Constructing Bilayer-type Layered Herringbone Packing in Dithieno[a,h]anthracenes for Solution-processable Organic Semiconductors

The bilayer-type layered herringbone (LHB) packing has enhanced layered crystallinity, which is favorable for achieving efficient carrier transport. By utilizing asymmetric phenyl-alkyl substitution, this study successfully established a bilayer-type LHB packing for angular dithieno[a,h]anthracene ( a ADT), which itself does not have a layered structure. Their packing motifs are highly associated with the alkyl chain length. Ph- a ADT-C10 and Ph- a ADT-C12 formed similar bilayer-type LHB packing motifs, while Ph- a ADT-C8 with short octyl chain exhibited a different arrangement where the π-cores and octyl chains are interdigitated with each other, revealing short alkyl chains impede the LHB packing. Furthermore, the packing structure clearly affected the film-forming ability: Ph- a ADT-C10 and Ph- a ADT-C12 produced relatively uniform crystalline thin films, while Ph- a ADT-C8 afforded only thick and discontinuous crystalline domains. Notably, characteristic p -channel transistor characteristics with high mobility up to 1.46 cm 2 /(V s) were found in Ph- a ADT-C12 . Our findings reveal that asymmetric phenyl-alkyl substitution can serve as an effective method that can be utilized on various π-cores for exploring their carrier-transport potential by constructing a bilayer-type LHB structure.