臺灣博碩士論文加值系統

我們研究以熱蒸鍍法，在玻璃基板上成長並五苯(pentacene)和有機發光二極體薄膜(C47H32N2O2)的橢圓儀光譜性質。
　　首先，我們觀察到pentacene薄膜顯示一個1.87 eV的明顯吸收峰。我們認為這個吸收峰為最高分子佔據軌域到最低分子未佔據軌域的能隙。此外，其他光子能量大於2 eV的吸收峰屬於電子躍遷到較高軌域的貢獻。同樣的，我們也觀察到有機半導體薄膜能隙約為2.48 eV。
　　此外，我們也測量這兩個樣品的變溫(200 ~ 450 K)光譜。我們觀察到pentacene薄膜的戴維杜夫分裂(Davydov splitting)，隨著溫度由450 K降低至200 K時，分裂的情況會由0.08擴展至0.122 eV。我們認為這個現象與單位晶胞中分子和分子軌域重疊(overlap)的變化有關。另一個有機半導體薄膜也有類似的情況。

The pentacene and organic-light-emitting-device (OLED, C47H32N2O2) thin films were grown on glass substrate by thermal evaporation technique. The optical constants of these thin films are studied using variable spectroscopic ellipsometry.
Room-temperature ellipsometric spectra of the pentacene thin film exhibit a main absorption peak at about 1.87 eV, which can be assigned to the HOMO-LUMO gap of pentacene. Moreover, other high-frequency peaks above 2 eV are likely due to the transitions of an electron excited to higher orbital or localized excitations. On the other hand, the HOMO- LUMO transition energy of OLED thin film moves toward 2.48 eV, indicating its more insulating character.
Temperature-dependent ellipsometric spectra of both thin films were measured in the range from 200 K to 450 K. With decreasing temperature, the Davydov splitting of pentacene thin film increases from 0.08 eV at T = 450 K up to 0.122 eV at T = 200 K. This behavior is due to molecular reorientations that cause changes in mutual molecular overlap within the unit cell. A similar change of absorption bands is also observed for OLED thin film.

Table of Contents

Abstract …………………………………………………………… i
Acknowledgements…………………………………………………… iii
Table of Contents…………………………………………………… iv
List of Figures ……………………………………………………… vi
List of Tables ………………………………………………………… xi

Chapter 1 Introduction ……………………………………………… 1
Chapter 2 Review of pervious experimental work …………… 7
2-1 Pentacene …………………………………………………… 7
2-2 OLED ……………………………………………………… 9
Chapter 3 Experimental techniques …………………………………18
3-1 Spectroscopic ellipsometry ………………………………… 18
3-2 Sample preparation ………………………………………… 24
Chapter 4 Results and discussion …………………………………32
4-1 Room temperature spectra………………………………… 32
4-2 Temperature dependence …………………………………… 35
Chapter 5 Summary ………………………………………………… 52
Reference …………………………………………………………… 53

