Easily Synthesized Naphthalene Tetracarboxylic Diimide Semiconductors with High Electron Mobility in Air

Abstract

New N,N′-substituted 1,4,5,8-naphthalene tetracarboxylic diimides (NTCDIs) were synthesized in one step reactions, resulting in excellent electron mobilities in air as measured in organic field effect transistors (OFETs). Two perfluoroalkyl-benzyl N,N′ substituents were used, differing in the length of the perfluoroalkyl moieties on the benzyl portion of the molecule. Single crystals of the short chain compound 2 were successfully grown by horizontal vapor deposition, and crystal structures were obtained and analyzed. Devices from both compounds were fabricated on untreated and silane treated Si/SiO2 substrates. The longer chain compound 1 gives the largest field effect mobility, reaching 0.57 cm2/(V s) in air. This is competitive with the best air stable n-channel materials to date. In contrast to previously studied high mobility materials, 1 achieved mobilities near 0.4 cm2/(V s) without the use of dielectric substrate treatments. Additionally, 1 displays exemplary ordering regardless of surface treatment, as determined from X-ray diffraction, while 2 displays significant improvement in mobility and film structure when deposited on surface treated substrates.