臺灣博碩士論文加值系統

有機光電元件中，藉由非侷域化電子雲的重疊進行電荷的傳輸，因此共軛分子堆疊排列的方式被認為是影響載子傳輸特性的重要因素。在本研究中，我們藉由觀察基板對於並五苯的堆疊影響，探討基板和分子作用的行為。
並五苯是典型小分子有機光電材料，擁有許多良好的物理特質，如能形成良好排列的薄膜、遷移距離較長等。在介電材料上，如二氧化矽，並五苯分子以長軸站立的方式排列，適合平行基板的電荷傳遞，因此一般被使用在有機薄膜電晶體的傳輸層；我們在石墨烯／銅箔的基板上，藉由X光繞射、拉曼光譜等分析，發現並五苯分子以面向基板的方式堆疊，此傳遞方向對於以垂直傳遞電荷的元件來說極有助益。另外，我們以偏極化拉曼光譜，觀測以石墨烯為基底，其排列對於上方分子排列的可能影響。
藉由了解分子與基板作用力的不同，對於有機分子薄膜成長的行為，進而能有更多的調控。

Pentacene is one of the oligomer conducting materials used in small molecule organic optoelectronic devices, such as organic light-emitting diode (OLED), organic field-effect transistor (OFET), and photovoltaic cell (PV). However, the effects of substrate dominate the molecular orientation of the thin film. For instance, pentacene thin films are deposited on gate dielectrics, e.g., SiO2, where a substrate induced phase of pentacene molecules is in the appropriate charge transport direction for an OFET. Therefore, the effects of substrate can play a dominant role in orientation and thus influence the performance of the device.
In this work, by using chemical vapor deposition (CVD) graphene as a template, we investigate the crystal phases, morphology, surface energy, and electrical properties of pentacene thin films with varying thickness. The thin films have been characterized by X-ray diffraction (XRD) to resolve the crystal phases and tilt angle (θtilt). Atomic force microscope is employed to observe the surface. Surface energy of the films are estimated through contact angle. And polarized micro-Raman spectroscopy is to identify the molecular orientation dependence with graphene. Eventually, the electrical property of different molecular orientation is also examined.
These results provide a direct evidence that pentacene orients in the perpendicular direction with respect to the glass, whereas it is parallel on graphene/Cu substrate. The effects of strong molecule−substrate interaction such as standing-up and lying-down molecules on different substrates have also been discussed based on the fact that they enable to determine the charge transport and further influence the performance of OPV devices.

致謝 I
中文摘要 II
Abstract III
Contents IV
List of Figures VI
List of Tables XI
Chapter 1 Introduction 1
1.1 Basic properties of conjugated molecule system 1
1.1.1 Organic semiconductors 1
1.1.2 Graphene 4
1.2 Growth modes of thin films 7
1.3 Aim of this thesis 11
Reference 12
Chapter 2 Review of related literature 14
2.1 Conventional methods to control molecular orientation 14
2.2 Graphene as a template 18
Reference 22
Chapter 3 Experiment and Instrument 24
3.1 Sample preparstion 24
3.2 Instrument 26
3.2.1 Thermal vapor evaporator 26
3.2.2 Raman scattering and measurement 27
3.2.3 X-ray diffraction (XRD) 31
3.2.4 Atomic force microscope (AFM) 32
3.2.5 Surface energy measurement 34
3.2.6 Electrical property measurement 37
Reference 39
Chapter 4 Characterization of pentacene thin films on graphene and SiO2 41
4.1 Crystal orientation of pentacene thin films 41
4.2 Growth mode of pentacene thin films 45
4.3 Molecular orientation of pentacene thin films 48
4.4 Electrical property of molecular orientation of pentacene thin films 53
Reference 55
Chapter 5 Future vision 57

Ch1
1McNaught, A. D. & Wilkinson, A. I{UPAC}. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). (WileyBlackwell; 2nd Revised edition edition).
2Jackson, T. N. in SID seminar notes (2004).
3Smith, M. B. & March, J. March''s Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. (Wiley, 2007).
4Wikipedia contributors. Conjugated system, <http://en.wikipedia.org/w/index.php?title=Conjugated_system&oldid=539672569> (
5Akamatu, H., Inokuchi, H. & Matsunaga, Y. ELECTRICAL CONDUCTIVITY OF THE PERYLENE-BROMINE COMPLEX. Nature 173, 168-169, doi:10.1038/173168a0 (1954).
6Kolb, D. Pentacene-based organic transistors Doctoral Dissertation thesis, School of Engineering, University of Durham, (2005).
7Brutting, W. Physics of Organic Semiconductors. (Wiley, 2005).
