新穎共軛高分子之合成和形態鑑定及其於薄膜電晶體與太陽能電池元件應用

Syntheses, Morphology, and Properties of New Conjugated Polymers for High Performance Field Effect Transistors and Solar Cell Applications

林翔偉(Hsiang-Wei Lin)

指導教授 ： 陳文章

國立臺灣大學/工學院/高分子科學與工程學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.00563

摘要

高度結晶性共軛高分子由於具有高度順向性的排列而使其於薄膜電晶體與光伏打電池上的應用具有極好的元件表現，故近年來這方面的研究相當受到囑目。為了達到良好的元件特性，必須設計及合成出具有高電荷遷移率、規整與可調控的形態表現以及適當的分子能階的共軛高分子。因此，此碩士論文的目標在於利用具有共軛側鏈的聚噻吩以及具有強分子間作用力的硒吩單元來設計一系列高效能的共軛高分子。茲詳細介紹如下:

1. 以二維排列噻吩為基礎之新穎共軛高分子應用於有機薄膜電晶體與光伏打電池(第二章)
以二維排列噻吩(4T)為基礎，搭配不同之單元(T、Se、2T、2Se與TT)利用微波反應器合成出一系列之共聚高分子以及合成出其均聚物(P4T)。其高分子結構對於分子能階、電荷遷移率及光伏打電池特性是具有高度相關性的。其中，P4TTT由於具有高度的結晶性排列而具有最高的電洞遷移率高達0.396 cm2 V-1 s-1¬，同時也有高的電流開關比為7.45×105。對於共軛高分子混摻碳七十衍生物做為太陽能電池主動層的系統，P4TSe展現了最高的光電轉換效率達2.60%。綜合以上的結果顯示以二維排列噻吩(4T)系統發展之共軛高分子是具有增強電荷傳遞的能力，使其將是有機光電元件應用上的明日之星。

2.以硒吩建構之新穎施體/受體共軛高分子應用於高效能之薄膜電晶體、非揮發性記憶體及太陽能電池元件(第三章)
以硒吩(Se)及具有雙吡咯(DPP)官能基的單元利用微波反應器進行新材料PSeDPP之共軛高分子聚合。所獲得之高分子於退火後能夠形成較完整的層狀排列及π–π間的堆疊。此外，其電洞及電子的遷移率可以分別高達1.62 cm2 V-1 s-1¬及0.14 cm2 V-1 s-1，具有大量儲存電荷的能力，有利於應用於記憶體元件上。另一方面，當使用一比二的重量比混摻PSeDPP/PCBM並添加3vt%的添加劑DIO時，可以於太陽能電池元件上得到轉換效率1.64%。由以上的結果可知，多功能性的共軛高分子材料PSeDPP於可撓式有機元件的應用上是深具潛力的。

關鍵字

共軛高分子 ； 薄膜電晶體 ； 太陽能電池

並列摘要

Conjugated copolymers with well-ordered packing have attracted significant scientific interest recently due to their potential applications for high performance field-effect transistor and photovoltaic cells. In this thesis, we developed two new series of conjugated polymers to meet the above applications: (1) two-dimensional conjugated polythiophene with conjugated side chains; (2) selenophene based donor-acceptor conjugated polymers. The details of explorations are summarized as below:

1. Novel Two-Dimensional Quarterthiophene-Based Conjugated Polymers for Organic Field Effect Transistors and Photovoltaic Cells (Chapter 2): A series of new 4T-based polymers, including homopolymer poly(5,5’’’-di- (2-ethylhexyl)[2,3’;5’,2’’;4’’,2’’’] quarterthiophene) (P4T) and their copolymers P4TT, P4TSe, P4T2T, P4T2Se and P4TTT have been synthesized by Stille coupling reactions under microwave heating. The effects of their chemical structures on the electronic energy level, charge transport and photovoltaic properties were explored systematically. Among these copolymers, the field-effect transistor based on P4TTT showed the highest hole mobility of up to 0.396 cm2 V-1 s-1 due to its highly crystalline packing structure, and exhibited a high on/off ratio of 7.45×105, simultaneously. The performances of bulk heterojunction polymer solar cells based on the blends of these 4T-based polymers and 1-(3-methoxycarbonyl)-pyropyl-1-phenyl[6,6]C-71 (PC71BM) were also characterized. P4TSe/PC71BM based photovoltaic device showed the highest power conversion efficiency (PCE) of 2.60% under AM 1.5 illumination (100 mW/cm2). The above results exhibited that two-dimensional 4T-based conjugated copolymers could enhance the charge transport characteristics and emerge as a promising candidate for organic optoelectronic devices.

2. New Selenophene Donor-Acceptor Conjugated Polymer for High Performance Ambipolar Field Effect Transistor, and Solar Cell Applications (Chapter 3): A new conjugated copolymer PSeDPP from 2,5-bis-(trimethylstannyl)-selenophene(Se) and 3,6-bis-(5-bromo-thiophene-2-yl)-2,5-bis-(2-hexyldecyl)-2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione(DPP) was synthesized by Stille coupling reaction under microwave heating. The obtained polymer could form highly ordered lamella structure and π–π stacking after thermal annealing. Besides, the charge transporting characteristics of PSeDPP exhibited the relatively hole and electron mobility of up to 1.62 and 0.14 cm2 V-1s-1, respectively, which could store a large amount of charges to the memory device applications. On the other hand, PSeDPP based photovoltaic solar cells exhibited the best PCE of 1.64% with the blending weight ratio 1:2 for PSeDPP/PC71BM and 3vt% of 1,8-diiodooctane. The above results suggested that PSeDPP had potential applications for flexible electronics.

並列關鍵字

Conjugated Polymer ； Thin-Film Transistors ； Photovoltaic Cells

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