Influence of solvent on the film morphology, crystallinity and electrical characteristics of triisopropylsilyl pentacene OTFTs

The thin-film morphology, degree of crystallinity, as well as the electrical properties of triisopropylsilyl (TIPS) pentacene organic thin-film transistors (OTFTs) were significantly influenced by the solvent used for spin-coating a TIPS pentacene layer. The TIPS pentacene films spin-coated from solvents having high boiling points (chlorobenzene and xylene) showed dendritelike morphology and a higher degree of crystallinity, while TIPS pentacene spin-coated from solvent having a low boiling point (chloroform) showed amorphous-like morphology and a lower degree of crystallinity. The field-effect mobility of OTFTs fabricated from chlorobenzene was 4× 10-2 cm2 V s, whereas mobility of 10-4 to 10-5 cm2 V s was achieved when using chloroform. This implies that the morphology, crystallinity, as well as the electrical properties of TIPS pentacene have a strong dependence on the solvent used for spin-coating.