Naphthalenetetracarboxylic Diimide-Based n-Channel Transistor Semiconductors:  Structural Variation and Thiol-Enhanced Gold Contacts

The synthesis and field-effect transistor (FET) electron mobility of ten N-substituted naphthalene 1,4,5,8-tetracarboxylic diimide (NTCDI) derivatives deposited at ambient and elevated temperatures are reported. Mobilities >0.01 cm2/(V s) were measured in air for three NTCDIs with partially fluorinated substituents, and >0.001 cm2/(V s) for a hydroxy-terminated compound. Mobilities 0.001−0.1 cm2/(V s) were also found for three n-alkyl NTCDIs, but only under vacuum; FET operation with gold bottom contacts was enabled by specific thiol coatings of the contacts. The highest mobility in air, >0.1 cm2/(V s), was conferred by 4-trifluoromethylbenzyl substitution, while 1H,1H-perfluorooctyl substitution resulted in an on/off ratio in air >105. Solution electrochemistry and solid-state X-ray and electron diffraction were employed to partially explain the results, and applications of the materials to complementary circuits are considered.