本論文主要是利用一般有機發光二極體的元件架構，研究多層波導結構下有機材料的ASE現象。主要的方法是在ITO透明導電電極與有機發光層(BSB-Cz)中間插入空間層，來解決ITO電極所產生的光學損耗。實驗發現插入較BSB-Cz折射率低的有機高分子電洞傳輸層PVK並優化其厚度，可將ASE的閥值能量降到與直接鍍製BSB-Cz於玻璃基板上一樣的等級，約0.78 uJ/pulse。主要原因為PVK插入後可以改善波導模態的光場分布，減少在ITO電極的光學損耗。然而，插入高折射率的電子傳輸層TiO2則無法看到明顯的ASE現象。原因可能為TiO2折射率過高，光子容易被侷限在TiO2這層裡面，減少了光子在有機發光層裡的光放大機制。最後也模擬了一維DFB共振腔結構，找出適當的週期使共振波長吻合發光材料增益最大的波長位置，並且能運用在有電極的多層波導結構。此研究可有助於之後對電激發有機雷射的開發。

In this paper, we study ASE phenomenon of organic materials in a multilayer waveguide structure based on the general OLED device configuration. The method is to insert a spacer between the transparent electrode (ITO) and the organic emitting layer (BSB-Cz) to reduce the optical losses introduced by the ITO electrode. In the experiments, we observe that by inserting an organic polymer hole transport layer (PVK) with the refractive index lower than BSB-Cz and the thickness optimized, the ASE threshold energy can be reduced down to about 0.78 uJ/pulse, similar to as when BSB-Cz is directly deposited on the glass substrate. The main reason is that insertion of PVK can restore the waveguide mode profile and reduce the optical losses in ITO layer. However, we didn’t observe the ASE obviously when inserting the electron transport layer (TiO2) with a higher refractive index than BSB-Cz. The reason is that the high refractive index of TiO2 results in the photons essentially confined in the TiO2 layer, and hence decreasing the photon light amplification mechanism in the organic emitting layer. Finally, we simulate one dimension DFB resonator, to find out the suitable period such that the resonant wavelength can match the peak gain wavelength of organic materials. This study can be applied to multilayer waveguide structure, and the future development of electrically pumped organic lasers.

[1] B.A. Bolto, R. McNeill and D.E. Weiss,“Electronic Conduction in Polymers. III. Electronic Properties of Polypyrrole,”Australian Journal of Chemistry 16(6) 1090 – 1103 (1963)
[2] C. K. Chiang, C. B. Fincher, Jr., Y. W. Park, and A. J. Heeger,“Electrical Conductivity in Doped Polyacetylene,”Phys. Rev. Lett. 39(17),1098-1101 (1977)
[3] C. W. Tang and S. A. VanSlyke,“Organic electroluminescent diodes,”Appl. Phys. Lett. 51,913 (1987)
[4] J. H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks, K. Mackay, R. H. Friend, P. L. Burns and A. B. Holmes,“Light-emitting diodes based on conjugated polymers,”Nature 347, 539 - 541 (1990)
[5] A. Tsumura, H. Koezuka, and T. Ando,“Macromolecular electronic device: Field‐effect transistor with a polythiophene thin film,”Appl. Phys. Lett. 49, 1210 (1986)
[6] J. Zaumseil and H. Sirringhaus,“Electron and Ambipolar Transport in Organic Field-Effect Transistors,”Chem. Rev. 107(4), 1296-1323 (2007)
[7] J. Xue, S. Uchida, B. P. Rand, and S. R. Forrest,“4.2% efficient organic photovoltaic cells with low series resistances,”Appl. Phys. Lett. 84, 3013-3015 (2004)
[8] J. Y. Kim, K. Lee, N. E. Coates, D. Moses, T.-Q. Nguyen, M.Dante, and A. J. Heeger,“Efficient Tandem Polymer Solar Cells Fabricated by All-Solution Processing,”Science, 317, 5835, 222-225 (2007)