Reference
1. M. Pope, and C. E. Swenberg, Electronic Processes in Organic Crystals and Polymers, Oxford University Press, Oxford (1999).
2. F. De Angelis, S. Cipolloni, L. Mariucci, and G. Fortunato, Appl. Phys. Lett. 88, 193508 (2006).
3. 葉永輝，”主動式有機發光二極體顯示器(AMOLED)現況與發展趨勢”，電子月刊第十一卷第八期第１２４頁。
4. http://www.opto.com.tw/products/oled-divisionintro.asp?langtype=eng
5. Tsumura, H. Koczuka and T. Ando, Appl. Phys. Lett. 49, 1210 (1986).
6. F. De Angelis, S. Cipolloni, and G. Fortunato, Appl. Phys. Lett. 88, 193508 (2006).
7. C. D. Sheraw, L. Zhou, J. R. Huang, D. J. Gundlach, and T. N. Jackson, Appl. Phys. Lett. 80, 1088 (2002).
8. N. Karl, Synth. Met. 133, 649 (2003).
9. Yuning Li, Yiliang Wu, Ping Liu, Zorica Prostran, Sandra Gardner, and Beng S. Ong, Chem. Mater. 19, 418 (2007).
10. C. T. Chen, Yi Wei, J. S. Lin, W. S. Chao, Yu- Tai Tao, and C. H. Chien, J. Am. Chem. Soc. 128, 10992 (2006).
11. K. Kim, Y. K. Yoon, S. P. Park, S.S. Kim, S. Im, and J.H. Kim, Journal of Superconductivity: Incorporating Novel Magnetism, 15, 6 (2002).
12. S.S. Kim, S.P. Park, J.H. Kim, and S. Im, Thin Solid Films 420, 19 (2002).
13. R. B. Campbell, J, Monteath Robertson, and J. Trotter, Acta Cryst. 14, 705 (1961).
14. T. Minakata, I. Nagoya, and M. Ozaki, J. Appl. Phys. 69, 7354 (1991).
15. Christine C. Mattheus, Gilles A. de Wijs, Robert A. de Groot, and Thomas T. M. Palstra, J. Am. Chem. Soc. 125, 6323 (2003).
16. Chaeho Kim, Kyoungyoon Bang, Ilsin An, C. J. Kang, Y.S. Kim, and D. Jeon, Current Applied Physics 6, 925 (2006).
17. M. Pope and C. E. Swenberg, Electronic Processes in Organic crystals and Polymers, 2nd ed. (Oxford University Press, New York, 1999).
18. Oksana Ostroverkhova, Svitlana Shcherbyna, David G. Cooke, Ray F. Egerton, and Frank A. Hegmann, J. Appl. Phys. 98, 033701 (2005).
19. A. Brillante, R. G. Della Valle, L. Farina, A. Girlando, M. Masino, and E. Venuti, Chem. Phys. Lett. 375, 490 (2003).
20. Yuning Li, Yiliang Wu, Ping Liu, Zorica Prostran, Sandra Gardner, and Beng S. Ong, Chem. Mater. 19, 418 (2007).
21. A. R. Brown, A. Pomp, C. M. Hart, and D. M. Science 270, 972 (1995).
22. A. R. Brown, A. Pomp, D. B. M. Klassen, E. E. Havinga, and P. T. Hertig, J. Appl. Phys. 79, 2136 (1996).
23. P. T. Hertig and C. M. Hart, Adv. Mater. 11, 480 (1999).
24. A. Afzali and T. L. J. Dimitrakopoulos, J. Am. Chem. Soc. 124, 8812 (2002).
25. K. P. Weidkamp, A. Afzali, R. M. Tromp, and R. J. Hamers, J. Am. Chem. Soc. 126, 12740 (2004).
26. F. De Angelis, S. Cipolloni, L. Mariucci, and G. Fortunato, Appl. Phys. Lett. 88, 193508 (2006).
27. K. Mullen and U. Scherf, Organic Light-Emitting Devices. Synthesis, Properties and Applications; Wiley: Weinheim, Germany, (2006).
28. 黃毓中，私立逢甲大學電子工程研究所碩士論文，91年6月。
29. Guide to Using WVASE32, J. A. Woollam Co., Inc.
30. 葉佳元，國立成功大學光電研究所碩士論文，(2005)。
31. W. Y. Chou, Y. S. Mai, H. L. Cheng, C. Y. Yeh, C. W. Kuo, F. C. Tang, D. Y. Shu, T. R. Yew, and T. C. Wen, Organic Electronics 7, 445 (2006).
32. A. Zibold, H. L. Liu, S. W. Moore, J. M. Graybeal, and D. B. Tanner, Phys. Rev. B 53, 11734 (1996).
33. F. Wooten, Optical properties of solids, Academic, New York, (1972).
34. Daniel Faltermeier, Bruno Gompf, Martin Dressel, Ashutosh K. Tripathi, and Jens Pflaum, Phys. Rev. B 74, 125416 (2006).
35. T. Jentzsch, H. J. Juepner, K. W. Brzezinka, and A. Lau, Thin Solid Films 315, 273 (1998).
36. S. Guha, J. D. Rice, Y. T. Yau, C. M. Martin, M. Chandrasekhar, H. R. Chandrasekhar, R. Guentner, P. Scanduicci de Freitas, and U. Scherf, Phys. Rev. B 67, 125204 (2003).