During the last few years, the development of organic thin film transistors (OTFTs) has attracted much interest because organic molecules offer the opportunity of deposition over large surface areas and are compatible with flexible plastic substrates[1]. A number of organic compounds have been proposed for use in light-emitting diodes, field-effect transistors and photovoltaic cells. Pentacene has good semi-conducting properties but its practical use in organic thin film transistors (OTFTs) is limited due to its relative ease of oxidation and its low solubility. We have begun preparing a series of stabilized acenes that incorporate several different aryl substituents located at different positions along the acene backbone. In this presentation, we describe the formation, characterization and stability of the following series: 6,13-diphenylpentacene, 6,13-bis(2,6-dimethylphenyl)pentacene, 6,13-bis(2,6-diethylphenyl)pentacene, 5,7,12,14-tetraphenylpentacene, 5,7,12,14-tetrakis(2,6-dimethylphenyl)pentacene. All of these compounds show vastly improved solubility (processability) as compared to pentacene. Studies of the photo-oxidative stability of each compound demonstrate that substitution at the 6,13 positions of pentacene allows for greater stability than substitution at the 5,7,12,14 positions.

[1] Katz, H. E.; Bao, Z.; Gilat, S. L. Acc. Chem. Res. 2001, 34, 359-369.