本論文提出一種以第二次噴印改善第一次噴印OLED材料平整度不均問題的方法。此方法以可精確定位的噴印技術將所需材料填補於因咖啡環效應產生之第一次噴印材料凹口內，以期改善電流及發光之分布均勻性。
本研究以積分精算第一次噴印材料之凹口體積，並配合順序、方向、重疊比例及分割區域之優化，達成將此凹口體積縮減73%的成果。本研究除提出以凹口左右兩側為基準之乾膜平整度標準差作為改善之量化驗證外，亦證明以此第二次噴印方法所造成之整體穿透率下降及電阻率上升分別不超過1.5%及15%，暗示了不需以特殊設備、材料及製程步驟改變OLED畫素之親疏水性即可改善乾膜平整度。

This research proposed a method that compensates the recess of the first OLED layer resulted from wet process by a second inkjet printing. The inkjet printing filled the material to the recess resulted in the first layer because of the coffee ring effects with precise positioning, in order to improve the current distribution and light emitting uniformity.
This research obtained the recess of the first layer by integration and reduced 73% recess volume with sequence, direction, overlap ratio, and segment amount optimizations. This research not only provided a methodology that evaluates the dry-film uniformity by standard deviation between the two peaks of the recess quantitatively, but also proved that the transmittance and the resistivity resulted from this method reduced and increased less than 1.5% and 15%, respectively. These result implied that the dry-film uniformity can be improved without extra facilities, material, and processes for the hydrophilicity and hydrophobicity of OLED.

[1] M. Pope, H. P. Kallmann, P. Magnante, Electroluminescence in Organic Crystal, J. Chem. Phys, 38, 2042, (1963)
[2] C. W. Tang, S. A. VanSlyke, Organic electroluminescent diodes, Applied Physics Letters 51, 913-915, (1987)
[3] J. H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks,K. Mackay, R. H. Friend, P. L. Burns, A. B. Holmes, Light-emitting diodes based on conjugated polymers,Nature,347 ,539, (1990)
[4] C. Adachi, S. Tokito, T. Tsutsui, S. Saito, Organic Electroluminescent Device with a Three-Layer Structure, jpn. J. Appl. phys. 27,713, (1988)
[5] C. Adachi, T. Tsutsui, S. Saito, Organic electroluminescent device having a hole conductor as an emitting layer, Appl. Phys. Lett. , 55, 1489, (1989)
[6] M. A. Baldo, D. F. O’Brien, M. E. Thompson, S. R. Forrest, Excitonic singlet-triplet ratio in a semiconducting organic thin film, Phys. Rev. B 60, 14422, (1999)
[7] M. A. Baldo, M. E. Thompson, S. R. Forrest, High-efficiency fluorescent organic light-emitting devices using a phosphorescent sensitizer, Nature 403, 750-753, (2000)
[8] K. K. B. Hon, L. Li, I. M. Hutchings, Direct writing technology-Advances and developments, CRIP Annals – Manufacturing Technology 57, 601-620, (2008)
[9] C. Zhong, C. Duan, F. Huang, H. Wu, Y. Cao, Material and devices toward fully solution processable organic light-emitting diodes, Chem. Mater. 23, 326, (2011)
[10] L. Duan, L. Hou, T.W. Lee, J. Qiao, D. Zhang, G. Dong, L. Wang, Y. Qiu, Solution processable small molecules for organic light-emitting diodes, J. Mater. Chem. 20, 6392, (2010)
[11] Y. F. Chang, Y. C. Chiu, H. C. Yeh, H. W. Chen, H. F. Meng, H. W. Lin, H. L. Huang, T. C. Chao, M. R. Tseng, H. W. Zan, S. F Horng, Unmodified small-molecule organic light-emitting diodes by blade coating, Org. Electron. 13, 2149, (2013)
[12] K. H. Shin, J. Cho, J. Jang, H. S. Jang, E. S. Park, K. Song, S. H. Kim, Polypyrrole top-contact electrodes patterned by inkjet printing assisted vapor deposition polymerization in flexible organic thin-film transistors, Organic Electronics, 13, 715–720, (2012)
