© 2019 The Chemical Society of Japan. Bis[1]benzothieno[5,4-d:5¤,4¤-d¤]benzo[1,2-b:4,5-b¤]dithiophene (BBTBDT-2) and its phenyl-substituted derivative were successfully synthesized and characterized. From DFT calculations, highest occupied molecular orbitals (HOMOs) of both compounds are well delocalized and large orbital coefficients exist on sulfur atoms. Single-crystal X-ray analysis revealed that BBTBDT-2 derivatives formed herringbone structures in the solid state. In particular, BBTBDT-2 formed a layer-by-layer structure with effective 2D charge-carrier transporting capability. The fabricated OFETs based on BBTBDT-2 gave mobility up to 0.49 cm2 V11 s11 in the vacuum-deposited thin films, which is the highest value among BBTBDT derivatives including our previously reported syn-counterparts. We have also clarified a detailed structureproperty relationship of sulfur positions and phenyl substituents as indicated by theoretical calculation, GIWAXS, and AFM analyses.