1. 1 Organic Semiconductor Gaojie Lu ECE423 Presentation 12-16-2006

2. 2 Outline For Organic Semiconductor Introduction to Organic Semiconductor Relation of Organic Semiconductors to Inorganic Characteristics of Organic Semiconductor Organic Semiconductor Devices Future Applications Summary

3. 3 Introduction to Organic Semiconductor  Organic Semiconductors are semiconductors which use organic molecules rather than silicon for their active material. This active material can be composed of a wide variety of molecules Low cost of the technology Compatibility with plastic substances Lower temperature manufacturing (60-120° C) Possible to achieve flexible structures Low voltages, comparable with the performance for solution monitoring and some innovative applications

4. 4 Relation of Organic Semiconductors to Inorganic Also studied for more than 50 years Huge variety of choices for organic molecules for use in semiconductors Charge transport significantly different Usually comprised of many individual molecules held together by Van der Waals forces Many different fabrication techniques on different substrates C60

5. 5 Generally operate under accumulation mode, not inversion mode Relation of Organic Semiconductors to Inorganic Cont.

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7. 7 Mobilities of organic semiconductors have improved by five orders of magnitude over the past 15 years. Large research efforts using materials such as these led to some of this increase.

8. 8 Organic Semiconductors Device-OLED An organic light-emitting diode (OLED) is a special type of light- emitting diode (LED) in which the emissive layer comprises a thin-film of certain organic compounds. The emissive electroluminescent layer can include a polymeric substance that allows the deposition of very suitable organic compounds For example, in rows and columns on a flat carrier by using a simple "printing" method to create a matrix of pixels which can emit different colored light.

9. 9 Organic Semiconductors Device-OTFT TFTs are transistors created using thin films, usually of silicon deposited on glass. The deposited silicon must be crystallized using laser pulses at high temperatures. For organics to compete with a-S:H, their mobility should be greater than 0.1 cm²/V s and their on/off current ratio of greater than 106 OTFTs active layers can be thermally evaporated and deposited at much lower temperatures (i.e. 60° C)

10. 10 Organic TFT Tightness Benefits  Does not require a glass substrate as amorphous silicon does  Low temperature manufacture  Could be made on a piece of plastic  Deposition techniques could reduce costs dramatically Challenges  Workarounds for complications with photoresists  Finding organic semiconductors with high enough mobilities & switching times

11. 11 Future Outlook OTFTs for active-matrix displays Flexible view screens (or anything…) New generations of smart cards Organic smart pixels with OLEDs Large-area display electronics Organic semiconductor advances in mobility, switching time, and manufacturing may lead to many possibilities

12. 12 References H. E. Katz, Z. Bao, and S. J. Gilat, J. Acc. Chem. Res., vol.34, pp.359, 2001. Nandita Madhavan, “Small-molecule organic semiconductors,” April 01, 2002. A. Dodabalapur, “The future of organic semiconductor devies,” Device Research Conference 2000, Conference Digest, pp. 11-14, June 2000. http://assets.cambridge.org/052182/3307/excerpt/0521823307_excerpt.pdf http://www.aist.go.jp/aist_e/latest_research/2004/20041118/20041118.html [11] C. D. Dimitrakopoulos and D. J. Mascaro, “Organic thin-film transistors: A review of recent advances,” IBM J. Res. & Dev. Vol. 45, No. 1, Jan. 2001. [12] C. Reese, M. Roberts, M. M. Ling and Z. Bao, “Organic thin film transistors,” materialstoday, pp.20-27, Sept. 2004. [13] Y. Inoue, et al., “Organic Thin-file transistors with high electron mobility based on perfluoropentacene,” Japan Society of Applied Physis, Vol. 44, No. 6A pp. 3663-3668, 2005 Gao Z Q, Lee C S, Bello I, Lee S T, Chen R M, Luh T Y, Shi J and Tang C W 1999 Appl. Phys. Lett. 74, 865 Kulkarni A P, Gifford A P, Tonzola C J and Jenekhea S A 2005 Appl. Phys. Lett. 86, 061106-1 Shi J M and Tang C W 2002 Appl. Phys. Lett. 80, 3201 Gebeyehu D, Walzer K, He G, Pfeiffer M, Leo K, Brandt J, Gerhard A, Stössel P and Vestweber H 2005 Synth. Met. 148, 205 Hosokawa C, Higashi H, Nakamura H and Kusumoto T 1995 Appl. Phys. Lett. 67, 3853 Liao C H, Lee M T, Tsai C H and Chen C H 2005 Appl. Phys. Lett. 86, 203507 Wu Y Z, Zheng X Y, Zhu W Q, Sun R G, Jiang X Y, Zhang Z L and Xu S H 2003 Appl. Phys. Lett. 83, 5077 Morin J F, Leclerc M, Adès D and Siove A 2005 Macromol. Rapid Commun. 26, 761 http://www.oea-osc.com/persp_overview.htm http://www.phys.unsw.edu.au/~arh/background/Organic%20Electronics/Organics.html http://pubs.acs.org/hotartcl/ci/00/apr/0650wallace.html http://www.drproctor.com/os/ www.st-andrews.ac.uk/~osc/org-semi.html A.Tsumura, H. Koezuka, T. Ando,Appl.Phys.Lett. 49 (1986) 1210 G. Horowitz, X. Peng, D. Fichou, F. Garnier. J.Appl.Phys. 67 (1989) 528 S. R. Forrest, Nature 428, 911 (2004). T. Tsujimura, SID 2003 Technical Digest Vol.XXXIV, N. Greenham and R. H. Friend, in Solid State Physics: Advances in Research and Applications, Vol. 49, H. Ehrenreich and F. Spaepen, Eds., Academic Press, San Diego, 1995, pp. 1–149. A. J. Lovinger and L. J. Rothberg, “Electrically Active Organic and Polymeric Materials for Thin-Film- Transistor-Applications,” J. Mater. Res. 11, 1581 (1996). N. Hirohata, T. Tada and S. Yagyu: Proc. Int. Display Workshop 2004(IDW’04), p. 355. Baude, P. F., et al., Appl. Phys. Lett. (2003) 82 (22), 3964 Kelley, T. W., et al., Mater. Res. Soc. Symp. Proc. (2003) 771, 169 Sundar, V. C., et al., Science (2004) 303, 1644 Dimitrakopoulos, C. D., and Malenfant, P. R. L., Adv. Mater. (2002) 14 (2), 99 Kagan, C. R., Thin Film Transistors, Marcel Dekker Inc., New York, (2003) Zhang, J., et al., Appl. Phys. Lett. (2004) 84 (1), 142 Yuan, J., et al., Appl. Phys. Lett. (2003) 82 (22), 3967 Bao, Z., et al., Appl. Phys. Lett. (1996) 69 (20), 3066 Lin, Y.-Y., et al., IEEE Trans. Electron Dev. (1997) 44 (8), 1325 Katz, H. E., J. Mater. Chem. (1997) 7 (3), 369 Park, S. K., et al., IEEE Trans. Electron Dev. (2002) 49 (11), 200822. Malenfant, P. R. L., et al., Appl. Phys. Lett. (2002) 80

13. 13 Thank you!