Low-Temperature-Processible, Transparent, and Air-Operable n-Channel Fluorinated Phenylethylated Naphthalenetetracarboxylic Diimide Semiconductors Applied to Flexible Transistors

New N,N'-disubstituted-1,4,5,8-naphthalene tetracarboxylic acid diimides (NTCDI) with fluorinated phenylethyl groups were synthesized. In particular, N,N'-bis(2-(pentafluorophenyl)ethyl)-1,4,5,8-naphthalene tetracarboxylic acid diimide (5FPE-NTCDI) showed high electron mobility, more than 0.1 cm(2)/(V s) in air, even though the film was deposited at room temperature. The correlation of the crystallinity, morphology, and mobility with the substrate temperature during deposition (Tub) was studied using X-ray diffraction (XRD) and atomic force microscopy (AFM). The films of 5FPE-NTCDI exhibited a thin film phase, mixed phase, and crystal bulk phase as Tub was increased. The mixed phase on an octadecyltrimethoxysilane (OTS)-treated substrate also has high electron mobility due to well connected long fiber-shaped grains. The high mobility at low T-sub has enabled fabrication of flexible transistors on the clear plastic substrate poly(ethylene terephthalate) (PET). The highest mobility for a flexible, transparent transistor was 0.23 cm(2)/(V s), obtained with low hysteresis.