臺灣博碩士論文加值系統

　　電晶體是基本且重要的基本電子元件，若中間半導體材質為有機導電高分子則可使電晶體擁有可撓曲性(flexible)，並具造價便宜、製程簡單等特質。這幾年有機場效電晶體受到許多注目與研究，聚噻吩P3HT在共軛高分子中有不錯的載子遷移率，大約為0.01-0.2 cm2/Vs；另一P3HT之衍生物PBTTT，由於稠環的修飾，其載子遷移率提升至0.6cm2/Vs。我們利用分子動力模擬，由結構的觀點探究此二系統內影響載子遷移的重要因素。
　　本篇使用分子動力學模擬計算，由結構之觀點探究此二高分子其載子遷移率差異因素為何。模擬結果顯示，此類高分子主鏈上噻吩環面間及側基烷鏈方向有較強的非鍵結作用力，在此二維度上容易出現自組裝的行為，主鏈間自組裝能力又優於側鏈間之自組裝能力，軌跡分析主鏈間自組裝達平衡位置之速率約為側基自組裝之速率的10倍。計算所得PBTTT與P3HT之結構特徵，例如層間距離、共軛環間距離、環面傾斜角，都與XRD光譜圖主要吸收峰或相關實驗量測值相符，確認模擬結構之可信度，並解釋P3HT熱處理與副結構消失之關聯性。高分子側基烷鏈雖不具電子傳導之能力，卻透過自組裝排列之優劣，影響另二導電維度高分子主鏈上與主鏈間環面之堆排，而造成不同載子遷移率之影響。PBTTT高分子側基間插合堆排能力佳，使結構於規整區塊中能維持其剛硬性，主鏈上之噻吩環扭轉角維持在±10°左右，有較好的共平面性，且環面間π堆疊距離約為3.6Å，有利載子傳輸之進行。反觀P3HT間插合堆排能力差，迫使主鏈呈現波浪狀，主鏈上之噻吩環扭轉角偏離值約為±30°，共平面性較差，環面間π堆疊距離約為3.7Å，與PBTTT高分子比較，可解釋P3HT高分子較PBTTT不利載子傳輸之進行。

Polymer semiconductors based on thienothiophene copolymers such as poly(3-hexylthiophene) (P3HT), and poly [2,5-bis(3-alkylthiophen- 2-yl)thieno(3,2-b)thiophene] (PBTTT) has been the target of many recent investigations, because of their great potential use as a viable alternative to amorphous silicon in a range of thin-film transistor devices. In recent work the polymer series PBTTT-Cn was reported to exhibit field-effect mobility in the range of 0.2– 1 cm2 / Vs. This result has given rise to considerable interest in PBTTT-Cn because these mobilities are greater than those seen in P3HT of being 0.01- 0.2 cm2 /Vs. Our objective in investigating the atomic and electronic structure of the materials is to gain insight into the reasons for the difference in mobility of these materials.
We use molecular dynamics simulations to study the electronic and structural properties of P3HT and PBTTT in dilute and concentrated systems. The results show that non-bonding interactions in the alkyl side chain and π-π stacking directions induce polymer regio-regular assembly. Moreover, we found that inter-polymer-chain π-π stacking assembles 1 order faster than the side chain interdigitation. The characteristic structures in the order domain are in good agreement with XRD experiment and NEXAFS measurement. The trajectories show that although the carrier will not transport along the side chain direction, the side chain affects the structures of other two directions of π-π stacking and main chain, charge-carrier mobility,
The side chain of PBTTT can fully interdigitate ordered through assembly process, which provides the stable alignment of main chain and closed π-π stacking of 3.6Å. Therefore results show that PBTTT has more rigid main chain structure and the torsion angles between thiophene rings are distributed around 180° ± 10°. Conversely, the partial side chain interdigitation in P3HT results in flexible main chain alignment with torsion distribution around 180° ± 35°and π-π stacking of 3.7Å. These structural properties of molecular orientations provide a new insight into the anisotropic electrical properties and to explain the carrier transport difference in the structure of organic semiconductor thin films.

