Thiophene-Grafted Cyclo-Carbazole Nanohoop as a Semiconducting Layer in OFETs

Nanohoops are a class of fascinating curved materials that have started to show their potential in organic electronics. Now, the next step consists of going deeper in their rational design in order to reach high performance materials. However, at this stage of their evolution in material science, the nanohoop properties and their device performance are far more complicated to forecast than those of their linear counterparts, and systematic studies dealing with the incorporation of functional units have to be carried out. Herein, we report a [4]cyclo-2,7-carbazole, possessing an electron-rich thiophene unit grafted on its nitrogen atoms. Incorporation in Organic Field-Effect Transistors (OFET) provides a saturated mobility of 3.2 × 10–5 cm2 V–1 s–1, among the highest reported to date for nanohoops. The other characteristics such as the low subthreshold swing (0.72 V/dec) or the high on/off values of the drain-source current (2.8 × 105) appear even to be the highest reported to date for a nanohoop.