Crystal Engineering of Biphenylene-Containing Acenes for High-Mobility Organic Semiconductors

Herein we report
the synthesis, crystal structures, and semiconductor
properties of new derivatives of bisnaphtho­[2′,3′:3,4]­cyclobut­[1,2-b:1′,2′-i]­anthracene
(BNCBA). It is found that the π–π stacking of BNCBA
in single crystals can be largely modified by alkyl substituting groups
of different lengths. In particular, the tetrahexyl derivative exhibits
π–π stacking with an unusual zigzag arrangement.
The variation of molecular packing also leads to a change in charge
transport characteristics as found from the theoretical calculation
of mobility on the basis of single-crystal structures. All of these
BNCBA derivatives function as p-type semiconductors in solution-processed
thin film transistors, and the tetrahexyl derivative exhibits a field
effect mobility as high as 2.9 cm2/(V s).