Synthesis and electron-transporting properties of phenazine bisimides

Abstract

The dual incorporation of imide substituents and imine-type nitrogen atoms into π-systems represents an emerging guideline for the design of robust and high-performance n-type semiconductors. Herein, we have adapted this strategy to a simple molecular motif: anthracene, and thus synthesized phenazine bisimides (PzBIs). PzBIs exhibit superior electron affinity compared to anthracene bisimide and phenazine due to the presence of two types of functional electron-withdrawing units. The existence of imine-type nitrogen atoms in PzBI leads to the formation of two-dimensionally extended brickwork arrangements while anthracene bisimide forms one-dimensionally slipped-stacked arrays. Consequently, the electron mobility of the vacuum-deposited film of N,N′-dicyclohexyl PzBI is ten times higher than that of the corresponding anthracene bisimide. Furthermore, the OFET device of N,N′-bisheptafluorobutyl PzBI exhibits good air persistency, and its intrinsic electron mobility has been estimated to be approximately 0.7 cm² V⁻¹ s⁻¹ by the time-resolved microwave conductivity measurement. The current study demonstrates that the dual incorporation strategy endows even a simple and small π-system with good performance as an n-type semiconductor.