithiophene (BDT)-based conjugated polymers is equipped with biaxially-extended conjugated side chain of branching alkyl-trithienyl (PBDT-3T). In the morphological analysis, PBDT-3T with a branch-extended side chain presents near amorphous state compared to the parent polymer with linear alkyl-thienyl side-chain. Whereas, PBDT-3T can reach a maximum μh value of 0.4 cm2 V−1 s−1. This can be attributed to the side-chain aggregation in PBDT-3T facilitating side-chains interdigitating and efficient intermittent inter-chain hopping. By utilizing the near amorphous nature, the intrinsic stretchability is enhanced, and PBDT-3T presents a high mechanical tolerance with orthogonal μh retention over 70% after 1000 stretching-releasing cycles with a 60% strain. The results reveal a new design approach for near amorphous polymers with a high charge transporting performance and an excellent intrinsic stretchability.

並列關鍵字

semiconducting polymer ； field-effect transistor ； intrinsic stretchability ； hydrogen-bonding ； asymmetric structural design ； biaxial extention

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