| AVS 63rd International Symposium & Exhibition | |
| Thin Film | Thursday Sessions |
| Session TF-ThP |
| Session: | Thin Films Poster Session |
| Presenter: | Michael Lee, Northern Arizona University |
| Authors: | M.V. Lee, Northern Arizona University R. Mendoza, Northern Arizona University R.T. Rodriguez, Northern Arizona University B.F. Kunzler, Northern Arizona University |
| Correspondent: | Click to Email |
Since bulk conductivity in organic crystals was discovered in the 1960s,[1] high mobilities for single-crystal organic semiconductors have been reported with 35 cm2 V-1 s-1 for pentacene,[2] and even 40 cm2 V-1 s-1 for rubrene.[3], [4] However, these large aromatic molecules are generally insoluble for solution-processing.[5] Optimized films have been prepared by solution-processing derivatized molecules, such as TIPS-pentacene. In TIPS-pentacene, the derivitized groups comprise over half of the mass. Optimized devices using modified pentacene can reach a carrier mobility of only 6 cm2 V-1 s-1.[6]
While much of the decrease is due to the polycrystalline nature of the films, the added functional groups also play a direct role. Their effect has been tested to some extent by synthesizing pentacene with removable functional groups. Preparing a film and removing of the functional groups gave nearly 50% increased mobility, or 8.8 cm2 V-1 s-1.[7]
We present our recent results on using an alternative strategy to directly solution-process unmodified pentacene and other large organic semiconductors into thin films that can be used for organic field-effect transistors and solar cells. This strategy can be extended to other large semiconductors without requiring organic synthesis of new molecules.
[1] H. Kallmann and M. Pope, “Bulk Conductivity in Organic Crystals,” Nature, vol. 186, no. 4718, pp. 31–33, Apr. 1960.
[2] O. D. Jurchescu, J. Baas, and T. T. M. Palstra, “Effect of impurities on the mobility of single crystal pentacene,” Appl. Phys. Lett., vol. 84, no. 16, pp. 3061–3063, Apr. 2004.
[3] V. Podzorov, S. E. Sysoev, E. Loginova, V. M. Pudalov, and M. E. Gershenson, “Single-crystal organic field effect transistors with the hole mobility ∼ 8cm2/V s,” Appl. Phys. Lett., vol. 83, no. 17, pp. 3504–3506, Oct. 2003.
[4] T. Hasegawa and J. Takeya, “Organic field-effect transistors using single crystals,” Sci. Technol. Adv. Mater., vol. 10, no. 2, p. 24314, Apr. 2009.
[5] R. S. Ruoff, D. S. Tse, R. Malhotra, and D. C. Lorents, “Solubility of fullerene (C60) in a variety of solvents,” J. Phys. Chem., vol. 97, no. 13, pp. 3379–3383, Apr. 1993.
[6] Y. Xu, M. Benwadih, R. Gwoziecki, R. Coppard, T. Minari, C. Liu, K. Tsukagoshi, J. Chroboczek, F. Balestra, and G. Ghibaudo, “Carrier mobility in organic field-effect transistors,” J. Appl. Phys., vol. 110, no. 10, pp. 104513-104513–9, Nov. 2011.
[7] K.-Y. Chen, H.-H. Hsieh, C.-C. Wu, J.-J. Hwang, and T. J. Chow, “A new type of soluble pentacene precursor for organic thin-film transistors,” Chem. Commun., no. 10, pp. 1065–1067, Feb. 2007.