The performance of organic thin-film transistors (TFTs) often degrades when the devices are exposed to air. This is generally ascribed to the generation of trap states as a result of the oxidation of the organic semiconductor.

One strategy to improve the stability of organic TFTs is the synthesis of conjugated semiconductors with a arger ionization potential. However, many organic semiconductors with large ionization potential show relatively small charge-carrier mobilities, due to the fact that these materials tend to show poor molecular ordering.

We have investigated the performance and stability of TFTs based on a series of novel organic semiconductors developed by Kazuo Takimiya et al., including dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) and one of its alkylated derivatives, C10-DNTT.

Owing to excellent molecular ordering in vacuum-deposited thin films, both DNTT and C10-DNTT provide relatively large field-effect mobilities, similar to or slightly better than pentacene. More importantly, DNTT and its derivatives have a larger ionization potential (~5.4 eV) than pentacene (~5.0 eV) and thus show significantly better long-term air stability.

Detailed analysis and contact properties of low-voltage organic thin-film transistors based on dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) and its didecyl and diphenyl derivatives
U. Kraft, K. Takimiya, M. J. Kang, R. Rödel, F. Letzkus, J. N. Burghartz, E. Weber, H. Klauk
Organic Electronics, vol. 35, pp. 33-40, May 2016

Low-voltage organic transistors based on tetraceno[2,3-b]thiophene: Contact resistance and air stability
U. Kraft, J. E. Anthony, E. Ripaud, M. A. Loth, E. Weber, H. Klauk
Chemistry of Materials, vol. 27, no. 3, pp. 998-1004, February 2015

Flexible Low-Voltage Organic Complementary Circuits: Finding the Optimum Combination of Semiconductors and Monolayer Gate Dielectrics
U. Kraft, M. Sejfic, M. J. Kang, K. Takimiya, T. Zaki, F. Letzkus, J. N. Burghartz, E. Weber, H. Klauk
Advanced Materials, vol. 27, no. 2, pp. 207-214, January 2015

High-mobility organic thin-film transistors based on a small-molecule semiconductor deposited in vacuum and by solution shearing
R. Hofmockel, U. Zschieschang, U. Kraft, R. Rödel, N. H. Hansen, M. Stolte, F. Würthner, K. Takimiya, K. Kern, J. Pflaum, H. Klauk
Organic Electronics, vol. 14, no. 12, pp. 3213-3221, December 2013

Flexible low-voltage organic thin-film transistors and circuits based on C10-DNTT
U. Zschieschang, M. J. Kang, K. Takimiya, T. Sekitani, T. Someya, T. W. Canzler, A. Werner, J. Blochwitz-Nimoth, H. Klauk
Journal of Materials Chemistry, vol. 22, no. 10, pp. 4273-4277, February 2012

Dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) thin-film transistors with improved performance and stability
U. Zschieschang, F. Ante, D. Kälblein, T. Yamamoto, K. Takimiya, H. Kuwabara, M. Ikeda, T. Sekitani, T. Someya, J. Blochwitz-Nimoth, H. Klauk
Organic Electronics, vol. 12, no. 8, pp. 1370-1375, June 2011

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