[13] J. W. Song, J. Kim, Y. H. Yoon, B. S. Choi, J. H. Kim, C. S. Han, Inkjet printing of single-walled carbon nanotubes and electrical characterization of the line pattern, Nanotechnology 19,095702, (2008)
[14] Y. Tsuchiya, S. Haraguchi, M. Ogawa, T. Shiraki, H. Kakimoto, O. Gotou, T. Yamada, K. Okumoto, S. Nakatani, K. Sakanoue, S. Shinkai, Fine Wettability Control Created by a Photochemical Combination Method for Inkjet Printing on Self-Assembled Monolayers, Advanced MaterialsVolume 24, Issue 7, (2012)
[15] F. Torrisi, T. Hasan, W. Wu, Z. Sun, A. Lombardo, T. S. Kulmala, G. W. Hsieh, S. Jung, F. Bonaccorso, P. J. Paul, D. Chu, A. C. Ferrari, Inkjet-Printed Graphene Electronics, ACS Nano, 6, 2992, (2012)
[16] M. C. Gather, A. Köhnen, A. Falcou, H. Becker, K. Meerholz, Solution-Processed Full-Color Polymer Organic Light-Emitting Diode Display Fabricated by Direct Photolithography, Advanced Functional MaterialsVolume 17, Issue 2, (2007)
[17] C. H. Chang, H. C. Cheng, Y. J. Lu, K. C. Tien, H. W. Lin, C. L. Lin, C. J. Yang, C. C. Wu, Enhancing color gamut of white OLED displays by using microcavity green pixels, Organic Electronics 11, 247–254, (2010)
[18] T. Shimoda, K. Morii, S. Seki, H. Kiguchi, Inkjet Printing of Light-Emitting Polymer Displays, MRS BULLETIN, Volume 28, Issue 11, 821-827, (2003)
[19] R. Chesterfield, A. Johnson, C. Lang, M. Stainer, J. Ziebarth, Solution-Coating Technology for AMOLED Displays, Information Display frontline technology
[20] T. R. Hebner, C. C. Wu, D. Marcy, M. H. Lu, J. C. Sturm, Ink-jet printing of doped polymers for organic light emitting devices, APPLIED PHYSICS LETTERS VOLUME 72, NUMBER 5 2 , (1998)
[21] C. F. Madigan, T. R. Hebner, J. C. Sturm, Lateral Dye Distribution with Ink-Jet Dye Doping of Polymer Organic Light Emitting Diodes, Paper V.3.5, Proc. Symp. Mat. Res. Soc. vol.624
[22] Z. Ding, R. Xing , Q. Fu, D. Ma, Y. Han, Patterning of pinhole free small molecular organic light-emitting films by ink-jet printing, Organic Electronics 12, 703–709,(2011)
[23] H. Gorter, M.W.L. Slaats, M. Ren, W. Lu, C.J. Kuijpers, W.A. Groen, Toward inkjet printing of small molecule organic light emitting diodes, Thin Solid Films 532, 11–15, (2013)
[24] C. T. Chen, F. G. Tseng, C. C. Chieng , Evaporation evolution of volatile liquid droplets in nanoliter wells, Sensors and Actuators A 130–131, 12–19, (2006)
[25] C. T. Chen, C. C. Chieng, F. G. Tseng, Uniform Solute Deposition of Evaporable Droplet in Nanoliter Wells, J. MEMS, VOL. 16, NO. 5, (2007)
[26] F. Villani, P. Vacca, G. Nenna, O. Valentino, G. Burrasca, T. Fasolino, C. Minarini, D. Sala, Inkjet Printed Polymer Layer on Flexible Substrate for OLED Applications, J. Phys. Chem., 113, 13398–13402, (2009)
[27] F. Ely, C.O. Avellaneda, P. Paredez, V.C. Nogueira, T.E.A. Santos, V.P. Mammana, C. Molina, J. Brug, G. Gibson, L. Zhao, Patterning quality control of inkjet printed PEDOT:PSS films by wetting Properties, Synthetic Metals 161, 2129– 2134, (2011)
[28] M. J. J. Coenen, T. M. W. L. Slaats, T. M. Eggenhuisen, P. Groen, Inkjet printing the three organic functional layers of two-colored organic light emitting diodes, Thin Solid Films 583, (2015)
