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 pi-pi stacking of BNCBA in single crystals can be largely modified by alkyl substituting groups of different lengths. In particular, the tetrahexyl derivative exhibits pi-pi 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 cm(2)/(V s).