Solubility-improved Organic Semiconductor, Thiophene/Phenylene Co-oligomer (TPCO)

Organic electronics are electronics using organic semiconductors. A large number of next-generation organic devices are well developed because they are alternatives to inorganic materials. Such organic materials are promising for an electronic paper and a flexible display because they are lightweight and flexible in the processing.

Hotta et al. developed thiophene/phenylene co-oligomers (TPCOs) with several types of a thiophene-phenylene combination.¹⁾ The TPCOs are important semiconductor materials for organic electronics. One TPCO material has excellent carrier mobility comparable with that of amorphous silicon, and many of them are thermally stable and heat-resistant.

The AC5-Hx (1) has an n-hexyl group on one side of the molecule, thus it is a monoalkylated TPCO. 1 can be dissolved in THF in the amount of 0.41 g/L, suggesting more than 10 times the solubility over that of the non-alkylated AC5. A field-effect transistor (FET) measurement of 1 fabricated by a vapor deposition gave carrier mobility of μ = 5.9 × 10⁻³ cm²/Vs (bottom-contact configuration) and μ = 2.4 × 10⁻² cm²/Vs (top-contact configuration). The resulting carrier mobility of 1 was higher than that of the non-alkylated AC5.²⁾