Ester-Flanked π-Extended Quinolines for Solution-Processable Ambipolar Organic Field-Effect Transistors

A series of π-extended quinolines with D−π–A–D and D−π–A–A architectures were designed and synthesized via the Sonagashira cross-coupling reaction to serve as ambipolar organic semiconductors for use in C–FET. Ambipolar mobilities were observed for methoxy- and tert-butyl group-substituted compounds. Among the molecules studied, π-extended methyl 2-(4-methoxyphenyl)-6-((4-methoxyphenyl)ethynyl)quinoline-4-carboxylate with D−π–A–D architecture exhibited high ambipolar transistor characteristics with hole and electron mobilities of 0.10 and 0.05 cm2/V s, respectively. The good charge carrier mobilities are supported by an electron-donating methoxy group with high highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels, extensive π-conjugation, and better self-assembly. Organic field-effect transistor (OFET) devices were fabricated using the spin-coating technique with BGTC configuration. By employing the postannealing technique, self-assembled crystalline films were obtained as depicted by scanning electron microscopy (SEM). These compounds can find potential applications in organic light-emitting transistors, sensors, and logic circuits.