第一章 緒論
1.1 導電高分子的演進與發展
1.2 軟性電子材料之場效電晶體的應用
1.3 聚噻吩及其衍生物之載子遷移率
1.3.1 分子量之於載子遷移率
1.3.2 結構特性
第二章　研究動機、目的及方法
2.1　研究動機
2.2　研究目的
2.3　研究方法
2.3.1　分子動力學模擬
2.3.2　分子力場
2.3.3周期性邊界條件與最近鏡像
2.4　模擬系統與流程
第三章　結果討論
3.1　高分子自組裝
3.1.1　π-π堆疊與側基疏水插合能力之比較
3.1.2　長程側基插合能力
3.1.3　引導側基插合能力
3.2　P3HT之規整區塊結構
3.2.1　熱處理
3.2.2　側基插合與扭轉角
3.3　模擬數據與實驗數據比對
第四章　結論與展望
第五章　參考文獻
第六章　附錄

1. Angeli, A., A. Gazz. Chim. Ital. 1916, 46, 279.
2. Chiang, C. K.; Druy, M. A.; Gau, S. C.; Heeger, A. J.; Louis, E. J.; MacDiarmid, A. G.; Park, Y. W.; Shirakawa, H., J. Am. Chem. SOC. 1978, 100, 1013.
3. Kelley, T. W.; Boardman, L. D.; Dunbar, T. D.; Muyres, D. V.; Pellerite, M. J.; Smith, T. P., J. Phys. Chem. B 2003, 107. 5877.
4. Kline, R. J.; McGehee, M. D.; Toney, M. F., Nat. Mater. 2006, 5, 222.
5. Street, R. A.; Northrup, J. E.; Salleo, A., Phy. Rev. B 2005, 71, 165202.
6. Sirringhaus, H.; Tessler, N.; Friend, R., Science 1998, 280, 1741.
7. Wang, G.; Swensen, J.; Moses, D.; Heeger, A. J., J. Appl. Phys. 2003, 93, 6137.
8. McCulloch, I.; Heeney, M.; Bailey, C.; Genevicius, K.; Macdonald, I.; Shkunov, M.; Sparrowe, D.; Tierney, S.; Wagner, R.; Zhang, W.; Chabinyc, M. L.; Kline, R. J.; McGehee, M. D.; Toney, M. F., Nat. Mater. 2006, 5, 328.
9. Northrup, J. E., Phy. Rev. B 2007, 76, 165202.
10. Salleo, A., materials today 2007, 10,
11. Chabinyc, M. L.; Toney, M. F.; Kline, R. J.; McCulloch, I.; Heeney, M., J. Am. Chem. Soc. 2007, 129, 3226.
12. Jen, K. Y.; Oboodi, R.; Elsenbaumer, R. L., Sci. Eng. 1986, 53.
13. McCullough, R. D.; Lowe, R. D., J. Chem. Soc. 1992, 70.
14. Kline, R. J.; McGehee, M. D.; Kadnikova, E. N.; Liu, J.; Frchet, J. M. J.; Toney, M. F., Macromolecules 2005, 38, 3312.
15. Sirringhaus, H.; Brown, P. J.; Friend, R. H.; Nielsen, M. M.; Bechgaard, K.; Langeveld-Voss, B. M. W.; Spiering, A. J. H.; Janssen, R. A. J.; Meijer, E. W.; Herwig, P.; Leeuw, D. M. d., Nature 1999, 401, 685.
16. Kline, R. J.; DeLongchamp, D. M.; Fischer, D. A.; Lin, E. K.; Heeney, M.; McCulloch, I.; Toney, M. F., Appl. Phys. Lett 2007, 90, 062117.
17. Lucas, L. A.; DeLongchamp, D. M.; Vogel, B. M.; Lin, E. K.; Fasolka, M. J.; Fischer, D. A., Appl. Phys. Lett 2007, 90, 012112.
18. Joshi, S.; Grigorian, S.; Pietsch, U., Phys. stat. sol. 2008, 3, 488.
19. Sun, H., Macromolecules 1995, 28, 701.
20. Mayo, S. L.; Olafson, B. D.; Goddard, W. A., J. Phys. Chem. 1990, 94, 8897.
21.Anderson, H. C., J. Chem. Phys. 1980, 72, 2384.
22.DeLongchamp, D. M.; Kline, R. J.; Eric K. Lin, D. A. F.; Richter, L. J.; Lucas, L. A.; Heeney, M.; McCulloch, I.; Northrup, J. E., Adv. Mater., 2007, 19, 833.