8Gundlach, D. J., Lin, Y. Y., Jackson, T. N., Nelson, S. F. & Schlom, D. G. Pentacene organic thin-film transistors - Molecular ordering and mobility. IEEE Electron Device Lett. 18, 87-89, doi:10.1109/55.556089 (1997).
9Klauk, H., Gundlach, D. J., Nichols, J. A. & Jackson, T. N. Pentacene organic thin-film transistors for circuit and display applications. IEEE Trans. Electron Devices 46, 1258-1263, doi:10.1109/16.766895 (1999).
10Chou, W. Y. & Cheng, H. L. An Orientation-Controlled Pentacene Film Aligned by Photoaligned Polyimide for Organic Thin-Film Transistor Applications. Advanced Functional Materials 14, 811-815, doi:10.1002/adfm.200305047 (2004).
11Huang, M. et al. Phonon softening and crystallographic orientation of strained graphene studied by Raman spectroscopy. Proceedings of the National Academy of Sciences of the United States of America 106, 7304-7308, doi:10.1073/pnas.0811754106 (2009).
12Geim, A. K. & Novoselov, K. S. The rise of graphene. Nat. Mater. 6, 183-191, doi:10.1038/nmat1849 (2007).
13Ferrari, A. C. et al. Raman Spectrum of Graphene and Graphene Layers. Physical Review Letters 97, doi:10.1103/PhysRevLett.97.187401 (2006).
14Ferrari, A. C. & Basko, D. M. Raman spectroscopy as a versatile tool for studying the properties of graphene. Nat. Nanotechnol. 8, 235-246, doi:10.1038/nnano.2013.46 (2013).
15Sahoo, S., Palai, R. & Katiyar, R. S. Polarized Raman scattering in monolayer, bilayer, and suspended bilayer graphene. Journal of Applied Physics 110, 044320, doi:10.1063/1.3627154 (2011).
16Gregor, H. & Christian, T. Nucleation and growth of thin films of rod-like conjugated molecules. Journal of Physics: Condensed Matter 25, 143202 (2013).
17Ruiz, R. et al. Pentacene Thin Film Growth. Chemistry of Materials 16, 4497-4508, doi:10.1021/cm049563q (2004).
18Nickel, B. et al. Pentacene devices: Molecular structure, charge transport and photo response. physica status solidi (a) 205, 526-533, doi:10.1002/pssa.200723372 (2008).
19Cheng, H. L., Mai, Y. S., Chou, W. Y., Chang, L. R. & Liang, X. W. Thickness-Dependent Structural Evolutions and Growth Models in Relation to Carrier Transport Properties in Polycrystalline Pentacene Thin Films. Advanced Functional Materials 17, 3639-3649, doi:10.1002/adfm.200700207 (2007).
20Mai, Y.-S. Early Stages of Pentacene Thin Film Growth on Dielectric Doctoral Dissrtation thesis, National Cheng Kung University, (2007).
21Lukas, S., Sohnchen, S., Witte, G. & Woll, C. Epitaxial Growth of Pentacene Films on Metal Surfaces. ChemPhysChem 5, 266-270, doi:10.1002/cphc.200300892 (2004).
Ch2
1Suemori, K. et al. Influence of fine roughness of insulator surface on threshold voltage stability of organic field-effect transistors. Applied Physics Letters 93, 033308, doi:10.1063/1.2957987 (2008).
2Jo, P. S. et al. Controlled Topology of Block Copolymer Gate Insulators by Selective Etching of Cylindrical Microdomains in Pentacene Organic Thin Film Transistors. Advanced Functional Materials 18, 1202-1211, doi:10.1002/adfm.200701034 (2008).
3Shao, W., Dong, H., Jiang, L. & Hu, W. Morphology control for high performance organic thin film transistors. Chemical Science 2, 590, doi:10.1039/c0sc00502a (2011).
4Sun, X., Di, C.-a. & Liu, Y. Engineering of the dielectric–semiconductor interface in organic field-effect transistors. Journal of Materials Chemistry 20, 2599, doi:10.1039/b921449f (2010).
5Yang, S. Y., Shin, K. & Park, C. E. The Effect of Gate-Dielectric Surface Energy on Pentacene Morphology and Organic Field-Effect Transistor Characteristics. Advanced Functional Materials 15, 1806-1814, doi:10.1002/adfm.200400486 (2005).
6Chabinyc, M. L. et al. Effects of the surface roughness of plastic-compatible inorganic dielectrics on polymeric thin film transistors. Applied Physics Letters 90, 233508, doi:10.1063/1.2746955 (2007).
7Lee, H. S. et al. Effect of the Phase States of Self-Assembled Monolayers on Pentacene Growth and Thin-Film Transistor Characteristics. Journal of the American Chemical Society 130, 10556-10564, doi:10.1021/ja800142t (2008).
