本研究聚焦於分析雙極性有機薄膜電晶體的動態電特性與在低溫環境下的磁效應。第一部份，探討雙極性有機薄膜電晶體在時域變化下的電性表現，藉由調整閘極電壓的延遲時間，改變電壓的掃描速度，並配合雙載子復合釋放模型來分析電荷載子在元件通道內的行為，發現電壓掃描速度越快會使載子釋放電壓產生延遲現象。接著，利用調整反向閘極偏壓與汲極電壓的大小，發現電荷載子的注入與解離行為具有電場相依之特性，幫助我們釐清電場在雙載子復合與釋放行為中扮演的角色。最後，藉由動態量測元件的通道電流，發現電子與電洞的交互作用，符合雙載子復合釋放模型對載子在通道內的行為描述。第二部分，經由元件在不同環境溫度下的電特性表現，發現影響雙載子解離行為是一電場輔助的熱活化機制。接著加入磁場作為干擾因子，得到元件在不同操作模式下有不同的磁效應，其原因可能是外加磁場會降低三重態電子電洞對與載子發生碰撞的比例，造成正負磁阻的差異。因此考慮電子自旋後的雙載子復合釋放模型更能完善地描述有機薄膜電晶體的雙載子傳輸機制。

This study analyzed the dynamic electrical properties and the effect of external magnetic field on the electrical characteristics of pentacene-based ambipolar organic thin-film transistors (pen-AmOTFTs). In the first part, the transfer characteristics of ambipolar OTFTs were subjected to time-domain analysis. To explore the effects of dual-carrier recombination and release (DCRR) on the electrical characteristics of pen-AmOTFTs, the sweep speed of electrical characteristic measurement was adjusted by changing the sweep delay of gate voltage (VG). An increase in turn-on voltage (Von) was obtained with the sweep speed of voltage. This study proposed that the mechanism of the injection and dissociation of carriers was dependent on electric field in pen-AmOTFTs, thereby clarifying the role of electric field in DCRR process. Dynamic measurements confirmed that electron-hole interactions occurred in an active channel and produced V-shape transfer curves. In the second part, the behavior of dual-carrier dissociation was an electric field-assisted thermal-activated procedure. When pen-AmOTFTs were operated in the presence of an external magnetic field, positive and negative magnetic resistance (MR) behaviors were observed in n- and p-channel operations, respectively. The difference between n- and p-channel operations under the application of the external magnetic field was further discussed. In summary, the mechanism of carrier transport in pen-AmOTFTs could be well described by using the DCRR model and considering spintronics.

[1] H. Koezuka, A. Tsumura, T. Ando, Field-effect transistor with polythiophene thin film, Synthetic Metals, 18 (1987) 699-704.
[2] G. Horowitz, Organic field‐effect transistors, Advanced materials, 10 (1998) 365-377.
[3] L.-L. Chua, J. Zaumseil, J.-F. Chang, E.C.-W. Ou, P.K.-H. Ho, H. Sirringhaus, R.H. Friend, General observation of n-type field-effect behaviour in organic semiconductors, Nature, 434 (2005) 194.
[4] J. Veres, S. Ogier, G. Lloyd, D. De Leeuw, Gate insulators in organic field-effect transistors, Chemistry of materials, 16 (2004) 4543-4555.
[5] C. Wang, H. Dong, W. Hu, Y. Liu, D. Zhu, Semiconducting π-conjugated systems in field-effect transistors: a material odyssey of organic electronics, Chemical Reviews, 112 (2011) 2208-2267.
[6] D. Khim, A. Luzio, G.E. Bonacchini, G. Pace, M.J. Lee, Y.Y. Noh, M. Caironi, Uniaxial Alignment of Conjugated Polymer Films for High‐Performance Organic Field‐Effect Transistors, Advanced Materials, 30 (2018) 1705463.
[7] S. Günes, H. Neugebauer, N.S. Sariciftci, Conjugated polymer-based organic solar cells, Chemical reviews, 107 (2007) 1324-1338.
