Complementary circuits have a number of advantages over unipolar circuits, including lower power consumption and greater noise immunity. But unlike unipolar circuits, which only require field-effect transistors of one carrier type (i.e., either p-channel or n-channel transistors), complementary circuits require both p-channel and n-channel transistors. In organic electronics, this creates a large incentive for the development of n-channel organic thin-film transistors (TFTs) with performance and stability on par with the best p-channel organic TFTs. Historically, the most promising results in this direction were achieved using core-cyanated fluoroalkyl-perylene tetracarboxylic dimides (PTCDIs), developed by Antonio Facchetti et al. (Angew. Chem. Int. Ed., vol. 43, p. 6363, 2004), and using core-halogenated fluoroalkyl-naphthalene tetracarboxylic dimides (NTCDIs), developed by Frank Würthner et al. (Adv. Funct. Mater., vol. 20, p. 2148, 2010). Together with expert synthetic chemists at the University of Würzburg, at Heidelberg University, and at BASF we have been investigating the use of these well-established materials as well as of a wide variety of novel compounds, such as core-halogenated tetraazaperopyrenes (TAPPs) and tetraazapyrenes (TAPys), developed by Lutz Gade et al., for the realization of flexible, low-voltage n-channel organic TFTs and organic complementary circuits.

Core-Brominated Tetraazaperopyrenes as n-Channel Semiconductors for Organic Complementary Circuits on Flexible Substrates
S. Geib, U. Zschieschang, M. Gsänger, M. Stolte, F. Würthner, H. Wadepohl, H. Klauk, L. H. Gade
Advanced Functional Materials, vol. 23, no. 31, pp. 3866-3874, August 2013

Contact properties of high-mobility, air-stable, low-voltage organic n-channel thin-film transistors based on a naphthalene tetracarboxylic diimide
R. Rödel, F. Letzkus, T. Zaki, J. N. Burghartz, U. Kraft, U. Zschieschang, K. Kern, H. Klauk
Applied Physics Letters, vol. 102, no. 23, pp. 233303/1-5, June 2013

1,3,6,8-Tetraazapyrenes: Synthesis, Solid-State Structures, and Properties as Redox-Active Materials
S. Geib, S. C. Martens, U. Zschieschang, F. Lombeck, H. Wadepohl, H. Klauk, L. H. Gade
Journal of Organic Chemistry, vol. 77, no. 14, pp. 6107-6116, July 2012

Tetrachlorinated Tetraazaperopyrenes (TAPPs): Highly Fluorescent Dyes and Semiconductors for Air-Stable Organic n-Channel Transistors and Complementary Circuits
S. C. Martens, U. Zschieschang, H. Wadepohl, H. Klauk, L. H. Gade
Chemistry - A European Journal, vol. 18, no. 12, pp. 3498-3509, March 2012

Low-voltage organic n channel thin-film transistors based on a core-cyanated perylene tetracarboxylic diimide derivative
U. Zschieschang, K. Amsharov, R. T. Weitz, M. Jansen, H. Klauk
Synthetic Metals, vol. 159, no. 21-22, pp. 2362-2364, November 2009

The Importance of Grain Boundaries for the Time-Dependent Mobility Degradation in Organic Thin-Film Transistors
R. T. Weitz, K. Amsharov, U. Zschieschang, M. Burghard, M. Jansen, M. Kelsch, B. Rhamati, P. A. van Aken, K. Kern, H. Klauk
Chemistry of Materials, vol. 21, no. 20, pp. 4949-4954, October 2009

Organic n-Channel Transistors Based on Core-Cyanated Perylene Carboxylic Diimide Derivatives
R. T. Weitz, K. Amsharov, U. Zschieschang, E. Barrena Villas, D. K. Goswami, M. Burghard, H. Dosch, M. Jansen, K. Kern, H. Klauk
Journal of the American Chemical Society, vol. 130, no. 14, pp. 4637-4645, April 2008