8Jang, Y. et al. Effects of the permanent dipoles of self-assembled monolayer-treated insulator surfaces on the field-effect mobility of a pentacene thin-film transistor. Applied Physics Letters 90, 132104, doi:10.1063/1.2457776 (2007).
9Veres, J., Ogier, S. D., Leeming, S. W., Cupertino, D. C. & Mohialdin Khaffaf, S. Low-k Insulators as the Choice of Dielectrics in Organic Field-Effect Transistors. Advanced Functional Materials 13, 199-204, doi:10.1002/adfm.200390030 (2003).
10Anslyn, E. V. & Dougherty, D. A. Modern Physical Organic Chemistry. (University Science Books, 2006).
11Chen, W., Huang, H., Thye, A. & Wee, S. Molecular orientation transition of organic thin films on graphite: the effect of intermolecular electrostatic and interfacial dispersion forces. Chemical communications, 4276-4278, doi:10.1039/b805788e (2008).
12Lukas, S., Witte, G. & Woll, C. Novel Mechanism for Molecular Self-Assembly on Metal Substrates: Unidirectional Rows of Pentacene on Cu(110) Produced by a Substrate-Mediated Repulsion. Physical Review Letters 88, doi:10.1103/PhysRevLett.88.028301 (2001).
13France, C. B., Schroeder, P. G., Forsythe, J. C. & Parkinson, B. A. Scanning tunneling microscopy study of the coverage-dependent structures of pentacene on Au(111). Langmuir 19, 1274-1281, doi:10.1021/la026221v (2003).
14Mao, H. Y. et al. Chemical vapor deposition graphene as structural template to control interfacial molecular orientation of chloroaluminium phthalocyanine. Applied Physics Letters 99, 093301-093303 (2011).
15Singha Roy, S., Bindl, D. J. & Arnold, M. S. Templating Highly Crystalline Organic Semiconductors Using Atomic Membranes of Graphene at the Anode/Organic Interface. The Journal of Physical Chemistry Letters 3, 873-878, doi:10.1021/jz201559g (2012).
16Novoselov, K. S. et al. Electric field effect in atomically thin carbon films. Science 306, 666-669, doi:10.1126/science.1102896 (2004).
17Xu, W., Mao, N. & Zhang, J. Graphene: a platform for surface-enhanced Raman spectroscopy. Small 9, 1206-1224, doi:10.1002/smll.201203097 (2013).
18Ling, X., Wu, J., Xu, W. & Zhang, J. Probing the effect of molecular orientation on the intensity of chemical enhancement using graphene-enhanced Raman spectroscopy. Small 8, 1365-1372, doi:10.1002/smll.201102223 (2012).
19Wikipedia contributors. Pi interaction, <http://en.wikipedia.org/w/index.php?title=Pi_interaction&oldid=559033024>
Ch3
1Chang, C. K. et al. Band Gap Engineering of Chemical Vapor Deposited Graphene by in Situ BN Doping. ACS Nano 7, 1333-1341, doi:10.1021/nn3049158 (2013).
2Wikipedia contributors. Cryopump, <http://en.wikipedia.org/w/index.php?title=Cryopump&oldid=542476880> (
3Chen, Y. H. et al. Vacuum-deposited small-molecule organic solar cells with high power conversion efficiencies by judicious molecular design and device optimization. Journal of the American Chemical Society 134, 13616-13623, doi:10.1021/ja301872s (2012).
4Wikipedia contributors. Crystal oscillator, <http://en.wikipedia.org/w/index.php?title=Crystal_oscillator&oldid=559381488> (
5Smith, W. E. & Dent, G. ( John Wiley & Sons, Ltd, 2005).
6Tanaka, M. & Young, R. J. Review Polarised Raman spectroscopy for the study of molecular orientation distributions in polymers. Journal of Materials Science 41, 963-991, doi:10.1007/s10853-006-6595-7 (2006).
7Paez-Sierra, B. A. Raman Spectroscopy of Metal/Oragnic/Inorganic Heterostructures and Pentacene-Based OFETs Doctoral dissertation thesis, Chemnitz University of Technology, (2007).
8Birkholz, M. Thin Film Analysis by X-Ray Scattering. (Wiley, 2006).
9Moram, M. A. & Vickers, M. E. X-ray diffraction of III-nitrides. Reports on Progress in Physics 72, 036502, doi:10.1088/0034-4885/72/3/036502 (2009).
10Yılmaz, F. (InTech, 2013).
11Jalili, N. & Laxminarayana, K. A review of atomic force microscopy imaging systems: application to molecular metrology and biological sciences. Mechatronics 14, 907-945, doi:10.1016/j.mechatronics.2004.04.005 (2004).
