本實驗研究以小分子PTCDI-CnH2n-1為主動層的N型軟性有機薄膜電晶體的穩定性測試，藉由線性移動式平台將元件控制在r = -40、-20、-10 mm及r = +40、+20、+10 mm下由0次撓曲至10000次，並在過程中量測元件的輸出電流特性曲線、轉換特性曲線及元件MISM與MIM架構的電容電壓量測。在實驗分析方面，利用雙束型聚焦離子束儀掃描式電子顯微鏡觀察撓曲5000次後元件的界面是否有剝落的情況，並利用光激發螢光光譜分析PTCDI層撓曲前後的差異。
元件以r = -40、-20、-10 mm及r = +40、+20、+10 mm撓曲由0至10000次的過程中，元件的飽和電流值會隨著撓曲次數的上升而下降，且元件的臨界電壓值也會上升，此外隨著曲率半徑的減少飽和電流值下降與臨界電壓值上升的幅度更為劇烈。在電容電壓量測方面，元件MISM架構的電容值會隨著不斷的撓曲而下降，且介面開始累積電荷的電壓值(On Set Voltage)也隨著上升，此意味半導體層內與介面的缺陷隨著撓曲次數的增加而上升，而MIM架構電容值並不隨撓曲曲率與次數所影響。由掃描式電子顯微鏡拍攝到撓曲過後的元件僅在源極與汲極部份的PTCDI與C-PVP剝離產生空氣隙，此PTCDI與C-PVP剝離產生空氣隙的現象多發生在撓曲的曲率半徑為正值時，且PTCDI的光激發螢光光譜並不隨著撓曲的半徑與次數而改變。

In this thesis, the mechanical stability of N,N’-ditridecyl-3,4,9,10-perylene tetracarboxylic diimide (PTCDI-C13H27)–based organic thin-film transistors (OTFTs) was studied and discussed. Bending OTFTs with radius of curvature of 10, 20, and 40 mm in compressive and tensile states were used to investigate the mechanical stability of devices by a linear-mobile stage. Electrical performance and interface damages of devices were analyzed during the bending operations of 104 times to study the mechanical stability of OTFTs.

The saturated source-drain current (IDS) of OTFTs decreases with increasing the times of bend during the bending operation. In addition, the saturated IDS severely decrease for the device under bending operations with curvature of 10 mm. The capacitance-voltage (C-V) measurement of metal-insulator-semiconductor-metal (MISM) structure decreases with increasing the times of bending operations. In contrast, the on-set voltage of C-V measurement increases with increasing the times of bending operations. These results indicate that the bending operation induces traps or defects in the flexible devices. A focus ion beam scanning electron microscopy (FIB-SEM) was used to observe directly the structure damages in OTFTs. By the FIB-SEM measurement, air-gaps were found at the interface between the insulator and the electrodes of OTFTs. These structure defects lead to the decrease of capacitance of OTFTs and the increase of on-set voltage in C-V measurement. Therefore, the deteriorative interface of OTFTs after mass bending operations leads to the degradation of electrical performances.