[9] F. Hide, M. A. Diaz-Garcia, B. J. Schwartz, M. R. Andersson, Q. Pei, and A. J. Heeger,“Semiconducting Polymers: A New Class of Solid- State Laser Materials,”Science, 273, 5283, 1833-1836 (1996)
[10] N. Tessler, G. J. Denton, and R. H. Friend, “Lasing from conjugated-polymer microcavities,”Nature 382, 6593, 695-697 (1996)
[11] D. Yokoyama, M. Moriwake, and C. Adachi,“ Spectrally narrow emissions at cutoff wavelength from edges of optically and electrically pumped anisotropic organic films,”J. Appl. Phys. 103, 123104 (2008)
[12] P. Andrew, G. A. Turnbull, Ifor D. W. Samuel, and W. L. Barnes,“Photonic band structure and emission characteristics of a metal-backed polymeric distributed feedback laser,”Appl. Phys. Lett. 81, 954 (2002)
[13] P. Görrn, T. Rabe, T. Riedl, and W. Kowalsky,“Loss reduction in fully contacted organic laser waveguides using TE2 modes,”Appl. Phys. Lett. 91, 041113 (2007)
[14] B. H. Wallikewitz, M. de la Rosa, J. H.-W. M. Kremer, D. Hertel, and K. Meerholz,“A Lasing Organic Light-Emitting Diode,”Adv. Mater. 22(4), 531-534 (2010)
[15] M. A. Baldo, R. J. Holmes, and S. R. Forrest,“Prospects for electrically pumped organic lasers,”Phys. Rev. B 66, 035321 (2002)
[16] M. C. Gwinner, S. Khodabakhsh, M. H. Song, H. Schweizer, H. Giessen, and H. Sirringhaus,“Integration of a Rib Waveguide Distributed Feedback Structure into a Light-Emitting Polymer Field-Effect Transistor,”Adv. Funct. Mater. 19(9), 1360-1370 (2009)
[17] N. C. Giebink, and S. R. Forrest,“Temporal response of optically pumped organic semiconductor lasers and its implication for reaching threshold under electrical excitation,”Phys. Rev. B 79, 073302 (2009)
[18] H. Wang, F. Li, I. Ravia, B. Gao, Y. Li, V. Medvedev, H. Sun, N. Tessler, and Y. Ma1,“Cyano-Substituted Oligo(p-phenylene vinylene) Single Crystals: A Promising Laser Material,”Adv. Funct. Mater. 21(19), 3770-3777 (2011)
[19] M. Polo, A. Camposeo, S. Tavazzi, L. Raimondo, P.Spearman, A. Papagni, R. Cingolani, and D. Pisignano,“Amplified spontaneous emission in quaterthiophene single crystals,”Appl. Phys. Lett. 92, 083311 (2008)
[20] A. L. Briseno, S. C. B. Mannsfeld1, M. M. Ling, S. Liu, R. J. Tseng, C. Reese, M. E. Roberts, Y. Yang, F. Wudl and Z. Bao,“Patterning organic single-crystal transistor arrays,”Nature 444, 913 (2006)
[21] H. Yanagi, T. Morikawa, and S. Hotta,“Electroluminescence from low-dimensionally confined crystals of thiophene/p-phenylene co-oligomers,”Appl. Phys. Lett. 81, 1512 (2002)
[22] R. J. Tseng, R. Chan, V. C. Tung, and Y. Yang,“Anisotropy in Organic Single-Crystal Photovoltaic Characteristics,”Adv. Mater. 20(3), 435-438 (2008)
[23] M. Ichikawa, R. Hibino, M. Inoue, T. Haritani, S. Hotta, T. Koyama, and Y. Taniguchi,“Improved Crystal-Growth and Emission Gain-Narrowing of Thiophene/Phenylene Co-Oligomers”Adv. Mater. 15(3), 213-217 (2003)
[24] H. R.-Haghighi, S. Forget, S. Chénais, A. Siove, M.-C. Castex, and E. Ishow,“Laser operation in nondoped thin films made of a small- molecule organic red-emitter,”Appl. Phys. Lett. 95, 033305 (2009)
[25] S. Chénais, and S. Forget,“Recent advances in solid-state organic lasers,” Polymer International 61(3), 390-406 (2012)