[8] Y.-J. Cheng, S.-H. Yang, C.-S. Hsu, Synthesis of conjugated polymers for organic solar cell applications, Chemical reviews, 109 (2009) 5868-5923.
[9] M. Liu, M.B. Johnston, H.J. Snaith, Efficient planar heterojunction perovskite solar cells by vapour deposition, Nature, 501 (2013) 395.
[10] N.J. Jeon, H. Na, E.H. Jung, T.-Y. Yang, Y.G. Lee, G. Kim, H.-W. Shin, S.I. Seok, J. Lee, J. Seo, A fluorene-terminated hole-transporting material for highly efficient and stable perovskite solar cells, Nature Energy, 3 (2018) 682.
[11] A.P. Kulkarni, C.J. Tonzola, A. Babel, S.A. Jenekhe, Electron transport materials for organic light-emitting diodes, Chemistry of materials, 16 (2004) 4556-4573.
[12] S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K. Leo, White organic light-emitting diodes with fluorescent tube efficiency, Nature, 459 (2009) 234.
[13] T.-L. Wu, M.-J. Huang, C.-C. Lin, P.-Y. Huang, T.-Y. Chou, R.-W. Chen-Cheng, H.-W. Lin, R.-S. Liu, C.-H. Cheng, Diboron compound-based organic light-emitting diodes with high efficiency and reduced efficiency roll-off, Nature Photonics, 12 (2018) 235.
[14] H. Sirringhaus, Device physics of solution‐processed organic field‐effect transistors, Advanced Materials, 17 (2005) 2411-2425.
[15] S.C. Mannsfeld, B.C. Tee, R.M. Stoltenberg, C.V.H. Chen, S. Barman, B.V. Muir, A.N. Sokolov, C. Reese, Z. Bao, Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers, Nature materials, 9 (2010) 859.
[16] Y. Zhao, X. Zhao, M. Roders, A. Gumyusenge, A.L. Ayzner, J. Mei, Melt‐Processing of Complementary Semiconducting Polymer Blends for High Performance Organic Transistors, Advanced Materials, 29 (2017) 1605056.
[17] A. Troisi, Charge transport in high mobility molecular semiconductors: classical models and new theories, Chemical Society Reviews, 40 (2011) 2347-2358.
[18] T. Lei, J.-Y. Wang, J. Pei, Design, synthesis, and structure–property relationships of isoindigo-based conjugated polymers, Accounts of chemical research, 47 (2014) 1117-1126.
[19] R. Schmechel, M. Ahles, H. von Seggern, A pentacene ambipolar transistor: Experiment and theory, Journal of applied physics, 98 (2005) 084511.
[20] L.-Y. Chiu, H.-L. Cheng, W.-Y. Chou, F.-C. Tang, The influence of dual-carrier recombination and release on electrical characteristics of pentacene-based ambipolar transistors, Applied Physics Letters, 103 (2013) 207_201.
[21] T.-J. Ho, H.-L. Cheng, L.-Y. Chiu, W.-Y. Chou, F.-C. Tang, Temperature-dependent ambipolar electrical characteristics of pentacene-based thin-film transistors: The impact of opposite-sign charge carriers, Organic Electronics, 25 (2015) 74-78.
[22] Keithley 4200-SCS user manual, Keithley Instruments Inc, (2013)
[23] Device Characterization with the Keithley Model 4200-SCS Characterization System, Keithley Instruments Inc, (2013)
[24] E. Meijer, D. De Leeuw, S. Setayesh, E. Van Veenendaal, B.-H. Huisman, P. Blom, J. Hummelen, U. Scherf, T. Klapwijk, Solution-processed ambipolar organic field-effect transistors and inverters, Nature materials, 2 (2003) 678.
[25] J.C. Bijleveld, A.P. Zoombelt, S.G. Mathijssen, M.M. Wienk, M. Turbiez, D.M. de Leeuw, R.A. Janssen, Poly (diketopyrrolopyrrole− terthiophene) for Ambipolar Logic and Photovoltaics, Journal of the American Chemical Society, 131 (2009) 16616-16617.
