Synthesis and properties of thieno[3,2-b]thiophene derivatives for application of OFET active layer

Article abstract of DOI:10.1002/hc.21059

A series of thieno[3,2-b]thiophene derivatives having styryl groups were synthesized via short steps and characterized by UV-vis absorption spectra and cyclic voltammetry. Based on these results, we found that the introduction of long chain alkyl groups to the terminal styryl groups leads to narrower HOMO-LUMO gaps and higher HOMO energy levels than the unalkylated styryl substituted molecules. Organic field-effect transistor (OFET) devices using these derivatives as the active layer were fabricated by a vacuum deposition process. It was demonstrated that these devices showed a relatively high hole mobility up to 3.5 × 10^-2 cm²/Vs. These devices also showed a good stability, namely their mobilities did not decrease over 100 days in air. Therefore, these facts suggested that the introduction of long-chain alkylated styryl groups is an effective way to improve the hole mobilities in OFETs.