Comparative study of long alkyl chain substituted naphthalene diimide derivatives as n-type organic thin-film transistor materials

In this study, vacuum-evaporated thin films of several naphthalene tetracarboxylic acid diimide derivatives substituted at the N and N' positions with long normal alkyl chains of varying lengths (NTCDI-Cn) were evaluated as active materials for n-type organic thin-film transistors (TFTs). The electron mobility (μe) of the TFTs increased with increasing chain length from octyl (NTCDI-C8) to pentadecyl (NTCDI-C15); those of NTCDI-C15 and C18 TFTs were of 0.262 ± 0.016 and 0.222 ± 0.016 cm2 V−1 s−1, respectively. However, the threshold voltage of the TFTs increased with increasing chain length.