[29] J. Rhee, J. Wang, S. Cha, J. Chung, D. Lee, S. Hong, B. Choi, J. Goh, K. Jung, S. Kim, C. Ko, B. Koh, S. Sung, K. Park, N. Kim, K. Chung, H. Gregory, M. Bale, C. Creighton, B. Wild, A. Shawcross, L. Webb, M. Hatcher, R. Lees, M. Richardson, O. Bassett, S. Coats, J. Jongman, S. Goddard, P. Lyon, C. Murphy, P. Wallace, J. Carter, N. Athanassopoulou, A 14.1-in. Full-Color Polymer-LED Display with a-Si TFT Backplane by Ink-Jet Printing, SID Symposium Digest of Technical Papers, Volume 37, Issue 1, pages 895–897, (2006)
[30] J. X. Zhou, J. Y. H. Fuh, H. T. Loh, Y. S. Wong, Y. S. Ng, J. J. Gray, S. J. Chua, Characterization of drop-on-demand microdroplet printing, Int J Adv Manuf Technol, 48:243–250, (2010)
[31] P. Wilson, C. Lekakou, J. F. Watts, System Design and Process Optimization for the Inkjet Printing of PEDOT:Poly(styrenesulfonate), J. Micro Nano Manuf. 2, 011004-9, (2014)
[32] T. Young, An essay on the cohesion of fluids, Philosophical Transactions of the Royal Society of London, 95 : 65–87, (1805)
[33] R.D. Deegan, O. Bakajin, T. F. Dupont, G. Huber, S. R. Nagel, T. A. Witten, “Capillary flow as the cause of ring stains from dried liquid drops”, Nature 389, (1997).
[34] R.D. Deegan, O. Bakajin, T. F. Dupont, G. Huber, S. R. Nagel, T. A. Witten, “Contact line deposits in an evaporating drop,” Phys. Rev. E 62, (2000).
[35] X. Shen, C. M. Ho, T. S. Wong, “Minimal Size of Coffee Ring Structure,” J. Phys. Chem. B, 114, (2010)
[36] P. J. Yunker, T. Still, M. A. Lohr, A. G. Yodh, “Suppression of the coffee-ring effect by shape-dependent capillary interactions”, Nature 476, (2011)
[37] D. Soltman, V. Subramanian, “Inkjet-Printed Line Morphologies and Temperature Control of the Coffee Ring Effect,” Langmuir 24,(2008)
[38] R. Bhardwaj, X. Fang, P. Somasundaran, D. Attinger, Self-Assembly of Colloidal Particles from Evaporating Droplets: Role of DLVO Interactions and Proposition of a Phase Diagram, Langmuir 26, (2010)
[39] J. Yang, J. Shen, Doping effects in organic electroluminescent devices, J. Appl. Phys. 84, 2105, (1998)
[40] Z. Liu, J. Pinto, J. Soares, E. Pereira, Efficient multilayer organic light emitting diode, synth. Metals, 122, 177, (2010)
[41] Y. Sato, S. Ichinosawa, H. Kanai, Operation characteristics and degradation of organic electroluminescent devices, IEEE Journal of Selected Topics in Quantum Electronics, 4, 40, (1998)
[42] K. A. Higginson, X. Zhang, F. Papadimitrakopoulos, Thermal and Morphological Effects on the Hydrolytic Stability of Aluminum Tris(8-hydroxyquinoline) (Alq3), Chem. Mater. 10, 1017, (1998)
[43] S. A. Van Slyke, C. H. Chen, C. W. Tang, Organic electroluminescent devices with improved stability, Appl. Phys. Lett. 69, 2160, (1996)
[44] P. Wilson, C. Lekakou, J. F. Watts, A Comparative Assessment of Surface Microstructure and Electrical Conductivity Dependence on Co-Solvent Addition in Spin Coated and Inkjet Printed Poly(3,4-Ethylenedioxythiophene):-Polystyrene Sulphonate (PEDOT:PSS), Org. Electron., 13(3), pp. 409–418, (2012)
[45] Nuno Reis, Chris Ainsley, Brain Derby, Ink-jet delivery of particle suspensions by piezoelectric droplet ejectors, Journal of Applied Physics 97 (2005) 094903-6
[46] H. Mu, W. Li, R. Jones, A. Steckl, D. Klotzkin, A comparative study of electrode effects on the electrical and luminescent characteristics of Alq3/TPD OLED: Improvements due to conductive polymer (PEDOT) anode, Journal of Luminescence 126, 225–229, (2007)
[47] C. Chen, C. Chuang, Microdroplets of red photoresist inkjet printed onto commercial black matrix glasses, Micro & Nano Letters, Vol. 7, Iss. 8, pp. 733–735, (2012)