[26] Z. Chen, M.J. Lee, R. Shahid Ashraf, Y. Gu, S. Albert‐Seifried, M. Meedom Nielsen, B. Schroeder, T.D. Anthopoulos, M. Heeney, I. McCulloch, High‐performance ambipolar diketopyrrolopyrrole‐thieno [3, 2‐b] thiophene copolymer field‐effect transistors with balanced hole and electron mobilities, Advanced materials, 24 (2012) 647-652.
[27] T.-J. Ho, C.-W. Hung, Y.-W. Wang, W.-Y. Chou, F.-C. Tang, H.-L. Cheng, Temperature effects on the electrical properties of ambipolar organic complementary-like inverters, Organic Electronics, 72 (2019) 25-29.
[28] A. Petersen, A. Ojala, T. Kirchartz, T.A. Wagner, F. Würthner, U. Rau, Field-dependent exciton dissociation in organic heterojunction solar cells, Physical Review B, 85 (2012) 245208.
[29] A. Maliakal, K. Raghavachari, H. Katz, E. Chandross, T. Siegrist, Photochemical stability of pentacene and a substituted pentacene in solution and in thin films, Chemistry of materials, 16 (2004) 4980-4986.
[30] Z. Xiong, D. Wu, Z.V. Vardeny, J. Shi, Giant magnetoresistance in organic spin-valves, Nature, 427 (2004) 821.
[31] Ö. Mermer, G. Veeraraghavan, T. Francis, Y. Sheng, D. Nguyen, M. Wohlgenannt, A. Köhler, M.K. Al-Suti, M. Khan, Large magnetoresistance in nonmagnetic π-conjugated semiconductor thin film devices, Physical Review B, 72 (2005) 205202.
[32] T. Reichert, T.P. Saragi, Photoinduced magnetoresistance in organic field-effect transistors, Applied Physics Letters, 98 (2011) 29.
[33] S.-T. Pham, Y. Kawasugi, H. Tada, Organic magnetoresistance in ambipolar field-effect transistors, Applied Physics Letters, 103 (2013) 183_181.
[34] S. Wolf, D. Awschalom, R. Buhrman, J. Daughton, S. Von Molnar, M. Roukes, A.Y. Chtchelkanova, D. Treger, Spintronics: a spin-based electronics vision for the future, science, 294 (2001) 1488-1495.
[35] A. Monkman, H. Burrows, L. Hartwell, L. Horsburgh, I. Hamblett, S. Navaratnam, Triplet energies of π-conjugated polymers, Physical Review Letters, 86 (2001) 1358.
[36] A. Köhler, D. Beljonne, The singlet–triplet exchange energy in conjugated polymers, Advanced Functional Materials, 14 (2004) 11-18.
[37] A. Kadashchuk, A. Vakhnin, I. Blonski, D. Beljonne, Z. Shuai, J. Bredas, V. Arkhipov, P. Heremans, E. Emelianova, H. Bässler, Singlet-triplet splitting of geminate electron-hole pairs in conjugated polymers, Physical review letters, 93 (2004) 066803.
[38] B. Hu, L. Yan, M. Shao, Magnetic‐field effects in organic semiconducting materials and devices, Advanced Materials, 21 (2009) 1500-1516.
[39] N. Rolfe, M. Heeney, P. Wyatt, A. Drew, T. Kreouzis, W. Gillin, Elucidating the role of hyperfine interactions on organic magnetoresistance using deuterated aluminium tris (8-hydroxyquinoline), Physical Review B, 80 (2009) 241201.
[40] J. Bai, P. Chen, Y. Lei, Y. Zhang, Q. Zhang, Z. Xiong, F. Li, Studying singlet fission and triplet fusion by magneto-electroluminescence method in singlet–triplet energy-resonant organic light-emitting diodes, Organic Electronics, 15 (2014) 169-174.