Towards the Bisbenzothienocarbazole Core: A Route of Sulfurated Carbazole Derivatives with Assorted Optoelectronic...

Ladder-type molecules, which possess an extended aromatic backbone, are particularly sought within the optoelectronic field. In view of the potential of the 14H-bis[1]benzothieno[3,2-b:2',3'-h]carbazole core as a p-type semiconductor, herein we studied a set of two derivatives featuring a different alkylation patterning. The followed synthetic route, involving various sulfurated carbazole-based molecules, also resulted in a source of fluorophores with different emitting behaviors. Surprisingly, the sulfoxide-containing fluorophores substantially increased their blue fluorescence with respect to the nearly non-emitting sulfur counterparts. On this basis, we could shed light on the relationship between their chemical structure and their emission as an approach for future applications. Considering the performance in organic thin-film transistors, both bisbenzothienocarbazole derivatives displayed p-type characteristics, with hole mobility values up to 1.1 × 10^-3 cm² V^-1 s^-1 and considerable air stability. Moreover, the role of the structural design has been correlated with the device performance by means of X-ray analysis and the elucidation of the corresponding single crystal structures.