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標題: | 以石墨烯和二氧化矽基板調控並五苯分子排列 Templating Molecular Orientation of Pentacene Thin Films on Graphene and SiO2 Substrates |
作者: | Chiung-Yi Chen 陳瓊怡 |
指導教授: | 陳永芳(Yang-Fang Chen) |
關鍵字: | 分子排列,並五苯,石墨烯,偏極化拉曼光譜, molecular orientation,pentacene,graphene,polarized Raman spectroscopy, |
出版年 : | 2013 |
學位: | 碩士 |
摘要: | 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. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/62401 |
全文授權: | 有償授權 |
顯示於系所單位: | 物理學系 |
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