Synthesis and electrical properties of novel oligomer semiconductors for organic field-effect transistors (OFETs): Asymmetrically end-capped acene-heteroacene conjugated oligomers

•Solubility of the small molecule semiconductors are enhanced by molecular design.•The phenylene and naphthalene are torsionally-combined into conjugated core.•Torsional structure increase solubility and thus increase thin film uniformity.•Therefore, long-range ordering and adequate mobility could be achieved.

Noble small molecules composed of an aromatic phenylene-trithiophene and naphthalene-trithiophene conjugated core were synthesized and examined for their property in p-type OFET devices. The phenylene and naphthalene moieties were combined with a trithiophene to introduce torsional structures into the conjugated core and improve the solubility compared with the solubility of the quaterthiophene core containing molecule. Although phenylene-trithiophene and naphthalene-trithiophene containing molecules showed lower mobilities (2.9 × 10−3 and 1.04 × 10−2 cm2/V, respectively) than quaterthiophene containing molecule (3.21 × 10−2 cm2/V), they showed more film uniformity caused by improved solubility. The thermal stability, photochemical properties, and morphological characteristics were investigated using TGA, DSC, cyclic voltammetry, and XRD techniques.

Graphical abstractThe good solubility is key factor for long range ordering in the OFETs. Therefore, we aim to enhance solubility by molecular design of small molecule semiconductor, and thus fabricate uniform thin film for p-type OFETs.Figure optionsDownload full-size imageDownload as PowerPoint slide