[1]. G. Horowitz, “Organic Field-Effect Transistors”, Adv. Mater. 10, 365 (1998)
[2]. J. Collet, O. Tharaud, A. Chapoton, D. Vuillaume, “Low-Voltage, 30 nm channel length, organic transistors with a self-assembled monolayer as gate insulating films”, Appl. Phys. Lett. 76,1941 (2000)
[3]. J. Lee, K. Kim, J.H. Kim, S. Im, “Optimum channel thickness in pentacene-based thin-film transistors”, Appl. Phys. Lett. 69, 4108 (2003)
[4]. P. F. Baude, D. A. Ender, M. A. Haase, T. W. Kelley, D. V. Muyres, ”Pentacene-based radio-frequency identification circuitry”, Appl. Phys. Lett. 82, 3964 (2003)
[5]. D.K. Hwang, C. F-H, J. B. Kim, W. J. P. Jr., B. Kippelen, “Flexible and stable-processed organic field-effect transistors”, Org. Electronic 12, 1108 (2011)
[6]. C. R. Newman, C. D. Frisbie, Demetrio A. da Silva Filho, Jean-Luc Bredas, P. C. Ewbank, Kent R. Mann, “Introduction to Organic Thin Film Transistors and Design of n-Channel Organic Semiconductors”, Chem. Mater. 16, 4436 (2004)
[7]. G. Guillaud, M. A. Sadound, M. Maritrot, “Field-Effect Transistors Based on Intrinsic Molecular Semiconductors”, Chem. Phys. Lett. 167, 503 (1990)
[8]. G. Guillaud, M. A. Sadound, M. Maritrot, “Field-Effect Transistors Based on Intrinsic Molecular Semiconductors”, Chem. Phys. Lett. 167, 503 (1990)
[9]. J. Kastner, J. Paloheimo, H. Kuzmany, “Conduction mechanisms in doped thin film of C60 and C60/70”, Science Metals 55 , 3185 (1993)
[10]. R. C. Haddon, A. S. Perel, R. C. Morris, T. T. M. Palstra, A. F. Herbard, R. M. Fleming, “C-60 Thin-Film Transistors”, Appl. Phys. Lett. 67, 121 (1995)
[11]. S. Kobaysashi, T. Takenobu, S. Mori, A. Fujiwara, Y. Iwasa, “C 60 thin-film transistors with high field-effect mobility, fabricated by molecular beam deposition”, Adv. Mater. 4 , 371 (2003)
[12]. J. G. Laquindanum, H. E. Katz, A. Dodabalapur, A. J. Loninger, “n-channel organic transistor materials based on naphthalene frameworks”, J. Am. Chem. Soc. 118, 11331 (1996) A. R. Brown, D. M. de Leeuw, E. J. Lous, E. E. Havingga, “Organic N-Type Field-Effect Transistor”, Synth. Met. 66, 257 (1994)
[13]. J. R. Ostrick, A. Dondabalapur, L. Torsi, A. J. Loninger, E. W. Lwol, T. M. Miller, “Conductivity-type anisotropy in molecular solids”, J. Appl. Phys. 81, 6804 (1997)
[14]. S. Kobaysashi, T. Takenobu, S. Mori, A. Fujiwara, Y. Iwasa, “C 60 thin-film transistors with high field-effect mobility, fabricated by molecular beam deposition”, Adv. Mater. 4 , 371 (2003)
[15]. R. J. Chesterfield, J. C. McKeen, C. R. Newman, P. C. Ewbank, D. A. da S. Filho, J.-L. Brédas, L. L. Miller, K. R. Mann, C. D. Frisbie, “Organic thin film transistors based on N-alkyl perylene diimides: Charge transport kinetics as a function of gate voltage and temperature”, J. Phys. Chem. B. 108, 19281 (2004)
[16]. S. Tatermichi, M. Ichikawa, T. Koyama, Y. Taniguchi, “High mobility n-type thin-film transistors based on N,N’-ditridecyl perylene diimide with thermal treatments”, Appl. Phys. Lett. 89, 112108 (2006)
[17]. J. H. Oh, S. Liu, Z. Bao, R. Schmidt, F. Wurthner, “Air-stable n-channel organic thin-film transistors with high field-effect mobility based on N,N’-bis(heptafluorobutyl) 3,4:9,10-perylene diimide”, Appl. Phys. Lett. 91, 212107 (2007)
[18]. S. Hutter, M. Sommer, M. Thelakkat, ”n-type organic field effect transistors from perylene bisimide block copolymers and homopolymers”, Appl. Phys. Lett. 92, 093302 (2008).
[19]. Z. Wei, H. Xi, H. Dong, L. Wang, W. Xu, W. Hu, D. Zhu, “Blending induced stack-ordering and performance improvement in a solution-processed n-type organic field-effect transistor ” J. Mater. Chem. 20, 1203 (2009)
[20]. H. G. Jeon, et al. , “Thermal treatment effects on N-alkyl perylene diimide thin-film transistors with different alkyl chain”, J. Appl. Phys. 108 , 124512 (2010)
[21]. 林益生，以烷基駢苯衍生物作為主動層之有機薄膜電晶體，國立成功大學碩士論文 (2008)