[26] V. G. Kozlov, V. Bulovic, P. E. Burrows, M. Baldo, and V. B. Khalfin,“Study of lasing action based on Förster energy transfer in optically pumped organic semiconductor thin films,”J. Appl. Phys. 84, 4096 (1998);
[27] D. Schneider, T. Rabe, T. Riedl, T. Dobbertin, and M. Kröger,“Organic solid-state lasers based on sexiphenyl as active chromophore,”J. Appl. Phys. 98, 043104 (2005)
[28] M. Zavelani-Rossi, G. Lanzani, M. Anni, G. Gigli, R. Cingolani, G. Barbarella, and L. Favaretto,“Organic laser based on thiophene derivatives,”Synthetic Metals 139 ,901–903 (2003)
[29] H. Nakanotani, S. Akiyama, D. Ohnishi, M. Moriwake, M.Yahiro, T. Yoshihara, S.Tobita, and C. Adachi,“Extremely Low-Threshold Amplified Spontaneous Emission of 9,9′-Spirobifluorene Derivatives and Electroluminescence from Field-Effect Transistor Structure,”Adv. Funct. Mater. 17, 2328–2335 (2007)
[30] M. Gaal, C. Gadermaier, H. Plank, E. Moderegger, A. Pogantsch, G. Leising, and E.J.W. List,“Imprinted Conjugated Polymer Laser,”Adv. Mater. 15(14), 1165-1167 (2003)
[31] G. J. Denton, N.Tessler, M. A. Stevens, and R. H. Friend,“Spectral Narrowing in Optically Pumped Poly(p-phenylenevinylene) Films”Adv. Mater. 9(7), 547-551 (1997)
[32] C. Kallinger, M. Hilmer, A. Haugeneder, M. Perner, W. Spirkl, U. Lemmer, J. Feldmann, U. Scherf, K. Müllen, A. Gombert, and V. Wittwer,“A Flexible Conjugated Polymer Laser,”Adv. Mater. 10(12), 920-923 (1998)
[33] C. Bauer, H. Giessen, B. Schnabel, E.-B. Kley, C. Schmitt, U. Scherf, and R. F. Mahrt,“A Surface-Emitting Circular Grating Polymer Laser,”Adv. Mater. 13(15), 1161-1164 (2001)
[34] R. Xia, G. Heliotis, and D. D. C. Bradley,“Fluorene-based polymer gain media for solid-state laser emission across the full visible spectrum,”Appl. Phys. Lett. 82, 3599 (2003)
[35] G.Heliotis, D. D. C. Bradley, G. A. Turnbull, and Ifor D. W. Samuel,“Light amplification and gain in polyfluorene waveguides,”Appl. Phys. Lett. 81, 415 (2002)
[36] O. Inganäs, T. Granlund, M. Theander, M. Berggren, M.R. Andersson, A. Ruseekas, and V. Sundström,“Optical emission from confined poly(thiophene) chains,” Optical Materials, 9, 104-108 (1998)
[37] I. D. W. Samuel, and G. A. Turnbull,“Organic Semiconductor Lasers,”Chem. Rev. 107, 1272-1295 (2007)
[38] Richard S. Quimby, “Photonics and Lasers An Introduction”John Wiley and Sons, Inc. (2006)
[39] R. Xia, M. C.-Quiles, G. Heliotis, P.l Stavrinou, K. S. Whitehead, D. D.C. Bradley,“Significant improvements in the optical gain properties of oriented liquid crystalline conjugated polymer films,”Synthetic Metals 155, 274–278 (2005)
[40] M. D. McGehee, R. Gupta, S. Veenstra, E. K. Miller, M. A. Díaz-García, and A. J. Heeger,“Amplified spontaneous emission from photopumped films of a conjugated polymer,” Phys. Rev. B 58, 7035–7039 (1998)
[41] V. G. Kozlov, V. Bulovic´ , P. E. Burrows and S. R. Forrest,“Laser action in organic semiconductorwaveguideand double-heterostructure devices,”Nature 389, 362 (1997)
[42] H. Kogelnik and C. V. Shank,“Coupled Wave Theory of Distributed Feedback Lasers,”J. Appl. Phys. 43, 2327 (1972)
[43] T. Riedl, T. Rabe, H.-H. Johannes, W. Kowalsky, and J. Wang,“Tunable organic thin-film laser pumped by an inorganic violet diode laser,”Appl. Phys. Lett. 88, 241116 (2006)
