Synthesis and Characterization of Novel p-Type Alkyl Bithiophene End-Capped Anthracene and Naphthalene Derivatives for Organic Thin-Film Transistors

Abstract

New semiconductors having naphthalene and anthracene cores with hexylated bithiophene side units, 2,6-bis(5'-hexylbithiophen-2'-yl)naphthalene (HBT-NA) and 2,6-bis(5'-hexylbithiophen-2'-yl)anthracene (HBT-AN), were synthesized. HBT-AN and HBT-NA were characterized using FT-IR, H-1-NMR, Mass spectrum and elemental analysis. HBT-AN and HBT-NA showed well ordered crystalline with high thermal stabilities as evidenced by 5% weight loss at 447 degrees C for HBT-AN and 434 degrees C for HBT-NA. The closed packed structures between adjacent molecules were observed by studying UV-visible and photoluminescence (PL) in solution and film. The HOMO energy levels of HBT-NA and HBT-AN were found to be 5.47 eV and 5.42 eV, respectively. HBT-NA exhibits hole mobility of 8.4 x 10(-2) cm(2)/Vs and on/off ratio of 5.6 x 10(5). HBT-AN shows 5.2 x 10(-2) cm(2)/Vs and on/off ratio of 1.0 x 10(5).