Air-stable organic semiconductors based on 6,6′-dithienylindigo and polymers thereof

Herein we report on the synthesis and properties of 6,6'-dithienylindigo (DTI), as well as its solubilized N,N'- di(tert-butoxy carbonyl) derivative (tBOC-DTI). tBOC-DTI can be electropolymerized and thermally interconverted into films of poly(DTI). Thin films of DTI afford quasi-reversible 2-electron reduction and oxidation electrochemistry, and demonstrate ambipolar charge transport in organic field-effect transistors with a hole mobility of up to 0.11 cm2 V-1 s-1 and an electron mobility of up to 0.08 cm2 V-1 s-1. Operation of the p-channel shows excellent air stability, with minimal degradation over a 60 day stressing study. Poly(DTI) can be reversibly oxidized and reduced over hundreds of cycles while remaining immobilized on the working electrode surface, and additionally shows a pronounced photoconductivity response in a diode device geometry. This work shows the potential of Extended indigo derivatives for organic electronic applications, demonstrating impressive stability under ambient conditions.