Synthesis and Evaluation of Charge Transport Property of Ethynylene‐Bridged Anthracene Oligomers

Abstract

A set of ethynylene‐bridged anthracene oligomers from monomer to tetramer is synthesized and characterized. The red‐shifts in the UV–vis absorption and fluorescence spectra indicate the π‐extension with elongation of the linear chain. Cyclic voltammetric measurements suggest that their highest occupied molecular orbitals are located lower than –5.0 eV, indicating high air stability. Single‐crystal X‐ray analysis of a trimer needle crystal indicates that anthracene units display a twisted arrangement, adopting a face‐to‐face packing structure. The dip‐coating method with a very slow pulling rate provides crystalline films of dimer and trimer. The top‐contact bottom‐gate organic field‐effect transistor devices reveal that trimer shows better charge transport property (8.0 × 10–3 cm2 V–1 s–1) than dimer (8.9 × 10–4 cm2 V–1 s–1). Furthermore, the single‐crystal field‐effect transistor of trimer shows mobility up to 0.14 cm2 V–1 s–1, which is higher than that of tetramer (3.3 × 10–2 cm2 V–1 s–1). This is likely due to the larger amount of defects in tetramer crystals that are caused by the free rotation of ethynylene units, while the trimer achieves a good balance between the effective π‐conjugation and defectless crystal formation.