[44] C. Karnutsch, C. Gýrtner, V. Haug, U. Lemmer, T. Farrell, B. S. Nehls, U. Scherf, J. Wang, T. Weimann, G. Heliotis, C. Pflumm, J. C. deMello, and D. D. C. Bradley,“Low threshold blue conjugated polymer lasers with first- and second-order distributed feedback,”Appl. Phys. Lett. 89, 201108 (2006)
[45] D. Schneider, T. Rabe, T. Riedl, T. Dobbertin, and O. Werner,“Deep blue widely tunable organic solid-state laser based on a spirobifluorene derivative,”Appl. Phys. Lett. 84, 4693 (2004)
[46] A. E. Vasdekis, S. A. Moore, A. Ruseckas, T. F. Krauss, and I. D. Samuel,“Silicon based organic semiconductor laser,”Appl. Phys. Lett. 91, 051124 (2007)
[47] V. Bulovic´ , V. G. Kozlov, V. B. Khalfin, and S. R. Forrest,“Transform-Limited, Narrow-Linewidth Lasing Action in Organic Semiconductor Microcavities,”Science 279, 553 (1998)
[48] Eugene Hecht,“Optics,”Addison-Wesley, 4th ed. (2002)
[49] C. R. Pollock, and M. Lipson,“Integrated Photonics,”Kluwer Academic Publishers (2003)
[50] 盧廷昌、王興宗,“半導體雷射技術”, 五南出版社 (2010)
[51] C. Walters, A. Keeney, C. T. Wigal, C. R. Johnston, and R. D. Cornelius,“The Spectrophotometric Analysis and Modeling of Sunscreens,”Journal of Chemical Education 74(1), 99-101 (1997)
[52] D, Yokoyama,“Molecular orientation in small-molecule organic light-emitting diodes,” J. Mater. Chem. 21, 19187 (2011)
[53] D. Yokoyama, A. Sakaguchi, M. Suzuki, and C. Adachi,“Horizontal molecular orientation in vacuum-deposited organic amorphous films of hole and electron transport materials,”Appl. Phys. Lett. 93, 173302 (2008)
[54] J. M. Winfield, C. L. Donley, and Ji-Seon. Kim,“Anisotropic optical constants of electroluminescent conjugated polymer thin films determined by variable-angle spectroscopic ellipsometry,” J. Appl. Phys. 102, 063505 (2007)
[55] H. Fujiwara,“Spectroscopic Ellipsometry Principles and Applications,”John Wiley and Sons Ltd press (2006)
[56] T. Zhai , X. Zhang, Z. Pang, and F. Dou,“Direct Writing of Polymer Lasers Using Interference Ablation,”Adv. Mater. 23, 1860–1864 (2011)
[57] K. Forberich, A. Gombert, S. Pereira, J. Crewett and U. Lemmer,“Lasing mechanisms in organic photonic crystal lasers with two- dimensional distributed feedback,”J. Appl. Phys. 100, 023110 (2006)
[58] D. Yokoyama, A. Sakaguch, M. Suzuki, C. Adachi,“Horizontal orientation of linear-shaped organic molecules having bulky substituents in neat and doped vacuum-deposited amorphous films,”Organic Electronics 10, 127–137 (2009)
[59] D. Yokoyama and C. Adachi,“In situ real-time spectroscopic ellipsometry measurement for the investigation of molecular orientation in organic amorphous multilayer structures,”J. Appl. Phys. 107, 123512 (2010)
[60] M. H. Song, D. Kabra, B. Wenger, R. H. Friend, and H. J. Snaith,“Optically-Pumped Lasing in Hybrid Organic–Inorganic Light-Emitting Diodes,”Adv. Funct. Mater. 19, 2130–2136 (2009)
[61] D. R. Scifres, R. D. Burnham, and W. Streifer,“Highly collimated laser beams from electrically pumped SH GaAs/GaAlAs distributed− feedback lasers”Appl. Phys. Lett. 26, 48 (1975)
[62]R. G. Hunsperger,“Integrated Optics Theory and Technology ,”Springer, 5th ed. (2002)