12Alessandrini, A. & Facci, P. AFM: a versatile tool in biophysics. Measurement Science and Technology 16, R65-R92, doi:10.1088/0957-0233/16/6/r01 (2005).
13Hsu, Y.-J. (ed Dept. of Materials Science and Engineering) (National Chiao Tung University).
14Żenkiewicz, M. Methods for the calculation of surface free energy of solids. Journal of Achievements in Materials and Manufacturing Engineering 24 (2007).
15Young, T. An Essay on the Cohesion of Fluids. Philosophical Transactions of the Royal Society of London 95, 65-87, doi:10.1098/rstl.1805.0005 (1805).
16Bangham, D. H. & Razouk, R. I. Adsorption and the wettability of solid surfaces. Transactions of the Faraday Society 33, 1459-1463, doi:10.1039/TF9373301459 (1937).
17Fowkes, F. M. ATTRACTIVE FORCES AT INTERFACES. Industrial and Engineering Chemistry 56, 40-&, doi:10.1021/ie50660a008 (1964).
18Wednt, D. K. O. R. C. Estimation of the Surface Free Energy of Polymers. Journal of Applied Polymer Science 13, 1741-1747 (1969).
19顧惕人, 朱步瑤, 李外郎,馬記銘,戴樂蓉,程虎民. 表面化學. (科學出版社, 1994).
20 (Keithley 4200-SCS).
Ch4
1 Dimitrakopoulos, C. D. & Malenfant, P. R. L. Organic Thin Film Transistors for Large Area Electronics. Advanced Materials 14, 99-117, doi:10.1002/1521-4095(20020116)14:2<99::AID-ADMA99>3.0.CO;2-9
(2002).
2 Cheng, H. L., Chou, W. Y., Kuo, C. W., Tang, F. C. & Wang, Y. W. Electric field-induced structural changes in pentacene-based organic thin-film transistors studied by in situ micro-Raman spectroscopy. Applied Physics Letters 88, 161918-161913 (2006).
3 Oehzelt, M., Resel, R., Suess, C., Friedlein, R. & Salaneck, W. R. Crystallographic and morphological characterization of thin pentacene films on polycrystalline copper surfaces. The Journal of Chemical Physics 124, 054711-054716 (2006).
4 Cheng, H. L., Mai, Y. S., Chou, W. Y., Chang, L. R. & Liang, X. W. Thickness-Dependent Structural Evolutions and Growth Models in Relation to Carrier Transport Properties in Polycrystalline Pentacene Thin Films. Advanced Functional Materials 17, 3639-3649, doi:10.1002/adfm.200700207 (2007).
5 Bouchoms, I. P. M., Schoonveld, W. A., Vrijmoeth, J. & Klapwijk, T. M. Morphology identification of the thin film phases of vacuum evaporated pentacene on SIO2 substrates. Synthetic Metals 104, 175-178, doi:http://dx.doi.org/10.1016/S0379-6779(99)00050-8 (1999).
6 Mattheus, C. C., de Wijs, G. A., de Groot, R. A. & Palstra, T. T. M. Modeling the Polymorphism of Pentacene. Journal of the American Chemical Society 125, 6323-6330, doi:10.1021/ja0211499 (2003).
7 Alexander, L. X-ray diffraction methods in polymer science. Journal of Materials Science 6, 93-93, doi:10.1007/BF00550300 (1971).
8 Ruiz, R. et al. Pentacene Thin Film Growth. Chemistry of Materials 16, 4497-4508, doi:10.1021/cm049563q (2004).
9 Drummy, L. F. & Martin, D. C. Thickness-Driven Orthorhombic to Triclinic Phase Transformation in Pentacene Thin Films. Advanced Materials 17, 903-907, doi:10.1002/adma.200400189 (2005).
10 Li, X. et al. Graphene films with large domain size by a two-step chemical vapor deposition process. Nano letters 10, 4328-4334, doi:10.1021/nl101629 (2010).
11 Ferrari, A. C. & Basko, D. M. Raman spectroscopy as a versatile tool for studying the properties of graphene. Nat. Nanotechnol. 8, 235-246, doi:10.1038/nnano.2013.46 (2013).
12 Sahoo, S., Palai, R. & Katiyar, R. S. Polarized Raman scattering in monolayer, bilayer, and suspended bilayer graphene. Journal of Applied Physics 110, 044320, doi:10.1063/1.3627154 (2011).
13 Salaneck, W. R., Seki, K., Kahn, A. & Pireaux, J. J. Conjugated Polymer And Molecular Interfaces: Science And Technology For Photonic And Optoelectronic Application. (Taylor & Francis, 2001).